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CONTENTS

CHAPTER TITLE PAGE

NO.

1. INTRODUCTION 1

1.1. Oral drug delivery system 1-8

1.2. Classification of sustained release polymeric drug

delivery systems

8-13

1.3. Fabrication of oral controlled release delivery

employs various methods

13-18

1.4. Matrix systems 19-21

1.5. Approaches for preparation of matrix dosage forms 21-23

1.6. Mechanism of drug release from matrix devices 23-29

2. NEED AND OBJECTIVES 30-31

3. PLAN OF WORK 31-33

4. LITERATURE REVIEW 34-41

4.1. Drug Profile 42-44

4.2. Excipients Profile 45-63

5. MATERIALS AND METHODS 64

5.1. Excipient Used 65

5.2. Equipments Used 66-74

5.3. Preformulation Study 74-74

5.4. Compression of Powder Blends into Tablets 74-79

5.5. Evaluation of Sustained Release Matrix Tablets 79

5.6. Stability Study 80


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6. RESULTS AND DISCUSSION 80

6.1. Preformulation Parameters 80-93

6.2. Evaluation of Sustained Release Matrix Tablets 93-117

6.3. Stability Study 117-

119

7. SUMMARY AND CONCLUSION 120

8. FUTURE PROSPECTS 121

9. BIBLIOGRAPHY 122-

127


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LIST OF FIGURES

FIGURE

NO.

CONTENTS PAGE

NO.

1.1 A hypothetical plasma concentrationtime profile fromconventional multiple and single doses of sustained and

controlled delivery formulations.

4

1.2 Schematic representation of diffusion controlled drug release

reservoir.

11

1.3 Schematic representation of diffusion controlled drug releasematrix system.

11

1.4 Drug delivery from environmentally pH sensitive releasesystems. 13

1.5 Hydrogel formation in Reservoir Systems. 14

1.6 Drug Release from a Matrix Tablets 15

1.7 Parameter definitions for swellable soluble matrix. 16

5.1 Schematic representation of compatibility studies 69

5.2 Steps in traditional Wet granulation techniques 71

6.1 max observed for Telmisartan in 0.1N HCl. 80

6.2 max observed for Telmisartan in 0.1N HCl. 81

6.3 Standard graph of Telmisartan 0.1N HCl. 83

6.4 Standard graph of Telmisartan in pH 6.8 Phosphate buffer. 84

6.5 FTIR Spectra of Telmisartan 86

6.6 FTIR Spectra of Telmisartan and HPMC K100M 86

6.7 FTIR Spectra of Telmisartan and ethyl cellulose 87

6.8 FTIR Spectra of Telmisartan and xanthan gum 876.9 DSC Thermal analysis of pure Telmisartan 89

6.10 DSC Thermal analysis of Telmisartan+ HPMC K100M 89

6.11 DSC Thermal analysis of Telmisartan + ethylcellulose 90

6.12 DSC Thermal analysis of Telmisartan + xanthan gum 90


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6.13 Drug release profile of formulation F1 96









6.22 Drug release profile of formulations containing HPMC K100Mpolymer

105

6.23 Drug release profile of formulations containing Ethylcellulosepolymer

105

6.24 Drug release profile of formulations containing Xanthan gumpolymer

106

6.25 Drug release profile of all nine formulations (F1 to F9) 107

6.26 Best fit model (Peppas) of formulation F1 111

6.27 Best fit model (Zero-order) of formulation F2 111



6.30 Best fit model (Peppas) of formulation F5 113





6.35 Comparisons of hardness for formulation F3 with initial anddifferent periods of stability

118

6.36 Comparisons of drug content for formulation F3 with initial anddifferent periods of stability

118

6.37 Comparisons of drug release profile for formulation F3 withinitial and different periods of stability

119


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LIST OF TABLES

TABLE

NO.

CONTENTS PAGE

NO.

1.1 Drug properties suitable for sustained release 6-8

1.2 Characteristics of major classes of sustained release drug delivery system 17-19

1.3 The characteristics of various types of matrices 19-21

1.4 Methods for preparation of matrices. 21-23

5.1 List of excipients with source 64

5.2 List of equipments with model/make 65

5.3 Composition of Telmisartan SR Matrix tablet 70

5.4Standard values of Carrs index 73

5.5 Standard values of angle of repose () 74

5.6 Specifications of % Weight Variation Allowed in Tablets as per Indian

Pharmacopoeia

76

6.1 The solubility of Telmisartan in various solvents 80

6.2 Data of concentration and absorbance for in Telmisartan 0.1N HCl 82

6.3 Data of concentration and absorbance for Telmisartan in pH 6.8

Phosphate buffer.

83

6.4 Data for Calibration Curve Parameters 84


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6.5 Percentage purity of pure drug 85

6.6 Data for characteristic frequencies in FTIR spectrum of

Telmisartan

87

6.7 Data for DSC thermogram parameters 91

6.8 Flow properties of powder 92

6.9 Physico-Chemical Characterization of Telmisartan SR Matrix

Tablets

94

6.10 Dissolution data of formulation F1 95



6.13 Dissolution data of formulation F4 98-99

6.14 Dissolution data of formulation F5 99-100

6.15 Dissolution data of formulation F6 100-

101


102


103


104

6.19 Different Kinetic models for Telmisartan SR Matrix Tablets (F1 to F9) 109-110

6.20 Stability studies of optimized formulation of Telmisartan SR tablet

(F3)

117


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LIST OF ABBREVIATIONS USED

BP - British Pharmacopeia

CDDS - Controlled drug delivery system

CDR - Cumulative drug release

CR - Controlled release

DE - Dissolution Efficiency

DSC

EC

- Differential Scanning Colorimetry

- Ethyl Cellulose

F - Formulation

FTIR - Fourier Transform Infra-red

GIT - Gastrointestinal tract

g - Gram

HPMC - HydroxyPropyl MethylCellulose

HCl - Hydrochloric acid

HBS - Hydro dynamically balanced system

M - Molarity

Mg - Miligram


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MRT - Mean residence time

MMC - migrating myoelectric complex

MCC - Microcrystalline cellulose

Mp - Melting point

MDT - Mean Dissolution Time

m -

ml -

Slope, Units of response

Milli litre

N - Normality

pH - Negative Logaritham of hydrogen ion

PVP - Polyvinyl pyrolidone

ppm - parts per million

RH - Relative humidity

rpm - Revolutions per minute

S.D.

S.R

SRDDS

- Standard deviation

- Sustained Release

- Sustained Release Drug Delivery System

t1/2 - Biological half-life

UV-VIS - Ultraviolet-Visible

USP - United State Pharmacopoeia

max - Absorption maximum

% - Percentage

g - Microgram

C - Degree Celsius


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INTRODUCTION

Department of Industrial Pharmacy, NIPS Page 1

1.INTRODUCTION

ORAL DRUG DELIVERY SYSTEM

Oral drug delivery is the most widely utilized route of administration among all the routes

that have been explored for the systemic delivery of drug via pharmaceutical products of

different dosage form. Oral route is considered most natural, uncomplicated, convenient and safe

due to its ease of administration, patient acceptance, and cost effective manufacturing process.

Pharmaceutical products designed for oral delivery are mainly immediate release type or

conventional drug delivery systems, which are designed for immediate release of drug for rapid

absorption. These immediate release dosage forms have some limitations such as,

1. Drugs with short half-life requires frequent administration, which increases chances of

missing dose of drug leading to poor patient compliance.

2. A typical peak- valley plasma concentration-time profile is obtained which makes

attainment of steady state condition difficult.

3. The unavoidable fluctuation in the drug concentration may lead to under

medication or over medication as the cells, valves fall or rise beyond the

therapeutic range.

4. The fluctuating drug levels may lead to precipitation of adverse effects especially

of a drug with small therapeutic index, whenever over medication occurs.

It is a reasonable assumption that drug concentration at the site of action is related to drug

plasma level and that, in the great majority of cases, the intensity of effect is some function of


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INTRODUCTION


drug concentration at the target site. The objective of the most therapeutic regimens is to rapidly

raise the plasma concentration to the required level and then to hold it constant for the desired

duration of treatment .The extent to which this situation can be achieved depends on many

factors, including the minimum effective concentration of the drug, the level at which side effects

occur, the dose administered, the rate of drug release from the dosage form, the rate of

elimination and the frequency of dosing. If the dose size and frequency of administration are

correct, therapeutic steady state levels of the drug can be achieved rapidly and maintained by

the repetitive administration of conventional oral dosage forms.

Traditionally, patient is expected to take medication during the daytime hours. Hence,

plasma levels are likely to fall to subtherapeutic levels overnight. Moreover the following major

deficiencies of conventional dosage forms can reduce the patients compliance to dose regimen.

Inconvenience and/or difficult use of drugs with very short duration of action or biological half-

life, thus needs frequent dosing.

Potential for peak-valley plasma levels, leading to toxicity and side effects and incomplete

therapy.

Instances of adverse effects, forgetfulness, and inconvenience of dosage forms.

Need for large systemic concentrations in order to achieve adequate concentration at target site

or action.

Potential variations in oral absorption due to variations in GIT pH profile, presence and type of

food and transit time in gut.

These above mentioned major deficiencies of drug therapy based on repetitive

administration of conventional single oral dosage form, In order to overcome the drawbacks of


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INTRODUCTION


conventional drug delivery system, several technical advancements have led to the development

of controlled drug delivery system that could revolutionize method of medication and provide a

number of therapeutic benefits.

Thus, various modified drug products have been developed to release the active drug from

the product at a controlled rate. The term controlled release drug products was previously used to

describe various types of oral extended-release dosage forms, including sustained release,

sustained action, prolonged action, slow release, long action, and retarded release.

The USP/NF presently recognizes several types of modified-release dosage forms,

1.Extended-release dosage forms (E.g. sustained release dosage forms, controlled release dosage

forms)

2.Delayed release dosage forms (e.g. enteric coated tablets)

Modified-release dosage forms:

It is defined as one for which the drug-release characteristics of time course and/ or

location are chosen to accomplish therapeutic or convenience objectives not offered by

conventional dosage forms such as solutions, ointments or compressed tablets and capsules.

Extended-release dosage form:

It is defined as the one that allows at least a twofold reduction in frequent dosing

compared to the drug presented in a conventional form (e.g., a solution or an immediate release

dosage form).

Sustained- release dosage forms:

It is defined as any drug or dosage form modification that prolongs the therapeutic

activity of the drug. It provides prolonged but not necessarily uniform release ofdrug.


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INTRODUCTION


The United States Pharmacopoeia has adopted the term extendedrelease whereas the

British Pharmacopoeia has adopted the term slow release. United States Food and Drug

Administration has adopted the term Prolonged release. However the literature survey indicates

that the most widely used terms today are sustained release & controlled release.

Figure 1.1: A hypothetical plasma concentrationtime profile from conventional multiple

and single doses of sustained and controlled delivery formulations.

Potential advantages of sustained release systems1:

1. Avoid patients complianceproblems.

2. Employ less total drug

a) Minimize or eliminate local side effects.

b) Minimize or eliminate systemic side effects.

c) Obtain less potentiation or reduction in drug activity with chronic use.


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INTRODUCTION


d) Minimize drug accumulation with chronic dosing.

3.Improve efficiency in treatment

a)

Cures or controls condition more promptly.

b) Improves control of condition i.e., reduced fluctuation in drug level.

c) Improves bioavailability of some drugs.

d) Make use of special effects, e.g. sustained-release aspirin for morning relief of

arthritis by dosing before bed time.

4.Economy i.e. reduction in health care costs. The average cost of treatment over an extended

time period may be less, with less frequency of dosing, enhanced therapeutic benefits and

reduced side effects. The time required for health care personnel to dispense and administer the

drug and monitor patient is also reduced.

Disadvantages:

1) Decreased systemic availability in comparison to immediate release

conventional dosage forms, which may be due to incomplete release, increased first-pass

metabolism, increased instability, insufficient residence time for complete release, site

specific absorption, pH dependent stability etc.

2) Poor in vitro-in vivo correlation.

3) Possibility of dose dumping due to food, physiologic or formulation variables or chewing

or grinding of oral formulations by the patient and thus, increased risk of toxicity.

4) Retrieval of drug is difficult in case of toxicity, poisoning or hypersensitivity reactions.

5) Of drugs normally administered in varying strengths.

6) Reduced potential for dosage adjustment Stability problems.


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7) More rapid development of tolerance and counseling.

8) Need for additional patient education and counseling.

Properties of drugs relevant to sustained release formulations:

The drug properties that influence the incorporation of the drug into a sustained release

dosage form can be classified as:

1) Physicochemical properties

2) Biological properties

Physicochemical properties are those that can be determined by in vitro experiments. Biological

properties are those that result from typical pharmacokinetic studies of absorption, distribution,

metabolism, and elimination characteristics of drugs.

Table 1.1: Drug properties suitable for sustained release2:

Property Explanation

1) Physicochemical properties

Dose Size If dose is greater than 0.5 g it is a poor candidate for a sustained

release system since the product size will be exceptionally large.

Aqueous solubility Extremes in aqueous solubility will be undesirable. For drugs with

low water solubility, they will be difficult to incorporate in sustained

release mechanism. The lower limit is 0.1 mg/ml. Drugs with very

high solubility are equally difficult to incorporate. pH dependant

solubility will be another problem.


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Partition Coefficient Drugs that are highly lipid soluble or very water-soluble i.e. extremes

in partition coefficient, will show either low flux in tissue or rapid flux

followed by accumulation in the tissues. Both cases are undesirable.

The value of K at which optimum activity observed is 1000/1 in

octanol/water.

Drug Stability As sustained release systems are designed to release their contents

over much of the length of GI tract, drugs, which are unstable in

environment of intestine, are poor candidates for sustained release.

2) Biological Properties

Absorption Drugs that are slowly absorbed or absorbed with variable absorption

rate are poor candidates for sustained release systems. Lower limit on

absorption rate constant is 0.25 h1

Distribution Drugs with high apparent volume of distribution, which in turn

influences rate of elimination, are poor candidates.

Metabolism As long as location, extent, and rates of metabolism are known and the

rate constant(s) for the processes are not too large, successful

sustained release systems can be developed.

Duration of action The biological half-life and hence duration of action plays a major

role. Drugs with biological half-life less than 2 hrs should not be used.

At the other extreme a drug with half-life of greater than 8 hrs have


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INTRODUCTION


inherently sustained action.

Therapeutic range Drugs with narrow therapeutic range requires precise control over the

blood levels of the drug, placing a constraint on sustained release

dosage form.

CLASSIFICATION OF SUSTAINED RELEASE

POLYMERIC DRUG DELIVERY SYSTEMS3,4

:

The various sustained release polymeric systems can be classified, depending upon the

mechanism controlling the drug release, as follows:

A.

Chemical ly controll ed systems

i)Biodegradable systems

ii)Drugpolymer conjugate

B.Di ff usion-controll ed systems

i)Membrane-reservoir systems

ii)Matrix systems

C.Dissolu tion controll ed system

i)Encapsulation/ reservoir type

ii)Matrix systems


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INTRODUCTION


A.Diffusion controlled systems:

Basically diffusion process shows the movement of drug molecules from a region of higher

concentration to one of lower concentration. This system is of two types:

a)Membrane-Reservoir type:

A core of drug surrounded by polymer membrane, which controls the release rate, characterizes

reservoir devices.

Advantages:

Zero order delivery is possible; release rate varies with polymer type.

Disadvantages:

Systems must be physically removed from implant sites.

Difficult to deliver high molecular weight compounds.

Increased cost per dosage unit, potential toxicity if system fails.

Ficks first law of diffusion describes the diffusion process.

J= -D dc/dx.

D = diffusion coefficient in area/time

dc/dx = change of concentration c with distance x

b)Matrix type:

Matrix system is characterized by a homogenous dispersion of solid drug in a polymer

mixture.

Advantages:


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INTRODUCTION


Easier to produce than reservoir or encapsulated devices, can deliver high molecular

weight compounds.

Disadvantages:

Cannot provide zero order release, removal of remaining matrix is necessary for

implanted system.

Higuchi has derived the appropriate equation for drug release from this system,

M = k t1/2

M = amount of drug released per unit area,

K= constant

B.Dissolution Controlled Systems:

a)Reservoir type:

Drug is coated with a given thickness coating, which is slowly dissolved in the content

of gastro intestinal tract. By altering layers of drugs with the rate controlling coats as shown in

figure no.1.2, a pulsed delivery can be achieved. if the outer layer is quickly releasing bolus dose

of the drug, initial levels of the drug in the body can be quickly established with pulsed intervals.


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INTRODUCTION


Figure 1.2: Schematic representation of diffusion controlled drug release reservoir.

b)Matrix type:

The more common type of dissolution controlled dosage forms as shown in figure

no.1.3. It can be either a drug impregnated sphere or a drug impregnated tablet, which will be

subjected to slow erosion.

Figure 1.3. Systematic representation of diffusion controlled drug release matrix system.

Advantages:


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INTRODUCTION


All the advantages of matrix dissolution system.

Removal from implant site is not necessary.

Disadvantages:

Difficulty to control kinetics owing to multiple processes of release.

Potential toxicity of degraded polymer must be considered.

D.Methods using Ion exchange

It is based on the drug resin complex formation when an ionic solution is kept in contact

with ionic resins. The drug from these complexes gets exchanged in gastrointestinal tract and

release with excess of Na+ and Cl-present in gastrointestinal tract.

E.Methods using osmotic pressure:

It is characterized by drug surrounded by semi permeable membrane and release governed

by osmotic pressure.

Advantages:

Zero order release rates are obtainable.

Preformulation is not required for different drugs.

Release of drug is independent of the environment of the system.

Disadvantages:

System can be much more expensive than conventional counter parts.

Quality control is more extensive than most conventional tablets.

F.pH

independent formulations:

A buffered controlled release formulation is prepared by mixing a basic or acidic drug with

or more buffering agents, granulating with appropriate pharmaceutical excipients and coating


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INTRODUCTION


with GI fluid permeable film forming polymer. When GI fluid permeates through the membrane

the buffering agent adjusts the fluid inside to suitable constant pH

thereby rendering a constant

rate of drug release.

Figure 1.4. Drug delivery from environmentally pH sensitive release systems

G.Altered density formulations:

Several approaches have been developed to prolong the residence time of drug delivery

system in the gastrointestinal tract.

High-density approach

Low-density approach

FABRICATION OF ORAL CONTROLLED RELEASE DELIVERY EMPLOYS

VARIOUS METHODS1,3,4

:

Hydrophilic matrix, Plastic matrix, Barrier resin beads, Fat embedment, Repeat action, Ion

exchange resin, Soft gelatin depot capsules and Drug complex.

Hydrophilic matrix system:

Drug delivery technologists usually tend to consider all hydrophilic delivery systems as

hydrogels. Hydrogels are hydrophilic macro molecular networks that after swelling maintain

their shape due to permanent links. The very high water content and special surface properties of


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INTRODUCTION


swollen form give them the ability to stimulate natural tissues. They have been used in controlled

drug delivery because of their good tissues compatibility and easy manipulation of swelling level

and their by solute permeability.

Hydrogel Based Drug Delivery Systems are classified as:

Diffusion controlled release system:

a)Reservoir System:

Figure 1.5. Hydrogel formation in Reservoir Systems

It consists of polymeric membrane surrounding a core containing the drug. The rate-limiting step

for drug release is diffusion through the outer membrane.

b)Matrix system:

The drug is dispersed throughout the three dimensional structure of the hydrogel. Release

occurs due to diffusion of the drug throughout the water filled pores.

Types:

Swellable

Non-swellable


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INTRODUCTION


Figure 1.6: Drug release from a matrix tablet

Swellable controlled release systems:

During the release life of swellable matrix system, three fronts are generally expected.

The swelling front, the boundary between the still glassy polymer and its rubbery:

1. State.

2. The diffusion front, the boundary in the gel layer between the solid as yet undisclosed,

drug and the dissolved drug.

3. The erosion front, the boundary between the matrix and the dissolution medium.


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INTRODUCTION


The measurement of front positions gives the possibility to determine three important

parameters related to the behavior of the matrix i.e. the rate of water uptake, the rate of drug

dissolution and the rate of matrix erosion associated with the movements of the swelling

front, diffusion front and erosion front respectively. These parameters are strictly linked to

the drug release kinetics from matrix.

Figure 1.7: Parameters definitions for swellable soluble matrix

Ds- Solvent diffusion co-efficient in the drug/polymer matrix.

Dd-Drug diffusion co-efficient in the swollen polymers.

CsDrug solubility at the drug core interface ( R ).

C*- Drug volume fraction at the gel /solution interface.

CPolymer volume fraction at R.

CdPolymer volume fraction at S.

CcpPolymer volume fractioning in the glassy core.

CcdDrug volume fraction in the glassy core .


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INTRODUCTION


Non- swellable controlled release systems.

The systems are hollow containing an inner core of the drug surrounded in a water

insoluble polymer membrane. The polymer can be applied by coating or by wet granulation

technique. The drug release mechanism across the membrane involves its portioning into the

membrane with subsequent release into the surrounding fluid by diffusion.

Table No. 1.2: Characteristics of major classes of sustained release drug delivery system3

Type of System Mechanism of drug

release

Advantages Limitations

A) Chemically controlled systems

1.Biodegradable

system

Matrix-forming polymer

contains hydrolytically or

enzymatically labile

bonds and drug is

uniformly dissolved or

dispersed in this matrix.

Erosion of polymer by

hydrolysis or enzymatic

cleavage.

Erosion

process has a

direct effect on

drug release

Difficult to achieve

targeted drug delivery

system.

2. Drug-Polymer

Conjugates

Drug molecules

chemically bonded to a

polymer backbone. The

Provides the

possibility for

sustaining the

Improper attachment of

drugs to carriers can alter

rate of drug excretion


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INTRODUCTION


drug is released through

hydrolytic or enzymatic

cleavage of these bonds

drug release

over a

prolonged

period

from body

B. Diffusion-controlled systems

1. Membrane-

Reservoir

System

Follows either a solution

diffusion mechanism or

an osmotic mechanism

Osmotic pressure

can control the

drug release.

Observed only in non-

porous membranes

2. Matrix system Drug release from matrix

system can occur by any

of these mechanisms:

Diffusion, Erosion or

Swelling.

One of the least

complicated

approaches to

manufacture the

sustained release

dosage forms

1.first-order release

behavior with

continuously

diminishing release

rate.

2.Increasing

diffusional resistance

and decreasing area at

the diffusion front.

C. Dissolution controlled system

Encapsulation Drug particles are

covered with layer of

polymers. As polymer

Drug can be

delivered when

needed.

Immediate release

cannot be achieved.

High cost of coating


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INTRODUCTION


erodes drug gets released. increased.

MATRIX SYSTEMS1,5,6

:

Matrix system is formulated in such manner as to make the contained drug available over

an extended period following administration. A typical controlled release system is designed to

provide constant or nearly constant drug levels in plasma with reduced fluctuations via slow

release over an extended period of time. In practical terms, an oral controlled release should

allow a reduction in dosing frequency as compared to when the same drug is presented as a

conventional dosage form.

The following table (Table No. 1.3) summarizes the characteristics of various types of

matrix systems.

Table 1.3: The characteristics of various types of matrices are:

Slow eroding matrix Hydrophilic matrix Plastic matrix

Mechanism of The portion of the drug Two competing The drug is

drug release intended to have mechanisms: Fickian granulated

sustained action is diffusional release & with an inert

combined with lipid or relaxation release. plastic material

cellulosic material and such as

processed into granules polyethylene,

that can be placed into polyvinyl

capsules or tableted. acetate or


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INTRODUCTION


When these granules are

combined with granules

of drug prepared without

the special lipid or

cellulosic excipients, the

untreated portion

provides the immediate

drug effect, and the

treated portion provides

the prolonged effect.

polymethacryla

te, and the

granulation is

compressed

into tablets

Example of

drug

candidates

SLOW-K (Summit), a

KCl sugarcoated

sustained release tablet

containing KCl in a wax

matrix.

Sparingly soluble

drug

Gradumet

(Abbott)

Matrix

characteristics

Insoluble, erodible Hydrophilic Insoluble, inert

Material Carnauba wax, Stearyl

alcohol, Stearic acid,

Polyethylene glycol,

Castor wax, Polyethylene

Methylcellulose

(400cps, 4000cps),

Hydroxyethylcellulo

se, HPMC, Sodium

Polyethylene,

polyvinyl

chloride,

methyl


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INTRODUCTION


glycol monostearate, CMC, Sodium acrylates-

Triglycerides alginate, methacrylate

Galactomannose copolymer,

Carboxypolymethyle ethyl cellulose.

ne

Advantages of the matrix systems: (Robinson J.R. and Lee V.H.L., 1987)

Easy to manufacture.

Versatile, effective, low cost. Can be made to release high molecular weightcompounds.

Reproducible release profile.

Since the drug is dispersed in the matrix system, accidental leakage of the total drug component

is less likely to occur, although occasionally, cracking of the matrix material can cause

unwanted release.

Disadvantages of the matrix systems: (Robinson J.R. and Lee V.H.L., 1987)

The remaining matrix must be removed after the drug has been released

The drug release rates vary with the square root of time. Release rate continuously

diminishes due to an increase in diffusional resistance and/or a decrease in effective area at the

diffusion front.

APPROACHES FOR PREPARATION OF MATRIX DOSAGE FORMS:

There are many approaches for preparing matrices for sustained drug delivery.

Table No. 1.4 summarizes common approaches for the same7.


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INTRODUCTION


Method Features Advantages Limitations

Melt

Granulati

on

Granules prepared

by melting all the

ingredients together

and then screening

the congealed mass

through appropriate

mesh.

Useful for enhancing

solubility and hence

dissolution of poorly

water soluble drugs

and for modifying

release

characteristics of

drugs delivered

transdermally.

1. No need of

solvents.

2. Fewer processing

steps.

3.No need of high

compression.

4.Uniform dispersion

of fine particles

occurs.

5.Stability at varying

pH and moisture

levels

1.High energy

requirement.

2.Not suitable for

thermosensitive

materials including low

melting binders.

3.Not suitable for

blends containing high

melting binders,

thermosensitive drugs

and/ or additives.

Direct Drug embedded 1. More economic 1. Segregation of

Compressi matrices prepared by due to fewer steps, particles.

on direct compression of less equipments &2. Not suitable for

blend of drug andless labour.


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INTRODUCTION


additives and release

retardant

2. Less time

consuming.

3.No batch-to-batch

variation.

4.Useful for moisture

sensitive and

thermosensitive

drugs.

drugs having large

doses.

3.Development of

static charges during

blending.

4.Difficulty in uniform

distribution of color.

Wet Granules containing 1. Less energy is 1. Solvents are

Granulatidrug are prepared required. required.

onusing adhesive

2. Useful for 2. High compression is

properties ofthermosensitive required.

binders.drugs.

MECHANISM OF DRUG RELEASE FROM MATRIX DEVICES3,5

1.Dissolution controlled release:

Controlled release oral products employing dissolution as a rate limiting step are in

principle simplest to prepare. Even if the drug has a rapid rate of dissolution it is possible

incorporate it into a tablet with a carrier, which has a slow rate of dissolution.


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INTRODUCTION


We assume the dissolution process where the rate of diffusion from the surface to the

bulk of the solution through an unstirred liquid fill is the rate limiting step. In this case the

dissolution process at study would be described by the Noyes-Whitney equation:

dc/dt = kDA(Cs-C)1

dc/dt is the dissolution rate

KD is the dissolution rate constant

Cs is the saturation solubility of the drug and

C is the concentration of the drug in the bulk of the solution.

In relation diffusion expression kD equals to D/V.I.

From the above expression it can be seen that rate of dissolution i.e, availability is

approximately proportional to the solubility of the drug in the dissolution media (Cs) provide

constant surface area and diffusion path length are maintain.

This equation predicts constant dissolution rate as long as enough drug is present to

maintain Cs constant and provided surface area does not change. For spherical particles the

change in surface area can be related to the weight of the particle and substituted in the diffusion

equation to give an expression that related dissolution to the weight remaining (W).

W01/3- W1/3 = K1 D.2

W0 is the initial weight.

K1

D is the cube root dissolution expression.

The above equation described dissolution rate of spherical particles when surface area

and diffusional path are changing.

The common forms of dissolution controlled formulations for into two categories:


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INTRODUCTION


a) Encapsulation dissolution control.

b) Matrix dissolution control.

Encapsulation dissolution control:

These methods generally involve coating individual particles of drug with a slow

dissolving material. The coated particles can be directly compressed into tablets as in space tabs

or placed in capsules as in spansule products. Since the time required for dissolution of the coat

is a function of thickness and aqueous solubility, one can obtain repeat or sustained action by

employing a narrow or a wide spectrum of coated particles of varying thickness respectively.

Matrix dissolution control:

Those methods involve compressing the drug with a slowly dissolving carrier into a

tablet form. Here the rate of drug availability is controlled by the rate of penetration of

dissolution fluid into the matrix. This in turn can be controlled by porosity if the tablet matrix,

the presence of hydrophobic additives and the wettability of the tablet and particle surface.

1.DIFFUSION CONTROLLED RELEASE:

Diffusion controlled release products are basically of two types

a) Encapsulated diffusion control

b) Matrix diffusion control

Encapsulated diffusion control:

In this system water insoluble polymeric material encases a core of drug. Drug

will partition into the membrane and exchange with the fluid surrounding the particles or tablet.

The release rate is given by equation.


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INTRODUCTION


dm/dt = ADKC/I..(3)

A is the area

D is the diffusional coefficient

K is the partition coefficient of the drug between the membrane and drug core

I is the diffusional path length

C is the concentration difference across the membrane.

An important parameter in the above equation is the partition coefficient which is defined

as the concentration, of the drug in the membrane over the concentration of the drug in the core.

If the partition coefficient is high, the core will be depleted of the drug release rate all the terms

in the right hand side of the above equation must be held constant.

Methods to develop reservoir type devices include press coating, air suspension coating

techniques. Microencapsulation process is a commonly used procedure to coat the drug articles

to be incorporated.

Matrix diffusion control:

In this type a solid drug is dispersed in an insoluble matrix and the rate of release of drug

is independent if the rate of diffusion and not on the rate of solid dissolution. The equation

describing drug release from this system has been derived by Higuchi.

Q = [ (DE/T) (2A-ECs) Cst] ......... 4

Q is the diffusion coefficient of drug released per unit area at timet

D is the diffusion coefficient of drug in release medium

E is the porosity of matrix


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INTRODUCTION


Cs solubility of drug in the release medium

T is the tortuosity of matrix

A is the concentration of drug in the tablet expressed as gm/ml

The assumptions made in above equation are:

1. A pseudo steady state is maintained during release

2. A >> Cs i.e., excess solute is present

3. C = 0 in solution at all times (perfect sink)

4. Drug particles are much smaller than matrix

5. The diffusion coefficient remains constant

6. No interaction occurs between drug and matrix.

For the purpose of data treatment the above equation is usually reduced to Q = Kt1/2

Where K is a constant so that the plot of amount drug released versus the square root of

time should be linear if the system is diffusion controlled.

Depending on the properties of the matrix and the polymer system, deviation from

constant release can occur. For example in the case of insoluble matrix, the drug may have to

diffuse through tortuous correction factor is added to the release equation.

The most popular drug delivery system has been matrix system containing uniformly

dissolved or dispersed drug such as tablets and granules, because of its ease of fabrication.

However the release behavior is inherently first order in nature with continuously diminishing

release rate for all three standard geometries: slab, cylinder and sphere. This is the result of

increase in diffusional resistance and a decrease in effective area at the diffusion front as drug


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INTRODUCTION


release proceeds. Use of zero order delivery systems will optimize the therapy by maintaining

dug concentration for prolonged periods.

Methods for altering the kinetics of the drug release from the inherent first order behavior

to zero order have involved the use of geometry factors, erosion, dissolution, control, swelling

mechanisms, non-uniform drug loading and matrixmembrane combinations.

Swelling phenomena are generally encountered in both hydrophilic and hydrophobic

matrices during release of the entrapped water soluble drugs in aqueous environment. The

release of water soluble drugs from initially dehydrated hydrogels generally involves the

simultaneous absorption of water and desorption of drug via a swelling controlled diffusion

mechanism.

In case where the sorption process is completely governed by the rate of the polymer

relaxation the so called case 11 transport, characterized by linear time dependence in both the

amount diffused and the penetrating swelling front position results. In most system the

intermediate situation, which is often termed non- Fickian or anomalous diffusion will prevail

wherever the rates of diffusion and polymer relaxation are comparable.

By Korsemeyer and Peppas equation one can express the fraction released Mt/M as a

power function of timet for the short time period.

Mt/M = K1tn

Where K is a constant characteristic of the system and n is an exponent characteristic

of the mode of transport. For n = 0.5, the drug release follows the well known Fickian diffusion

mechanism. For n > 0.5 non- Fickian or anomalous diffusion behavior is generally observed. The


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INTRODUCTION


special case of n= 1 describes a case 11 transport mechanism; the drug release from such devices

having constant geometry will be constant (zero order).

Usually non Fickian release is observed till the polymer chains rearrange to an

equilibrium state. Once the hydrogel matrix is significantly hydrated, drug release becomes

Fickian. The relative importance of relaxation and diffusion can in principle be estimated with

the Deborah number, De which is the ratio of the characteristic relaxation time to a

characteristic diffusion time ( = L2/D) where L is length.

De = /

When De


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AIM AND OBJECTIVE


2.AIM AND OBJECTIVE

The basic goal of therapy is to achieve a steady state blood or tissue level that is

therapeutically effective and non-toxic for an extended period of time. Sustained

release drug delivery systems, with an aim of improved patient compliance, better

therapeutic efficacy, less side effects and reduced dosage regimen with less toxicity

for treatment for many acute and chronic diseases.

Anti hypertensive drugs are used for the treatment of hypertension. Telmisartan has

been demonstrated to be superior to previous peptide receptor antagonists and

angiotensin converting enzyme (ACE) inhibitors because of its enhanced specificity,

selectivity and tolerability.

Matrix tablets are very useful in the field of healthcare for sustained release dosage

regimen.

Keeping this in view, the present investigation has been aimed at designing suitable

sustained release matrix tablets using polymers like HPMC K100M, Ethyl cellulose,

Xanthan Gum.

The major objectives of the investigation are as follows:

Preparation of calibration curve.

To perform compatibility studies by using IR spectroscopy.

To perform preformulation studies like flowing properties and bulking density for

powders of drug and polymers.

To evaluate prepared formulations for physical parameters like weight variation,

friability and hardness etc.


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AIM AND OBJECTIVE


To formulate matrix tablets of Telmisartan by wet granulation method by using different

polymer like Hydroxypropyl methylcellulose K100M (HPMC K100M), Ethyl cellulose,

Xanthan Gum.

To ascertain the release mechanics and kinetics of drug release from compressed matrix

tablets.

To perform stability studies as per ICH guidelines.

BASICS FOR DRUG SELECTION AND DOSAGE SELECTION.

For many drugs, the optimal therapeutic response is observed only when adequate

blood levels are achieved and maintained with minimum variations, (the matrix

tablets will give more consistent blood levels).

Drugs with biological half-life 2-4 hrs are viewed as suitable candidate for sustained

release dosage form. So it is suitable to deliver this drug in SR dosage form.

Generally a lower daily dose of Telmisartan potassium may be sufficient for long-

term administration (40 mg).

Maintenance of dose is usually 40mg per day.


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PLAN OF WORK

3.PLAN OF WORK

Literature Survey

Selection of drug candidate

Procurement of Drug and Excipients

Characterization of Telmisartan

- Melting Point

- UV

- IR

- DSC

Preparation of granules

(Wet granulation method)

Evaluation of granules

Tests for compatability Tests for bulk properties

-Infra Red Spectroscopy - Angle of repose,


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PLAN OF WORK

-Differential scanning colorimetry - Bulk density

Compression of granules obtained by wet

granulation method into tablets

Evaluation of Tablets

-Thickness and Diameter

-Weight variation

-Hardness

-Drug content

-

Friability

-In-Vitro Release Studies

Data Compilation and

Analysis of result.

-Tapped density

-Flow Rate,

-Carrsindex


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LITERATURE SURVEY

4.LITERATURE SURVEY

Saptarshi D., et al. An attempted was to formulate the oral sustained release metformin

hydrochloride matrix tablets by using hydroxyl methyl cellulose polymer (HPMC) as rate

controlling factor and to evaluate drug release parameters as per various release kinetic models.

It is observed that the basic goal of therapy in the development of metformine hydrochloride

release dosage form is to increase bioavailability; reduce risk of hospitalization, deliver drug at a

near constant rate for approximately 12hrs; independent of food intact and gastrointestinal pH.

The dry granulation technique was used to compress the tablet as powder showed the poor

flowability; less cohesiveness during direct compression and due to moisture sensitivity and

tendency to hydrolyte, wet granulation technique was not selected for the present work8.

Dhirendra K, et al. The aim of the present study was to formulate once daily sustained

release matrix tablets of Stavudine to increase therapeutic efficacy, reduce frequency of

administration and improve patient compliance. The sustained release tablets were prepared by

direct compression and formulated using different drug:polymer ratios, formulations such as F1

to F15. Hydrophilic polymers like Hydroxypropyl methylcellulose (HPMC), Carboxy methyl

cellulose (CMC) and starch 1500 were used. Compatibility of the drug with various excipients

was studied. The compressed tablets were evaluated and showed compliance with

pharmacopoeial standards9.

Madhusmruti K, et al. The aim of the present work was to develop sustain release

matrix formulation of Propanolol hydrochloride and investigate the effects of both hydrophilic

and hydrophobic polymer on in-vitro drug release. Matrix tablets were prepared by direct

compression method using different concentrations of Hydroxypropyl methylcellulose (HPMC)

and Ethyl Cellulose (EC). Prepared formulations were subjected to various studies like hardness,


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LITERATURE SURVEY

friability, thickness, %drug content, weight variation, dynamic of water uptake and erosion etc.

Tablets were subjected to in-vitro drug release in 0.1N HCl (pH 1.2) for first 2 hours followed by

phosphate buffer (pH 6.8) remaining time10

.

Jayaprakash S., et al . The sustained release (SR) tablets of Ambroxol Hydrochloride

were prepared by Wet granulation method. The effect of hydrophilic matrices on the behavior of

Ambroxol hydrochloride using different polymers and their combinations. The prepared tablets

were evaluated for physical characteristics such as Hardness, Thickness, Friability, Weight

Variation, Content uniformity and in-vitro release behavior. The drug release from the optimized

formulation was found to follow zero order kinetics11.

Umesh D.S, et al . The objective of the present study was to develop once daily

sustained release tablets of Aceclofenac by wet granulation using carboxypolymethylene

polymer. The drug excipient mixtures were subjected to preformulation studies while the tablets

were subjected to physicochemical studies, in vitro drug release, stability studies and validation

studies12

.

Raghavendra R.N.G, et al. The main objective of the present work was to develop

sustained release matrix tablets of water soluble Tramadol hydrochloride using different

polymers viz. Hydroxypropyl methylcellulose (HPMC) and natural gums like karaya gum (KG)

and carrageenan gum (CG). Varying ratios of drug and polymer like 1:1 and 1:2 were selected

for the study. After fixing the ratio of drug and polymer for control the release of drug upto

desired time, the release rates were modulated by combination of two different rates controlling

material and triple mixture of three different rate controlling material13

.


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LITERATURE SURVEY

Anton S et al. The objective of the present work was to develop sustained release matrix

tablets of Ondansetron Hydrochloride(5mg) formulated employing Hydroxy propyl Methyl

Cellulose(HPMC), polymer and the sustained release behavior of the tablets was investigated.

Tablets were prepared by wet granulation methods14

.

Parasuram R.R, et al . The aim of the present study was to design an oral sustained

release matrix tablet of Glipizide and to optimize the drug release profile using response surface

methodology. The tablets were prepared by the wet granulation method using HPMC K100 and

Eudragit L 100 as matrix forming polymers. A central composite design for 2 factors at 3 levels

each was employed to systematically optimized drug release profile. HPMC K100 and Eudragit

L 100 were taken as the independent variables. The dependent variables selected were % of drug

released in 2 h (release 12 h)15.

Kalyani C, et al. The objective of the study was to design oral sustained release matrix

tablets of Zidovudine using Hdroxypropyl methylcellulose (HPMC)K 4M, Guar Gum and Ethyl

Cellulose as the retardant polymers and study the effect of various formulation factors such as

polymer proportion, polymer type and effect of filler type on the in-vitro release of drug. Matrix

tablets were by Wet granulation method and prepared tablet were evaluated weight variation,

%friability, hardness, thickness and in-vitro dissolution studies. All the granules and

formulations showed compliance with pharmacopeial standards.In-vitro release studies revealed

that the release rate decrease with increase polymer proportion and hydrophobic polymers retard

the drug release more than hydrophilic polymers16

.

Tapan K.P, et al . The aim of the current study was to design an oral sustained release

matrix tablet of Metformin HCl and to optimize the drug release profile using response surface

methodology. Tablets were prepared by non-aqueous wet granulation method using HPMC K


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LITERATURE SURVEY

15M as matrix forming polymer. A central composition design for 2 factors at 3 levels each was

employed to systematically optimize drug release profile. HPMC K 15M (X1) and PVP K 30

(X2) were taken as the independent variables. The dependent variable selected were % of drug

release in 1 hr (rel1hr), % of drug release in 8 hr (rel8hr), and time to 50% drug release (t50%)17

.

Basak S. C et al . Monolithic matrix tablets of Ambroxol Hydrochloride were formulated

as sustained release tablets employing Hydroxypropyl methylcellulose polymer, and the

sustained release matrix tablets containing 75 mg Ambroxol hydrochloride were developed using

different drug polymer ratios of Hydroxy propyl Methyl Cellulose. Tablets were prepared by

direct compression. Formulation was optimized on the basis of acceptable tablet properties and

in vitro drug release18

.

Varshosaz J et al . The objective of this work was to develop matrix sustained release

tablets of highly water-soluble Tramadol HCl using natural gums Xanthan [X gum] and Guar [G

gum] as cost-effective, nontoxic, easily available and suitable hydrophilic matrix systems

compared with extensively investigated hydrophilic matrices (ie, Hydroxypropyl methylcellulose

[HPMC]/Carboxymethyl cellulose [CMC] with respect to in-vitro drug release rate) and

hydration rate of the polymers. Matrix tablets of Tramadol (dose 100 mg) were produced by

Direct compression method19

.

Muhammad K.S et al . The present study was conducted to investigate the low viscosity

grades of Hydroxypropyl methylcellulose(HPMC), and ethyl cellulose(EC), in sustaining the

release of water insoluble drug, Naproxen from the matrix tablets. Both HPMC and EC were

incorporated in the matrix system separately or in combinations by wet granulation technique. In

vitro dissolution studies indicated that EC significantly reduced the rate of drug release


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LITERATURE SURVEY

compared to HPMC in 12hr testing time. But, no significant difference was observed in the

release profiles of matrix tablets made by higher percentages of EC20

.

Yeole P.G. et al . In the present investigation, an attempt has been made to increase

therapeutic efficacy, reduce frequency of administration, and improve patient compliance, by

developing sustained release matrix tablets of Diclofenac sodium. Sustained release matrix

tablets of Diclofenac sodium, were developed by using different drug:polymer ratios, such as

F1(1:0:12), F2(1:0:16), F3(1:0:20), F4(1:0:24) and F5(1:0:28). Xanthan gum was used as matrix

former, and microcrystalline cellulose as diluents. Compressed tablets were evaluated for

uniformity of weight, content of active ingredient, friability, hardness, thickness, in vitro

dissolution using basket method and swelling index21

.

Hosseinali T et al. A sustained release tablet formulation should ideally have a proper

release profile insensitive to moderate changes in tablet hardness that is usually encountered in

manufacturing. In the study, matrix Aspirin (acetylsalicylic acid) tablets with ethyl cellulose

(EC), Eudragit RL100, Eudragit S100 were prepared by direct compression. The release

behaviors were then studied in two counterpart series of tablets with hardness difference of three

Kp units, and compared by non-linear regression analysis22

.

Raghuram R.K et al . The objective of the present study was to develop once-daily

sustained- release matrix tablets of Nicorandil, a novel potassium channel opener used in

cardiovascular diseases. The tablets were prepared by the wet granulation method. Ethanolic

solutions of ethyl cellulose(EC), Eudragit RL-100, Eudragit RS-100, and poly vinyl pyrrolidone

were used as granulating agents along with hydrophilic matrix materials like Hydroxy propyl

Methyl Cellulose(HPMC), sodium carboxy methyl cellulose, and sodium alginate23

.


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LITERATURE SURVEY

Chandira M. et al . The present investigation attempt has been made increase therapeutic

efficacy , reduce frequency of administration and improve patient Compliance, by developing

sustained release matrix tablets of Zidovudine, Were developed by using drug polymer ratio

kollidon SR, HPMC k15M, HPMC K100M as matrix former.aii lubricated formulation were

compressed by direct compression and wet granulation method24

.

Krishnaiah Y.S.R. et al. The objective of the present study is to carry out

pharmacokinetic evaluation of oral controlled release formulation (guar gum-based three layer

matrix tablets) containing highly soluble Metoprolol tartrate as a model drug. Six healthy

volunteers participated in the study, and a two way crossover design was followed. The plasma

concentration of Metoprolol tartrate was estimated by reverse-phase HPLC. The

pharmacokinetic parameters were calculated from the plasma concentration of metoprolol

tartrate versus time data25

.

Suvakanta D. et al . In this paper were reviewed mathematical models used to determine

the kinetic of drug release from drug delivery system the quantitative analysis of the values are

obtained in dissolution/ release rate is easier when mathematical formula used to describe the

process. The mathematical modeling can optimize to design therapeutic design of therapeutic

device to yield information on the various efficacy of various release models26

.

Ganesan V. et al ., The objective of the study was to develop guar gum matrix tablets for

oral controlled release of Ambroxol hydrochloride. According to the theoretical release profile

calculation, a twice daily sustained release formulation should release 19.6 mg of Ambroxol

hydrochloride in 1 hour like conventional tablets, and 5.2 mg per hour upto 12 hours. Ambroxol

hydrochloride matrix tablets containing either 30%wt/wt of low viscosity (F-III), 25% w/w


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LITERATURE SURVEY


medium viscosity (F-VI) or 20 %wt/wt high viscosity (F-IX) guar gum showed sustained

release27

.

Gothi G.D. et al. In the present investigation an attempt was made to reduce the

frequency of dose administration, to prevent nocturnal heart attack and to improve the patient

compliance by developing extended release (ER) matrix tablet of metoprolol succinate. The

effect of concentration of hydrophilic (hydroxypropyl methylcellulose [HPMC K 100 M],

Xanthan gum) on the release rate of metoprolol succinate was studied28

.

Keny R.V. et al . The present study was aimed to develop once daily extended release

matrix tablets of minocycline hydrochloride, using hydroxyl propyl methyl cellulose either alone

or in combination with ethyl cellulose as the matrix material in different proportions. The

formulated tablets were also compared with a marketed product. The results of the dissolution

study indicate that formulations FC-IV, FC-V, FC-VI, shows maximum drug release upto 24 hr.

Drug release from matrix occurred by combination of two mechanisms diffusion of tablet matrix

and erosion of tablet surface which was reflected from Highuchis model and Erosion plot29

.

Tabandeh H. et al . A sustained release tablet formulation should ideally have a proper

release profile insensitive to moderate changes in tablet hardness that is usually encountered in

manufacturing. In the study, matrix Aspirin (acetylsalicylic acid) tablets with ethyl cellulose

(EC), Eudragit RL100, Eudragit S100 were prepared by direct compression. The release

behaviors were then studied in two counterpart series of tablets with hardness difference of three

Kp units, and compared by non-linear regression analysis30

.


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LITERATURE SURVEY


Sasidhar R.L.C et al. In the present investigation an attempt has been made to increase

therapeutic efficacy, reduced frequency of administration and improved patient compliance by

developing controlled release matrix tablets of Telmisartan. Telmisartan was formulated as oral

controlled release matrix tablets by using poly (ethylene oxides) {Polyox WSR 303}.The aim of

this study was to investigate the influence of polymer level and type if fillers namely lactose

[soluble filler], microcrystalline cellulose and anhydrous dibasic calcium phosphate [insoluble

fillers] on the release rate and mechanism of Telmisartan from

matrix tablets31

.

Chopra S et al. The aim of the present research work was to systemically device a model

of factors that would yield an optimized controlled release tablet dosage form of an anti-

hypertensive agent, Telmisartan. Independent variables such as the amount of the release

retardant polymers- Methocel K15M(X1), Methocel K100M(X2) and Sodium carboxy methyl

cellulose(X3) were optimized using a 3-Factor, 3-level Box-Behnken statistical design. The

dependent variables selected were the burst release in 15min (Y1), cumulative % release of

Telmisartan after 60 min. (Y2) and hardness (Y3) of the tablets32

.

Shruti C et al. The aim of the present research work was to systemically device a model

of factors that would yield an optimized sustained release tablet dosage form of an anti-

hypertensive agent, Telmisartan, using response surface methodology by employing a 3- Factor,

3-level Box-Behnken statistical design. Independent variables studied were the amount of the

release retardant polymers-HPMC K15M(X1), HPMC K100M(X2) and Sodiumcarboxy

methylcellulose(X3). The dependent variables selected were the burst release in 15min.(Y1),

cumulative % release of Telmisartan after 60 min. (Y2) and hardness(Y3) of the tablets with

constraints on the Y2= 31-35%33

.


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DRUG PROFILE

DRUG PROFILE

TELMISARTAN34-38

Telmisartan is in the drug class of angiotensin receptor blockers (ARBs) and is prescribed for the

treatment of high blood pressure, reducing the risk of heart attack, stroke, or death from

cardiovascular causes, Telmisartan is an angiotensin II receptor antagonist (ARB) used in the

management of hypertension. Generally, angiotensin II receptor blockers (ARBs) such as

Telmisartan bind to the angiotensin II type 1 (AT1) receptors with high affinity, causing

inhibition of the action of angiotensin II on vascular smooth muscle, ultimately leading to a

reduction in arterial blood pressure. Recent studies suggest that Telmisartan may also have

PPAR-gamma agonistic properties that could potentially confer beneficial metabolic effects

Structure of Telmisartan

Chemical Name:-

[4-[[4-methyl-6-(1-methylbenzimidazol-2-yl)-2-propylbenzimidazol-1-yl]methyl] 1,1 biphenyl]2 carboxylic acid.

Molecular Formula:- C33H30N4O2

Molecular Weight:- 514.61 DaltonsDescription:- White to off-white crystalline powder.

Melting range:- Between 265oC - 272

oC

Solubility:- Practically insoluble in water, slightly soluble in methanol, sparingly soluble in

methylene chloride, it dissolves in 1M sodium hydroxide.

Partial coefficient:- The Octanol/buffer partial coefficient (log P) for Telmisartan is

approximately 3.20

Storage & Stability:- Stored in well-closed, light-resistant containers at 5-30C. When stored


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DRUG PROFILE

under these conditions, Telmisartan generally is stable for 24 months after the date of

manufacture.

Indication:- For the treatment of hypertension

Clinical Pharmacology:-Telmisartan is an orally active nonpeptide angiotensin II antagonist that acts on the AT1 receptor

subtype. New studies suggest that telmisartan may also have PPAR agonistic properties thatcould potentially confer beneficial metabolic effects. This observation is currently being

explored in clinical trials. Angiotensin II is formed from angiotensin I in a reaction catalyzed by

angiotensin-converting enzyme (ACE, kininase II). Angiotensin II is the principal pressor agentof the renin-angiotensin system, with effects that include vasoconstriction, stimulation of

synthesis and release of aldosterone, cardiac stimulation, and renal reabsorption of sodium.

Telmisartan works by blocking the vasoconstrictor and aldosterone secretory effects of

angiotensin II.

Mechanism of Action:-Telmisartan interferes with the binding of angiotensin II to the angiotensin II AT1-receptor by

binding reversibly and selectively to the receptors in vascular smooth muscle and the adrenal

gland. As angiotensin II is a vasoconstrictor, which also stimulates the synthesis and release ofaldosterone, blockage of its effects results in decreases in systemic vascular resistance.

It does not inhibit the angiotensin converting enzyme, other hormone receptors, or ion channels.

Pharmacokinetic properties;

Absorption

Absorption of telmisartan is rapid although the amount absorbed varies. The mean absolutebioavailability for telmisartan is about 50 %. When telmisartan is taken with food, the reduction

in the area under the plasma concentration-time curve (AUC0-) of telmisartan varies from

approximately 6 % (40 mg dose) to approximately 19 % (160 mg dose). By 3 hours after

administration, plasma concentrations are similar whether telmisartan is taken fasting or withFood.

Linearity/non-linearityThe small reduction in AUC is not expected to cause a reduction in the therapeutic efficacy.There is no linear relationship between doses and plasma levels. Cmax and to a lesser extent

AUC

increase disproportionately at doses above 40 mg.

Distribution

Telmisartan is largely bound to plasma protein (>99.5 %), mainly albumin and alpha-1 acid

glycoprotein. The mean steady state apparent volume of distribution (Vdss) is approximately 500

Biotransformation

Telmisartan is metabolised by conjugation to the glucuronide of the parent compound. Nopharmacological activity has been shown for the conjugate.

EliminationTelmisartan is characterised by biexponential decay pharmacokinetics with a terminal eliminateion half-life of >20 hours. The maximum plasma concentration (Cmax) and, to a smaller extent,

the area under the plasma concentration-time curve (AUC), increase disproportionately with

dose. There is no evidence of clinically relevant accumulation of telmisartan taken at the

recommended dose. Plasma concentrations were higher in females than in males, withoutrelevant influence on efficacy.

After oral (and intravenous) administration, telmisartan is nearly exclusively excreted with the


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DRUG PROFILE

faeces, mainly as unchanged compound. Cumulative urinary excretion is 99.5%), mainly albumin and a1-acid glycoprotein. Binding is

not dose-dependent.

Biot8ransformationMinimally metabolized by conjugation to form a pharmacologically inactive acylglucuronide;

the glucuronide of the parent compound is the only metabolite that has been identified in humanplasma and urine. The cytochrome P450 isoenzymes are not involved in the metabolism of

telmisartan.

Dosage and Administration:The usually effective dose telmisartan is 4080 mg once daily. Some patients may already

benefit at a daily dose of 20 mg. In cases where the target blood pressure is not achieved,

telmisartan dose can be increased to a maximum of 80 mg once daily.

ContraindicationsTelmisartan is contraindicated during pregnancy. Like other drugs affecting the renin angiotensin

system (RAS), telmisartan can cause birth defects, stillbirths, and neonatal deaths. It should notbe taken by breastfeeding women since it is not known whether the drug passes into the breast

milk.

Side effectstachycardia andbradycardia (fast or slow heartbeat), hypotension (low blood pressure), edema

(swelling of arms,legs, lips, tongue, or throat, the latter leading to breathing problems), and

allergic reactions.


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EXCIPIENTS PROFILE

4.2.EXCIPIENTS PROFILE

Hypromellose (Hydroxy Propyl Methyl Cellulose)

A.

Nonproprietary Names

BP: Hypromellose

JP: Hydroxypropyl methylcellulose

PhEur: Hypromellosum

USP: Hypromellose

B.Synonyms

Benecel MHPC; E464; hydroxypropyl methylcellulose; HPMC; Methocel;

methylcellulose propylene glycol ether; methyl hydroxypropylcellulose;Metolose; Tylopur.

C.Chemical Name and CAS Registry Number

Cellulose hydroxypropyl methyl ether [9004-65-3]

D.Molecular Weight

Molecular weight is approximately 10 0001 500 000.

E.Structural Formula


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EXCIPIENTS PROFILE

Where R is H, CH3, or CH3CH (OH) CH2

F.Functional Category

Coating agent; film-former; rate-controlling polymer for sustained release; stabilizing

agent; suspending agent; tablet binder; viscosity-increasing agent.

G.Applications in Pharmaceutical Formulation or Technology

Hypromellose is widely used in oral, ophthalmic and topical pharmaceutical

formulations. In oral products, hypromellose is primarily used as a tablet binder, in film-coating,

and as matrix for use in extended-release tablet formulations. Concentrations between 2% and

5% w/w may be used as a binder in either wet- or dry-granulation processes. High-viscosity

grades may be used to retard the release of drugs from a matrix at levels of 1080% w/w in

tablets and capsules. Depending upon the viscosity grade, concentrations of 220% w/w are used

for film-forming solutions to film-coat tablets. Lower-viscosity grades are used in aqueous film-

coating solutions, while higher-viscosity grades are used with organic solvents. Hypromellose at

concentrations between 0.451.0% w/w may be added as a thickening agent to vehicles for eye

drops and artificial tear solutions.

H.Description

Hypromellose is an odorless and tasteless, white or creamy-white fibrous or granular

powder.

I.Typical Properties

Acidity/alkalinity: pH = 5.58.0 for a 1% w/w aqueous solution.

Ash: 1.53.0%, depending upon the grade and viscosity.


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EXCIPIENTS PROFILE

Autoignition temperature: 360C

Density (bulk): 0.341 g/cm3

Density (tapped): 0.557 g/cm

3

Density (true): 1.326 g/cm3

Melting point: browns at 190200C; chars at 225230C.

Glass transition temperature is 170180C.

Moisture content:

Hypromellose absorbs moisture from the atmosphere; the amount of water absorbed

depends upon the initial moisture content and the temperature and relative humidity of the

surrounding air.

Solubility:

Soluble in cold water, forming a viscous colloidal solution; practically insoluble in

chloroform, ethanol (95%), and ether, but soluble in mixtures of ethanol and dichloromethane,

mixtures of methanol and dichloromethane, and mixtures of water and alcohol. Certain grades of

hypromellose are soluble in aqueous acetone solutions, mixtures of dichloromethane and propan-

2-ol, and other organic solvents.

Viscosity (dynamic):

A wide range of viscosity types are commercially available. Aqueous solutions are most

commonly prepared, although hypromellose may also be dissolved in aqueous alcohols such as

ethanol and propan-2-ol provided the alcohol content is less than 50% w/w.


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Typical viscosity values for 2% (w/v) aqueous solutions of Methocel (Dow Chemical

Co.). Viscosities measured at 20C.

Methocel product USP 28 designation Nominal viscosity (mPa s)

Methocel K100 Premium LVEP 2208 100

Methocel K4M Premium 2208 4000

Methocel K15M Premium 2208 15 000

Methocel K100M Premium 2208 100 000

Methocel E4M Premium 2910 4000

Methocel F50 Premium 2906 50

Methocel E10M Premium CR 2906 10 000

Methocel E3 Premium LV 2906 3





Metolose 60SH 2910 50, 4000, 10 000

Metolose 65SH 2906 50, 400, 1500, 4000

Metolose 90SH 2208 100, 400, 4000, 15000


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J.Stability and Storage Conditions

Hypromellose powder is a stable material, although it is hygroscopic after drying.

Solutions are stable at pH 311. Increasing temperature reduces the viscosity of solutions.

Hypromellose undergoes a reversible solgel transformation upon heating and cooling,

respectively. The gel point is 5090C, depending upon the grade and concentration of material.

K.Incompatibilities

Hypromellose is incompatible with some oxidizing agents. Since it is nonionic,

hypromellose will not complex with metallic salts to form insoluble precipitates.


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Ethyl cellulose:

Ethyl cellulose is a chain of -anhydro glucose units joined together by acetal linkage.

It is prepared from wood

.

pulp or chemical cotton by treatment with alkali and

ethylation of the alkali cellulose with ethyl chloride. Commercial ethyl cellulose has an

ethoxy content of 43-50 %. A 47 % product softens at 140oC and is soluble in ethyl acetate,

benzene, toluene, xylem and butanol.

The properties and pharmaceutical applications of ethyl cellulose are as follows:

Synonyms: Ethocel

Description: A tasteless, odourless free flowing, white to light tan powder.

Specific gravity: 1.14

Softening temperature: 152-1620

C

Emperical formula and Molecular weight:

Ethylcellulose with complete ethoxyl substitution (DS = 3) is C12H23O6 (C12H22O5)n

C12H23O5 where n can vary to provide a wide variety of molecular weights. Ethylcellulose, an

ethyl ether of cellulose, is a long-chain polymer of -anhydroglucose units joined together by

acetal linkages.

Structural formula:


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Functional Category:

Coating agent; flavoring fixative; tablet binder; tablet filler; viscosity-increasing agent.

Solubility:

Insoluble in water, glycerin, propylene glycol, but soluble in varying degrees in organic solvents.

Viscosity:

A property of ethyl cellulose such as tensile strength, elongation and flexibility

depends largely upon the degree of polymerization, which can be measured by viscosity.

Therefore, within each type-based ethoxyl content there exists low to high viscosity types,

based on degree of polymerization.

Stability:

It is resistant to alkali both dilute and concentrated but more sensitive to acidic

materials than cellulosic ethers.

Applications in pharmacy:

1. Binder in tablets:

Ethyl cellulose may be dry blended and wet granulated with a solvent such as alcohol.

Tablets made with ethyl cellulose as binder tent to exhibit poor dissolution and poor drug

absorption.

2.

Coating material for tablets:

Ethyl cellulose by itself forms a water insoluble film coating. It is commonly used

with Hydroxypropyl methylcellulose to alter the solubility of the film. Other materials

may be used for this as well.


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3. Coating material for stabilization:

Ethyl cellulose dissolved in i so propanol i s us ed t o co a t pa rt i c l es of dr u gs

t o form microcapsules. This type of microcapsules slows dissolution of the drug as

a function of microcapsule wall thickness.


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3. Xanthan Gum

A.Nonproprietary Names

BP: Xanthan gum

PhEur: Xanthani gummi

USPNF: Xanthan gum

B.Synonyms

Corn sugar gum; E415;Keltrol; polysaccharide B-1459;Rhodigel; Vanzan NF;Xantural.

C.Chemical Name and CAS Registry Number

Xanthan gum [11138-66-2]

D.Structural formula

E.Molecular Weight

Approximately 2000000.


Stabilizing agent; suspending agent; viscosity-increasing agent.


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G.Description

Xanthan gum occurs as a cream- or white-colored, odorless, free-flowing, fine powder.

H.

Typical Properties

Acidity/alkalinity: pH = 6.08.0 for a 1% w/v aqueous solution.

Freezing point: 0C for a 1% w/v aqueous solution.

Heat of combustion: 14.6 J/g (3.5 cal/g)

Melting point: chars at 270C.

Refractive index: n20

D = 1.333 for a 1% w/v aqueous solution.

Solubility:

Practically insoluble in ethanol and ether; soluble in cold or warm water.

Viscosity (dynamic):

12001600 mPa s (12001600 cP) for a 1% w/v aqueous solution at 25C.

I.Applications in Pharmaceutical Formulation or Technology

Xanthan gum is widely used in oral and topical pharmaceutical formulations, cosmetics,

and foods as a suspending and stabilizing agent. It is also used as a thickening and emulsifying

agent. It is nontoxic, compatible with most other pharmaceutical ingredients, and has good

stability and viscosity properties over a wide pH and temperature range. Xanthan gum gels show

pseudoplastic behavior, the shear thinning being directly proportional to the shear rate. The

viscosity returns to normal immediately on release ofshear stress. When xanthan gum is mixed

with certain inorganic suspending agents, such as magnesium aluminum silicate, or organic

gums, synergistic rheological effects occur.


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J.Stability and Storage Conditions

Xanthan gum is a stable material. Aqueous solutions are stable over a wide pH range (pH 312),

although they demonstrate maximum stability at pH 410 and temperatures of 1060C.

K.Incompatibilities

Xanthan gum is an anionic material and is not usually compatible with cationic

surfactants as precipitation occurs. Xanthan gum is compatible with most synthetic and natural

viscosity increasing agents.


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Cellulose, Microcrystalline: (Rowe R.C., et al., 2003)

A.Nonproprietary Names

BP: Microcrystalline cellulose JP: Microcrystalline cellulose

PhEur: Cellulosum microcristallinum USPNF: Microcrystalline cellulose

B.Synonyms

Avicel pH; Celex; cellulose gel; Celphere; Ceolus KG; crystalline cellulose; E460;

Emcocel; Ethispheres; Fibrocel; Pharmacel; Tabulose; Vivapur.

C.

Chemical Name and CAS Registry Number

Cellulose [9004-34-6]

D.Molecular Weight

36 000

E.Structural Formula


Adsorbent; suspending agent; tablet and capsule diluent; tablet disintegrant.

G.Description


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Microcrystalline cellulose is a purified, partially depolymerized cellulose that occurs as a

white, odorless, tasteless, crystalline powder composed of porous particles. It is commercially

available in different particle sizes and moisture grades that have different properties and

applications.

H.Typical Properties

Density (bulk): 0.337 g/cm3;

Density (tapped): 0.478 g/cm3;

Density (true): 1.5121.668 g/cm3

Flowability: 1.41 g/s

Melting point: chars at 260270C.

Specific surface area: 1.061.12 m2/g forAvicel PH-101;

1.211.30 m2/g forAvicel PH-102;

0.781.18 m2/g forAvicel PH-200.

1.211.30 m2/g forAvicel PH-102;

Moisture content:

Typically less than 5% w/w. However, different grades may contain varying amounts of

water. Microcrystalline cellulose is hygroscopic. (Avicel pH

- 102= 5.0)

Solubility:

Slightly soluble in 5% w/v sodium hydroxide solution; practically insoluble in water,

dilute acids, and most organic solvents.


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I.Applications in Pharmaceutical Formulation or Technology

Microcrystalline cellulose is widely used in pharmaceuticals, primarily as a

binder/diluent in oral tablet and capsule formulations where it is used in both wet-granulation

and direct compression processes. In addition to its use as a binder/diluent, microcrystalline

cellulose also has some lubricant and disintegrant properties that make it useful in tableting.

Uses of microcrystalline cellulose

Use Concentration (%)

Adsorbent 2090

Antiadherent 520

Capsule binder/diluent 2090

Tablet disintegrant 515

Tablet binder/diluent 2090

J.

Stability and Storage Conditions

Microcrystalline cellulose is a stable though hygroscopic material. The bulk material

should be stored in a well-closed container in a cool, dry place.

K.Incompatibilities

Microcrystalline cellulose is incompatible with strong oxidizing agents.


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TALC :

Synonyms: French chalk, purified talc, talcum, soapstone.

Description:

A very fine, white to grayish white, impalable, odorless crystalline powder,

unctuous, adheres readily to skin, soft to touch and free from granules.

Empirical formula: Mg6(Si2O5)4(OH)4.

Functional category:

USP: Tablet and/or capsule lubricant, glidant and anti caking agent

BP: Talc dusting powder

Others: Antiadherent

Typical Properties:

Density: 19-24 Ib/ft

Solubility: Insoluble in water, organic solvents, cold acids and dilute alkalis.

Stability and storage conditions:

Stable, Preserve in a well-closed container.

Incompatibilities:

Quaternary ammonium compounds.

Safety:

Talc dust exposure in the modern mining process does not appear to be

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