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Research Article CODEN: IJPRNK Impact Factor: 5.567 ISSN: 2277-8713 Singh Than, IJPRBS, 2019; Volume 8(4): 139-176 IJPRBS

Available Online at www.ijprbs.com 139

DEVELOPMENT AND EVALUATION OF LAMIVUDINE SUSTAINED RELEASE

MATRIX TABLETS

SINGH THAN*, ASIJA RAJESH, GOYAL ANIL KUMAR

Maharishi Arvind Institute of Pharmacy, Mansarovar, Jaipur, India-302020.

Accepted Date: 18/08/2019; Published Date: 27/08/2019

Abstract: Lamivudine is approved for clinical use and used widely in treatment of Hepatitis B and AIDS either alone or in combination with another antiviral drugs because of its water solubility and shorter half-life (5-7 hrs) drug requires frequent dosing by oral route, off various recent techniques for controlling drug release, matrix system offer various advantages of ease of formulation better control on release profile of drug and better patient compliance. The matrix tablets formulation by direct compression method is most acceptable in large scale production. It is concluded that formulation of sustained release tablet of Lamivudine containing 80 mg of hydroxypropyl-methylcellulose E15 (high viscosity grade) and 80 mg of ethylcellulose i.e. formulation F7 can be taken as an ideal or optimized formulation of sustained release tablets for 16 hours release as it fulfills all the requirements for sustained release tablet and our study encourages for the further clinical trials and long term stability study on this formulation.

Keywords: Sustained Release, Lamivudine, Matrix Tablet, Hepatitis B

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INTRODUCTION

Hepatitis B is a extreme disease due to a pandemic that attacks the liver. The virus that is

known as Hepatitis B virus (HBV) can cause lifelong infection, cirrhosis (scarring) of the liver,

liver most cancers, liver failure, and loss of life.

Lamivudine, one of the dideoxycytidne (ddC) analogue NRTIs, is the primary nucleoside

analogue accredited to treat persistent HBV contamination and has been shown to gain diverse

classes of patients. These encompass H Be-nice N and -poor sufferers, nonresponders to

interferon- remedy, and patients with Decompensate cirrhosis.

The successful remedy of Hepatitis B relies upon on the maintenance of powerful drug

concentration level in the body for which a steady and uniform supply of drug is desired.

Sustained release dosage forms deliver the drug at a sluggish release rate over an extended

time period and gain this objective. To lessen the frequency of management and to improve

patient compliance, a once-each day sustained launch method of Lamivudine is acceptable.

Matrix drugs composed of drug and release retarding cloth (e.g. Polymer) provide the best

technique in designing a sustained launch machine. Matrix drugs of Lamivudine are organized

by way of direct compression technique the use of polymers HPMC and Ethyl cellulose. Matrix

dosage shape can remain the intestinal place for numerous hours and as a result considerably

extend the intestinal residence time of the drugs. Prolonged transit time improve

bioavailability.

Hepatitis B

The scientific term “hepatitis” actually way “irritation of the liver”. Chronic irritation of the liver

may also bring about liver damage or failure if left untreated. “Hepatitis” can be resulting from

many different things - ingesting an excessive amount of alcohol, annoying harm, autoimmune

problems, an destructive drug response, or a plague together with the hepatitis B virus.

Hepatitis B is a critical disease because of a deadly disease that assaults the liver. The virus,

that's referred to as hepatitis B virus (HBV), can reason lifelong infection, cirrhosis (scarring) of

the liver, liver most cancers, liver failure, and death. Chronic Hepatitis B. The development from

acute to persistent contamination is essentially have an impact on by means of the age of the

person that becomes in touch with the virus. The chronic segment of the sickness is decide

while someone’ immune system isn't always capable of clear the virus six months later after

preliminary exposure to HBV.

Signs and Symptoms: Abou fght 30% of persons don't have any signs and symptoms or signs.

Signs and symptoms are much less common in kids than adults. The following signs and



symptoms had been observed like- Jaundice, Fatigue, Abdominal ache, Loss of appetite,

Nausea, vomiting, and Joint pain.

Cause and Transmission: Hepatitis B virus (HBV) is located in blood and certain frame fluids. The

virus is unfold while blood or frame fluid from an infected character enters the body of

someone who isn't always immune.

HBV is spread thru having unprotected sex with an infected character, sharing needles or

works. When shooting pills, publicity to needle sticks or sharps on the activity, or from an

infected mom to her baby all through start. Exposure to inflamed blood in any state of affairs

can be a danger for transmission. HBV is a small, partly double-stranded DNA virus and a

prototype member of the hepadna virus own family. Its 3.2 kb genome possesses 4 overlapping

open analyzing frames encoding the envelope (pre-S/S), canter (precore/core), polymerase and

X proteins. Among those hepadnavirus proteins, an unmarried protein contains the enzyme

catalyzing RNA- and DNA based DNA polymerase, RNase H and protein priming sports [1-3]

Sustained Release Dosage Form:

In this type of dosage forms, a sufficient amount of drug is initially made available to the body

to cause a desired pharmacological response. The remaining fraction is released periodically

and is required to maintain the maximum initial pharmacological activity for some desirable

period of time in excess of time expected from usual single dose. [4-6]

Matrix Tablet: One of the least complex techniques to the manufacture of sustained release

dosage bureaucracy entails the direct compression of blends of drug, retardant fabric, and

additives to shape a tablet in which drug is embedded in a matrix centre of retardant

Mechanism of Action of Lamivudine: Lamivudine is a synthetic nucleoside analogue.

Intracellularly, lamivudine is phosphorylated to its active 5′-triphosphate metabolite,

lamivudine triphosphate, 3TC-TP. Incorporation of the monophosphate form into viral DNA by

HBV reverse transcriptase results in DNA chain termination. 3TC-TP also inhibits the RNAand

DNA-dependent DNA polymerase activities of HIV-1 reverse transcriptase (RT). 3TC-TP is a weak

inhibitor of mammalian α, β, and gamma-DNA polymerases [7-10].

MATERIALS AND METHODS

Materials:

Lamivudine USP, Lactose monohydrate BP, Hydroxypropyl Methylcellulose E-15 BP, Ethyl

cellulose BP, Magnesium Stearate BP, Colloidal Silicon dioxide (Aerosil® -200) USPNF, Acetone



BP, Sodium hydroxide BP, Glacial acetic acid BP, Potassium dihydrogen Phosphate BP,

Demineralized water, Methanol BP, Salicylic acid BP, Ammonium acetate BP.

Method:

Preformulation Studies [11-14]

To develop an intelligent formulation - preformulation stability studies are usually the first

quantitative assessment of chemical stability of a drug as well as stability in presence of other

excipients for a formulation. “A case of learning before doing”

The following preformulation studies were performed:

A. Melting point of drug

B. Effect of temperature and humidity in open & closed vial conditions

C. Solubility analysis

D. Powder characterization

Melting Point of Drug:

The melting point of Lamivudine was determined by capillary method, using definite quantity of

Lamivudine taken and placed in apparatus and determined the melting point and matched with

the standards given in USPNF.

Effect of Temperature and Humidity in Open & Closed Vial Conditions:

Method: The drug and individual excipient and mixture of all excipient and drug were taken in

ration of 1:1 in a flint vial and stored at 25°C, 60%, 30°C, 65% RH and 40°C, 75% RH for 4 weeks.

The samples were observed for any physical change every week. The two method employed are

open vial and closed vial. In closed vial method after placing the material the vial is sealed while

in open vial the vial is not closed and placed for the study.

Solubility Analysis:

Solubility is an important parameter for preformulation studies because:

a. It affects the dissolution of drug

b. Bioavailabity of drug is directly affected by dissolution and absorption of drug by oral

administration.



c. Particle size, shape, surface area may affects the dissolution characteristics of drug hence it

should be determined during preformulation.

Method: Appropriate quantity of drug was weighed and added to the suitable volume of

solvent.

Powder Characterization:

Angle of repose:

The angle of repose is the maximum angle of a stable slope determined by friction, cohesion

and the shapes of the particles. When bulk granular materials are poured onto a horizontal

surface, a conical pile will form. The internal angle between the surface of the pile and the

horizontal surface is known as the angle of repose and is related to the density, surface area,

and coefficient of friction of the material. Material with a low angle of repose forms flatter piles

than material with a high angle of repose. In other words, the angle of repose is the angle a pile

forms with the ground.

Figure 1: Demonstration of Angle of repose

Angle of repose was determined using funnel method. The height of the funnel was adjusted in

such a way that the tip of the funnel just touches the heap of the blends. Accurately weighed

blend is allowed to pass through the funnel freely on to the surface. The height and diameter of

the powder cone was measured and angle of repose was calculated using the following

equation.

= tan-1 (h/r)

Where, h = Height of pile, r = Radius of pile, and = Angle of repose

Table 1: Flow property & angle of repose

Flow property Angle of Repose (Degrees)

Excellent 25-30

Good 31-35



Fair – aid not needed 36-40

Passable – may hang up 41-45

Poor – must agitate, vibrate 46-55

Bulk Density and Tapped Density

It is the ratio between a given mass of a powder and its bulk volume

Bulk Density = Mass of powder / Bulk Volume of the powder

A given quantity of powder (2 gm) is transferred to a measuring cylinder (10 ml) and is tapped

mechanically till a constant volume is obtained. This volume is the bulk volume and it includes

true volume of the powder and the void space among the powder particles. Tapped density is

calculated by using the formula

Tapped density = Weight of powder / Tapped volume of the powder

Carr’s Index

Carr’s compressibility index CI (Carr, 1965) is defined as follows:

CI = rt - ra / rt = Va – Vt / Vt

Where rt and ra – tapped and poured bulk density; And Vt and Va – tapped and poured bulk

volume respectively.

A simple indication of the ease with which a material can be induced to flow is given by

application of a compressibility index (I), is also given by the equation

I= [1- Tapped density / Bulk density] x 100.

Values of I below 15% usually give rise to good flow characteristics, but readings above 25%

indicate poor flow ability.

Hausner’s Ratio

A similar index has been defined by Hausner.

Hausner’s ratio = Tapped density / Poured Density

Or H = rt / ra = Va / Vt



Carr’s index and Hausner’s ratio are equivalent measures and hence only one usually Carr’s

index measured.

Table 2: Relation between Flow property and Carr’s index & Hausner’s Ratio

Carr’s index Flow Character Hausner’s Ratio

< 10 Excellent 1.00-1.11

< 11-15 Good 1.12-1.18

16-20 Fair 1.19-1.25

21-25 Passable 1.26-1.34

26-31 Poor 1.35-1.45

32-37 Very poor 1.46-1.59

>38 Very, very poor >1.60

Formulation Development of Lamivudine Sustained release matrix tablets [15-16]

Considerations of Formulation Development:

A. Direct Compression for polymers were selected according to literature

B. Use of HPMC and Ethyl cellulose in different ratios

C. Drug dose was calculated on pharmacokinetic data

D. All excipients were selected according to standard references

Dose Calculation (Theoretical Release Profile):

Total dose of Lamivudine for once daily sustained release formulation was calculated by the

following equation using available pharmacokinetic data.

Dt = Dose (1 + 0.639 × t / t½)

Where, Dt is total dose of drug; Dose of immediate release part (100); t is time in hours during

which the sustained release is desired; t½ is half life of the drug (5-7 hours)

Dt = 30 (1 + 0.639 × 24 / 6)



= 106.68 mg

Hence, the formulation should release 30 mg in first couple of hour like conventional tablets,

and remaining amount completely in 24 hrs.

Formulation of Lamivudine Sustained Release Matrix Tablets:

Table 3: Quantity of Raw Materials per Tablet (In mg)

Sr.

No.

Ingredient F1 F2 F3 F4 F5 F6 F7 F8

1. Lamivudine USP 100 100 100 100 100 100 100 100

2. Lactose

monohydrate

132 132 132 132 132 132 132 132

3. Hydroxypropyl

Methylcellulose E-

15

30 35 40 50 60 70 80 90

4. Ethyl cellulose 130 125 120 110 100 90 80 70

5. Colloidal Silicon

Dioxide (Aerosil®)

4 4 4 4 4 4 4 4

6 Magnesium

Stearate

4 4 4 4 4 4 4 4

*Total weight of per unit tablet is 400 mg.

Formulation Procedure (Direct Compression Method):

All ingredients was collected and weighed accurately. Sifted Lamivudine USP with lactose and

polymers through sieve no. 60# and then rinsed with remaining excipients. Sifted colloidal

silicon dioxide (Aerosil-200) and magnesium stearate separately, through sieve no.60#. Pre

blending of all ingredients (except lubricant-magnesium stearate) in blended for 15 minutes.

Blend then again blended for 5-6 min. then added magnesium stearate blended 5 min.

Lubricated powder was compressed by using 9 station single rotary machine having 9.5 mm

diameter – circular concave shaped and one side break line on upper punch, with pressure of 7-

8 tons. Compressed tablets were examined as per official standards and unofficial tests

(discussed below). Tablets were packaged in well closed light resistance and moisture proof

containers.



Manufacturing Process Flow Diagram:

Evaluation [17-20]

Evaluation of Lubricated Blends:

Lubricated blends of all formulations was examined and determined Angle of repose, Bulk

density, tapped density, Carr’s index and Hausner ’s ratio as procedure given in preformulation

section i.e. in powder flow characteristics. All observations are given in results and discussion

part.

Evaluation of Tablets:

Tablet Description

General appearance of tablet involves the measurement of a number of attributes such as a

tablet’s size, shape, color, presence or absence of an odor, taste, surface texture, physical flaws

and consistency, and legibility of any identify markings.



Uniformity of weight

The USP weight variation test was carried out by weighing 20 tablets individually, calculating

the average weight, comparing the individual tablet weight to average weight. The tablet meet

USP test if no tablet differs by more than two times of percentage deviation.

Table 4: USP Standards for Weight Variation Test

Average weight of Tablets Max. percentage deviation

130 or less 10

130 – 324 7.5

324 mg or more 5

Thickness and Diameter

Thickness and diameter of 5 tablets is measured by using vernier caliper.

Mechanical Strength

Crushing Strength: Hardness of tablet is defined as the force applied across the diameter of the

tablet in order to break the tablet. The resistance of the tablet to chipping, abrasion or

breakage under the condition of storage, transportation and handling before usage depends in

its hardness. Hardness of tablets of each formulation was determined using Pfizer hardness

tester. Hardness of 10 tablets of each formulation was evaluated by Pfizer hardness tester.

Abrasion: Friability test is a measure of mechanical strength of tablets. The test was performed

by using Electro lab friabilator test apparatus.

The pre weighed tablets were placed in the friabilator. Friabilator consists of a plastic chamber

that revolves at 25 rpm, dropping the tablets at a distance of 6 inches in each revolution. The

tablets were rotated in friabilator for 4 minutes. At the end of test, tablets were reweighed. The

% weight loss in weight of tablet is the measure of friability and is expressed in B as,

B = 100 [1 – W / W 0]

Where, W is initial weight and W0 is final weight after abrasion.

E. Assay

Determined by Liquid Chromatography.

Test solution: Dissolve 25 mg of the substance under examination in 100 ml of mobile phase.



Reference solution: A 0.025 per cent w/v solution of lamivudine RS in mobile phase.

Chromatographic system:

A stainless column 15 cm & 4.6 mm, packed with octa-adecylsilane chemically bonded to

porous silica (5 mm)

Temperature column 35°C,

Mobile phase: a degassed mixture of 5 volumes of methanol and 95 volumes of buffer

prepared by dissolving 1.9 g of ammonium acetate in 1000 ml of water and adjusting the pH to

3.8 ± 0.2 with glacial acetic acid,

Flow rate- 1 ml per minute,

Spectrophotometer set at 270 nm,

A 20 ml loop injector.

Injected the reference solution. The test is not valid unless the column efficiency determined

from the lamivudine peak is not less than 5000 theoretical plates, the tailing factor is not more

than 2.0 and the relative standard deviation for replicate injections is not more than 2.0

percent. Injected alternatively the test solution and the reference solution. Calculated the

content of C8H11N3O3S. The percent labelled amount was calculated by:

Where At is mean area of standard, As is mean area of Sample, P is % purity of standard, T is

theoretical average weight, and L is label claim.

In-vitro dissolution study [16, 21]:

Apparatus - USP Basket type

Speed - 100 rpm

Media - 6.8 pH buffer solution

Volume of media - 900 mL

Temperature - 37 ±0.5 °C

Sampling Intervals - 1, 2, 4, 8, 12, and 16 hours



Preparation of Standard Curve [22-24]

A. Preparation of 6.8 pH phosphate buffer:

Placed 50 mL of the monobasic potassium phosphate solution in a 200 mL volumetric flask,

added 22.4 mL of 0.2 M sodium hydroxide, then added water to volume.

B. Preparation of standard curve of Lamivudine in 6.8 pH phosphate buffer:

Accurately weighed 100 mg of Lamivudine was dissolved in 100 ml of phosphate buffer (6.8 pH)

which gives the concentration of 1000mg/ml. 1ml of this solution was taken and made upto

100ml with buffer solution which contains the concentration of 10 mg/ml, 1 to 10ml were taken

from this solution and made upto 10ml to get the concentration ranges of 1 to 10mg/ml. The

absorbance of the resulting solutions was then measured at 265nm using U.V.

spectrophotometer, against respective parent solvent as a blank.

The standard curve was obtained by plotting absorbance V/s. concentration in mcg/ml and data

was subjected to weighed linear regression analysis in Microsoft excel.

Dissolution Study [16, 25]:

Placed the 900 ml of pH 6.8 phosphate buffer in the vessel of apparatus and assembled,

equilibrate the dissolution medium to 37 ±0.5 °C. P laced 1 tablet in basket and immediately

operated the apparatus at 100 rpm. Withdrawn the 5 ml samples at 1 hour, 2 hours, 4 hours, 8

hours, 12 hours, and 16 hours, from midway between the surface of dissolution medium and

the top of the rotating basket, not less than 1 cm from the vessel wall and replaced with fresh

buffer solution. After appropriate dilution the samples were analyzed. Cumulative percentage

of the drug released was calculated, and the mean of 6 tablets from formulations was used in

data analysis.

Kinetic Modelling:

The in vitro and in vivo data were analyzed by the zero order kinetics equation as well as

Higuchi’s and Korsmeyer-Peppa’s equation to understand the release profile and release

mechanism. When a graph of the cumulative percentage of the drug released from the matrix

against time is plotted, zero order release is linear in such a plot, indicating that the release rate

is independent of concentration. The rate of release of the drug can be described

mathematically as follows:

Rate of release = (dCs/t) = k



Where Cs = concentration of the drug present in the matrix, k = rate constant and t = time. Since

Cs is a constant, and x = amount of drug released described as

dx/dt = k integration of the equation yields x = kt + constant.

A plot of x versus t results in a straight line with the slope = k. The value of k indicates the

amount of the drug released per unit of time and the intercept of the line at time zero is equal

to the constant in the equation. The curves plotted may have different slopes, and hence it

becomes difficult to exactly pin-point which curve follows perfect zero order release kinetics.

Therefore, to confirm the kinetics of drug release, data were also analyzed using Korsemeyer’s

equation. Korsemeyer u sed a simple empirical equation to describe general solute release

behavior from controlled release polymer matrices:

Mt/M = atn

Where Mt/M = fraction of drug released, a = kinetic constant, t = release time and n = the

diffusional exponent for drug release.

The slope of the linear curve gives the ‘n’ value. Peppas stated that the above equation could

adequately describe the release of solutes from slabs, spheres, cylinders and discs, regardless of

the release mechanism. The value of ‘n’ gives an indication of the release mechanism. When n =

1, the release rate is independent of time (zero order) (case II transport); n = 0.5 for Fickian

diffusion; and when 0.5 < n < 1, diffusion and non-Fickian transport are implicated. Lastly, when

n > 1.0 super case II transport is apparent. ‘n’ is the slope value of log Mt/ M versus log time

curve.

The different models, viz.-zero-order, Higuchi’s equation and Korsmeyer-Peppa’s equation were

used to study the in vitro release of the sustained release matrix tablets. The zero order plots of

formulations were found to be fairly linear as indicated by their high regression values.

Therefore, it was ascertained that the drug release from modified ocular inserts followed either

near zero or zero order kinetics. The zero order curves alone are not sufficient to predict zero

order since each curve, albeit straight, has a different slope. Hence to confirm the exact

mechanism of drug release from the films, the datas were computed and graphed according to

Higuchi’s equation and Korsemeyer’s Peppa’s equation.

Comparison of F-7 and Marketed Tablets:

Physical parameters:

Were compared physical parameters of the marketed product (EPIVIR HBV Tablets) and best

formulation F-7 Lamivudine matrix tablets as like thickness, hardness, and appearance.



Contents uniformity of active ingredients:

Determined by HPLC method is also given in assay part.

Cumulative percentage drug release profile:

Compared the best formulation F-7 and marketed product (Epivir HBV Tablets) dissolution

profile were calculated as cumulative release profile and plotting the graph Cumulative % drug

release vs. time (hours).

Accelerated Stability Study of Formulation (F7) [26-28]

The purpose of stability testing is to assess the effect of temperature, humidity, light and other

environmental factor on the quality of drug substance or product. The results are used to

establish storage condition, retest period, shelf life and to justify overages included in product

for stability reason.

Optimized formulation (F7) was kept for stability testing for three month at 25°C + 2°C, 60%RH,

30°C + 2ºC, 65% and 40°C + 2ºC, 75% RH. Every month tablet were tested for its dissolution

study. It shows the near about same result in refrigerated and room temperature which shows

tablet will be stable in both in refrigerated and room temperature.

RESULTS AND DISCUSSION

Result of preformulation study of drug

Melting Point of Drug:

The melting point of Lamivudine was determined by capillary method, melting point of

Lamivudine was found to be 178°C to 182°C while reported melting point is 177.5°C-183°C.

Melting point compared with USP standards that are found to be within limits.

Effect of Temperature and Humidity in Open & Closed Vial Conditions:

The drug–excipients compatibility was done at 25ºC/60% + 5%,30ºC / 65% + 5% relative and

40ºC/75% + 5% relative humidity. Opened and closed vial methods were used. The result

doesn’t show any physical change to the mixture after 4 weeks. chemical compatibility were

analyzed by spectrum study. This fact concluded that the drug and excipients are compatible

with each other.



Table 5: Preformulation study in closed vial condition

Drug Observation

1:1 Excipient Initial 25ºC /60% RH after 30 days

30ºC /65% RH after 30 days

40ºC /75% RH after 30days

Result

Lamivudine White to off white

White to off white

White to off white

White to off white

Compatible

Lamivudine + Ethyl cellulose

White White White White Compatible

Lamivudine + HPMC K15M


Lamivudine + all excipients 1:1


Table 6: Preformulation study in open vial condition

Drug Observation

1:1 Excipient Initial 25ºC /60% RH after 30 days

30ºC /65% RH after 30 days

40ºC /75% RH after 30days

Result

Lamivudine White to off white

White to off white

White to off white

White to off white

Compatible

Lamivudine + Ethylcellulose


Lamivudine + HPMC K15M


Lamivudine + all excipients 1:1


Solubility Analysis

Lamivudine samples are examined and it was found to be soluble in water and methanol.

Powder Characterization



Table 7: Powder Characterization

Sample Bulk density g/cm3

Tap density g/cm3

Carr’s index Hausner’s ratio

Angle of repose

Lamivudine 0.78 + 0.18 0.96 + 0.13 18.73 + 0.11 1.23 + 0.18 17°

HPMC E 15 0.39 + 0.29 0.53 + 0.33 26.16 + 0.33 1.36 + 0.20 26°

EC 0.40 + 0.30 0.52 + 0.11 23.07 + 0.28 1.30 + 0.21 29°

*Values shown in tables are mean of three determinations.

Evaluation

Evaluation of Lubricated Blends

Control of amount: The initial batches were of directly compression method which needs

higher amount of excipient to reduce the friability and improve hardness indirectly which

affects the release of drug from polymer. The total weight 400 mg was used successfully to

meet all criteria.

Selection of batches: The study was well targeted for SR release of Lamivudine all the criteria of

drug was properly studied along with polymer property the amount of drug with polymer was

of great importance the initial failed batches of polymer with drug were properly performed

and studied.

Table 8: Evaluation of lubricated blends

Parameters F-1 F-2 F-3 F-4 F-5 F-6 F-7 F-8

Mean Angle of repose* ± S.D.

33˚43’ ±0.309

31˚77’ ±0.284

34˚42’ ±0.280

36˚09’ ±0.257

33˚66’ ±0.241

31˚00’ ±0.216

32˚37’ ±0.226

31˚95’ ±0.402

Mean Apparent bulk density * (g/cm3) ± S.D

0.593 ±0.002

0.622 ±0.003

0.597 ±0.004

0.629 ±0.003

0.616 ±0.002

0.676 ±0.003

0.603 ±0.003

0.578 ±0.002

Mean Tapped bulk density* (g/cm3) ± S.D.

0.704 ±0.003

0.688 ±0.002

0.739 ±0.003

0.720 ±0.002

0.666 ±0.003

0.696 ±0.002

0.656 ±0.003

0.701 ±0.003

Compressibility Index* (%)

17.040 17.983 16.576 15.282 18.607 17.667 19.339 19.403



Hausner’s Ratio*

1.190 ± 0.096

1.183 ±0.14

1.165 ±0.070

1.147 ±0.18

1.129 ±0.025

1.206 ±0.035

1.176 ±0.16

1.166 ±0.066

*Values shown in tables are mean of three determinations.

Evaluation of Tablets

Tablet Description:

The tablets descriptions found White, round biconvex, with break line in one side, uncoated

tablets.

Figure 2: Photograph of Tablet

Tablet Diameter and Thickness:

The tablet dimension includes diameter and thickness of tablets. The diameter was found to be

9.51 to 9.53 mm.

Thickness of all formulations was found between 4.917 to 4.943. No significant difference was

observed in the thickness of individual tablet from the average value.

Weight variation:

No significant difference was observed in the weight of individual tablets form the average

weight. Tablet weights of all bathes were found within recommended USP limits, between 400

± 8 mg.

Mechanical strength

Crushing strength (Hardness) of tablets of all batches are in between 11 ± 0.05 to 11 ± 0.74

(Kg/cm2) which is acceptable limits, which shows in the literature.



Abrasion (Friability) of all the formulation showed % friability less than 1% that indicates ability

of tablets to withstand shocks, which may encountered.

Table 9: Observations of All Tablets Evaluation Parameters

Parameters F-1 F-2 F-3 F-4 F-5 F-6 F-7 F-8

Uniformity of weight (mg)*

400 ± 6

400 ± 8

400 ± 7

400 ± 5

400 ± 7

400 ± 6

400 ± 6

400 ± 5

Thickness (mm)*

4.9 ± 0.26

4.9 ± 0.17

4.9 ± 0.33

4.9 ± 0.20

4.9 ± 0.43

4.9 ± 0.39

4.9 ± 0.26

4.9 ± 0.30

Diameter (mm)* 9.5 ± 0.02

9.5 ± 0.03

9.5 ± 0.02

9.5 ± 0.01

9.5 ± 0.03

9.5 ± 0.01

9.5 ± 0.01

9.5 ± 0.02

Friability (%)* 0.06 0.11 0.19 0.14 0.16 0.11 0.09 0.07

Tablet Hardness (Kp)*

11 ± 0.08

11 ± 0.05

11 ± 0.06

11 ± 0.09

11 ± 0.10

11 ± 0.14

11 ± 0.74

12 ± 0.09

Assay (%) 97.88 98.63 98.12 97.34 97.68 97.24 98.76 98.44

Assay

The data of uniformity of content which was performed by HPLC, indicated that tablets of all

batches had drug content within USP limits. i.e. between 97.34 to 98.76 %.



HPLC Chromatogram of Formulation-7:

Figure 3: HPLC Graph of formulation-7

In guidance of industrial scientist different parameter of tablet like flow property, dimension

hardness, drug content etc. were studied which results in successful trials.

In Vitro Dissolution Study:

Standard Curve of Lamivudine in pH 6.8 phosphate buffer:

Standard calibration curve of Lamivudine were prepared in phosphate buffer of 6.8 pH.

Correlation coefficient value (0.998648) indicates that there is a linear correlation between

concentration and absorbance.



Table 10: Standard calibration curve concentration and absorbance

Sr. No. Concentration in mcg/ml

Absorbance at 270 nm

1 1 0.027

2 2 0.051

3 3 0.089

4 4 0.105

5 5 0.136

6 6 0.159

7 7 0.179

8 8 0.202

9 9 0.231

10 10 0.254

*Average of three determinations

Figure 4: Standard Calibration Curve of Lamivudine

Slope: 0.025209

Regression Coefficient: 0.998648



Table 11: In Vitro Drug Release Study for Formulation-1

Time in Hours

Sq. rt. Of Time

Log Time


Concentration in

Amount in 900 ml

% drug release

Cumulative % drug release

Log cumulative% drug release

0 0 0 0 0 0 0 0 0

1 1 0 0.036 1.440 12.960 12.960

12.961 1.113

2 1.414

0.301

0.066 2.624 23.620 23.620

23.623 1.373

4 2 0.602

0.115 4.556 41 41 41.005 1.613

8 2.828

0.903

0.162 6.410 57.690 57.690

57.696 1.761

12 3.464

1.079

0.180 7.137 64.230 64.230

64.237 1.808

16 4 1.204

0.199 7.896 71.060 71.060

71.068 1.852


Figure 5: In Vitro Drug Release of F1



Figure 6: Higuchi's Plot for F1

Figure 7: Peppa's Plot for F1


Time in Hours

Sq. rt. Of Time

Log Time


Concentratio

n in g/ml

Amount in 900 ml

% drug release



0 0 0 0 0 0 0 0 0

1 1 0 0.038 1.490 13.410 13.410

13.411 1.127

2 1.414

0.301

0.082 3.234 29.110 29.110

29.113 1.464

4 2 0.602

0.145 5.739 51.650 51.650

51.656 1.713

8 2.828

0.903

0.191 7.582 68.240 68.240

68.248 1.834

12 3.46 1.07 0.219 8.697 78.270 78.27 78.279 1.894



4 9 0

16 4.000

1.204

0.232 9.187 82.680 82.680

82.689 1.917








Time in Hours

Sq. rt. Of Time

Log Time


Concentratio

n in g/ml

Amount in 900 ml

% drug release



0 0 0 0 0 0 0 0 0

1 1 0 0.048 1.907 17.160 17.160

17.162 1.235

2 1.414

0.301

0.094 3.737 33.630 33.630

33.634 1.527

4 2 0.602

0.157 6.236 56.120 56.120

56.126 1.749

8 2.828

0.903

0.199 7.914 71.230 71.230

71.238 1.853

12 3.464

1.079

0.227 9.017 81.150 81.150

81.159 1.909

16 4 1.204

0.248 9.847 88.620 88.620

88.630 1.948








Time in Hours

Sq. rt. Of Time

Log Time


Concentratio

n in g/ml

Amount in 900 ml

% drug release



0 0 0 0 0 0 0 0 0

1 1 0 0.061 2.409 21.680 21.680

21.682 1.336

2 1.414

0.301

0.107 4.238 38.140 38.140

38.144 1.581

4 2 0.602

0.171 6.799 61.190 61.190

61.197 1.787

8 2.828

0.903

0.214 8.504 76.540 76.540

76.549 1.884



12 3.464

1.079

0.236 9.359 84.230 84.230

84.239 1.926

16 4 1.204

0.250 9.919 89.270 89.270

89.280 1.951








Time in Hours

Sq. rt. Of Time

Log Time


Concentratio

n in g/ml

Amount in 900 ml

% drug release



0 0 0 0 0 0 0 0 0

1 1 0 0.072 2.846 25.610 25.610

25.613 1.408

2 1.414

0.301

0.115 4.574 41.170 41.170

41.175 1.615

4 2 0.602

0.183 7.279 65.510 65.510

65.517 1.816

8 2.828

0.903

0.219 8.696 78.260 78.260

78.269 1.894

12 3.464

1.079

0.247 9.796 88.160 88.160

88.170 1.945

16 4 1.204

0.252 10.013 90.120 90.120

90.130 1.955








Time in Hours

Sq. rt. Of Time

Log Time


Concentration in

Amount in 900 ml

% drug release



0 0 0 0 0 0 0 0 0

1 1 0 0.073 2.91 26.190 26.190

26.193 1.418

2 1.414

0.301

0.126 4.993 44.940 44.940

44.945 1.653

4 2 0.602

0.188 7.474 67.270 67.270

67.277 1.828

8 2.828

0.903

0.222 8.798 79.180 79.180

79.189 1.899

12 3.464

1.079

0.251 9.947 89.520 89.520

89.530 1.952

16 4 1.204

0.266 10.542 94.880 94.880

94.891 1.977










Time in Hours

Sq. rt. Of Time

Log Time


Concentration in

Amount in 900 ml

% drug release



0 0 0 0 0 0 0 0 0

1 1 0 0.080 3.161 28.450 28.450

28.453 1.454

2 1.414

0.301

0.131 5.186 46.670 46.670

46.675 1.669

4 2 0.602

0.193 7.641 68.770 68.770

68.778 1.837

8 2.828

0.903

0.227 9.026 81.230 81.230

81.239 1.910

12 3.464

1.079

0.254 10.063 90.570 90.570

90.580 1.957

16 4 1.204

0.277 10.988 98.890 98.890

98.901 1.995

*Average of three determination







Time in Hours

Sq. rt. Of Time

Log Time


Concentration in

Amount in 900 ml

% drug release



0 0 0 0 0 0 0 0 0

1 1 0 0.076 3.019 27.170 27.170

27.173 1.434

2 1.414

0.301

0.118 4.697 42.270 42.270

42.275 1.626

4 2 0.602

0.183 7.248 65.230 65.230

65.237 1.814

8 2.828

0.903

0.222 8.799 79.190 79.190

79.199 1.899

12 3.464

1.079

0.252 9.998 89.980 89.980

89.990 1.954

16 4 1.20 0.273 10.852 97.670 97.67 97.681 1.990



4 0







Idea after dissolution study: The amount released in fixed duration was of more importance

and were performed with precision and accuracy, the change in amount of polymer was largely

dependent on the hydrophobic and hydrophilic nature of polymers used in the dissolution

study and it suggested many parameter to control for next batches.

The release of Lamivudine from sustained release tablet of various formations varied according

to the amount and hydrophilic and hydrophobic nature of polymer. As the amount of ethyl

cellulose was decreased and amount of HPMC was increased there is increase in release rate in

the order F1 to F7, probably the reason for this was hydrophilic nature of HPMC and

hydrophobic nature of ethyl cellulose. The formulation F7 was found to give best release rate

with 98.901 (Cumulative % drug release).

F. Kinetic Modelling:

The different models, viz.-zero-order, Higuchi’s equation and Korsmeyer-Peppas equation were

used to study the in vitro release of matrix tablets. The zero order plots of formulations were

found to be fairly linear as indicated by their high regression values. Therefore, it was

ascertained that the drug release from matrix tablets followed either near zero or zero order

kinetics. The zero order curves alone are not sufficient to predict zero order since each curve,

albeit straight, has a different slope. Hence to confirm the exact mechanism of drug release

from the films, the data’s were computed and graphed according to Higuchi’s equation and

Korsemeyer’s Peppa’s equation. Regression values of Higuchi’s plot revealed that the

mechanism of drug release was diffusion. The in-vitro kinetic data is subjected to log time-log

drug release transformation plot (Korsmeyer-Peppas plot),all the slope values ranges from

1.020803 to 1.116491(n>1) revealed the fact that the drug release follows super case II

transport diffusion, possibly owing to chain distanglement and swelling of hydrophilic polymer.

Regression values of Higuchi’s plot revealed that the mechanism of drug release was dissolution

and diffusion. The in-vitro kinetic data is subjected to log time-log drug release transformation

plot (Korsmeyer-Peppas plot), all the slope values ranges from 1.020803 to 1.116491. (n>1)

revealed the fact that the drug release follows super case II transport diffusion, possibly owing

to chain distanglement and swelling of hydrophilic and hydrophobic polymer.

Table 19: In-Vitro Drug Release Kinetic Data

Formulation Code

Zero order Higuchi’s Peppa’s

Slope Regression Slope Regression Slope Regression

F1 4.21780 0.93927 18.99421 0.99014 1.06699 0.81223

F2 4.98077 0.92686 22.59234 0.98413 1.11649 0.81076

F3 5.13193 0.92506 23.39370 0.98709 1.08484 0.78347

F4 5.04823 0.90158 23.45237 0.98045 1.04857 0.75297



F5 5.01458 0.88668 23.56630 0.97542 1.02466 0.73177

F6 5.16955 0.89104 24.24039 0.97804 1.02635 0.72778

F7 5.29398 0.89397 24.79492 0.98011 1.02080 0.72015

F8 5.35343 0.90911 24.81010 0.98625 1.03096 0.73149

Comparison of Formulation-7 and Marketed Tablets

The formulations obtained in evaluation studies were compared with marketed product (Epivir

HBV Tablets). The evaluation parameters tested and compared were physical and analytical

parameters. The Physical parameter values obtained are recorded in results and discussion

part. The Analytical parameters formulation F-7 and marketed product (Epivir HBV Tablets)

gave Table 21 and Table 22 of formulation is constructed graphically. The graphical comparison

is shown in Figure 29. The above study has shown that the contents of drug, In-Vitro drug

release profile and physical parameters of F-7 formulations were found to be better as

compared with that of marketed product of Lamivudine (Epivir HBV Tablets).

Table 20: Content Uniformity of Active Ingredients

Parameters F-7* Lamivir HBV Tablets*

Contents uniformity of Drug (%)

100.05% ± 0.66 101.09% ± 0.78


Table 21: Physical Characteristics

Parameters Formulation F-7 Epivir HBV Tablets

Appearance Biconvex round shape Capsule shaped

Colour White Light Brown

weight ± SD% 400 mg ± 1.63% 465 mg ± 0.85

Thickness 4.90 ± 0.02 mm 4.2 ± 0.06 mm

Hardness 11 Kp ± 0.61 10 Kp ± 0.69




Table 22: Percentage Drug Release of F7 Vs Marketed Product (Epivir HBV Tablets)

Sr. No. Time (hrs.) F- 7* Epivir HBV Tablets

1 0 0.00 0.00

2 1 18.06 19.34

3 2 29.34 31.66

4 4 47.54 50.44

5 8 71.56 75.67

6 12 86.36 89.70

7 16 98.85 99.01


Figure 29: Comparative Study between F7 & Marketed Product

Table 23: Stability Studies Profile

Time Drug Content

25º C + 2ºC, 60% RH 30º C + 2ºC, 65% RH 30º C + 2ºC, 75% RH

0 Day 100.06 100.02 99.98

30th Day 100.01 99.96 99.89

60th Day 99.64 99.42 99.22

90th Day 98.18 97.98 97.79



Figure 30: Stability Study of F7

Observation: No significant change in the prominent peak of drug in optimized formulation,

after accelerated stability study was found.

CONCLUSION

The study was undertaken with an aim to formulation development and evaluation of

Lamivudine sustained release tablets using polymers hydroxypropylmethylcellulose and

ethylcellulose. Lactose monohydrate was used as channeling agent and or as filler.

Preformulation study was done initially and results directed for the further course of

formulation. Based on preformulation studies different formulations of Lamivudine were

prepared using selected excipients. Powder and blends were evaluated for tests - bulk density,

tapped density, compressibility index, Hausner’s ratio before being punched as tablets. Tablets

were prepared by direct compression method by using 9 station single rotary tablet

compression machine with application of 6-7 tons pressure. After in process evaluations

(discussed below) tablets are packed in well closed moisture proof, light resistance container,

labeled, and kept at dry place. Tablets were tested for official and unofficial tests like- weight

variation test, thickness, hardness, friability and In vitro drug release as per official procedure

was performed to observe diffusion and release mechanism of drug through polymeric

membrane. From the above results and discussion it is concluded that formulation of sustained

release tablet of Lamivudine containing 80 mg of hydroxypropyl-methylcellulose E15 (high

viscosity grade) and 80 mg of ethylcellulose i.e. formulation F7 can be taken as an ideal or

optimized formulation of sustained release tablets for 16 hours release as it fulfills all the

97.5

98

98.5

99

99.5

100

100.5

0 20 40 60 80 100

Dru

g R

emain

ing %

Days in Time

25º C + 2ºC, 60% RH

30º C + 2ºC, 65% RH

40º C + 2ºC, 75% RH



requirements for sustained release tablet and our study encourages for the further clinical trials

and long term stability study on this formulation.

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