PHARMACEUTICS- PHARMACEUTICS- IVIV

(PHT 414 ) (PHT 414 )

Dr. Mohammad Khalid AnwerDr. Mohammad Khalid Anwer

SALMAN BIN ABDUL AZIZ UNIVERSITY

COLLEGE OF PHARMACY

L8 104/21/23

Nature and type of dosage forms:-

Solutions Suspensions

Tablets Capsules

Coated tab Enteric coated tab

Excipients and adjuvant

Product age and storage conditions.

Disintegration test

Dissolution test

Pharmaceutical Factors Pharmaceutical Factors

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NATURE AND TYPE OF DOSAGE FORM

MEANS Absorption rate depends on the dosage

Form which is administered, ingredients used, proceduresUsed in formulation of dosage forms. The availability of the drug for absorption from the dosage forms is in order.

Solutions > Suspensions > capsules > Compressed Tablets > Coated tablets.

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SOLUTIONSShows maximum bioavailability and factors affecting

Absorption from solution are as follows

1.Chemical stability of drug

2.Complexation: between drug and exipients of formulation

to increase the solubility, stability.

3. Solubilization: incorporation of drug into micelles to increase the solubility of

drugs.

4. Viscosity

5. Type of solution: Whether aqueous or oily solution.

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SUSPENSIONS:

It comes next after solutions with respect to bioavailability

Factors that affects absorption from suspensions are

1.Particle size and effective surface area of dispersed phase

2. Crystal form of drug: some drug can change their crystal

structure.

Eg. Sulfathiazole can change its polymorphic form, it can be

overcome by addition by adding PVP.

3. Complexation: Formation of nonabsorbable complex between

drug and other ingredients.

Eg. Promazine forms a complex with attapulgite.

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4. Inclusion of surfactant

Eg. The absorption of phenacitin from suspension is increased in

presence of tween 80.

5. Viscosity of suspension

Eg. Methyl cellulose reduces the rate and absorption of

nitrofurantoin

6. Inclusion of colourants:

Eg. Brilliant blue in phenobarbitone suspension.

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CAPSULES

Two types of capsule

1.Hard gelatin capsule

2. Soft gelatin capsule

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Capsules For hard gelatin capsules the shell should disrupt quickly and expose the contents to the GI fluids.

Factors influencing are particle size, density, crystal form of the drug, selection of diluents.

For hydrophobic drugs with a fine particle size in capsule results in decrease in porosity of the powdered drug and thus decreased penetrability by the solvent which results clumping of particle.

soft elastic capsule dissolve faster than hard gelatin capsule & tablets. Which shows better bioavailability from oily solutions, emulsions, or suspensions.

The problem with SGC is high water content of shell, moisture migrate in to the shell causes crystallization of the drug results in altered dissolution characteristics .04/21/23 8L8

HARD GELATIN CAPSULE

The rate of absorption of drugs from capsule is function

Of some factors.

1.Dissolution rate of gelatin shell.

2.The rate of penetration of GI fluids into encapsulated mass

3.The rate at which the mass disaggregates in the GI fluid

4. The rate of dissolution.

5. Effect of excipients;

a).Diluents

b).Lubricants

c). Wetting characteristics of drug

d).Packing density

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SOFT GELATIN CAPSULE

SGS has a gelatin shell thicker than HGS, but shell is plasticized by adding

glycerin, sorbitol.

SGS may used to contain non aqueous solution or liquid or semi solid.

SGC have a better bioavailability than powder filled HGC and are equivalent to

emulsions.

Eg. Quinine derivative was better absorbed from SGC containing drug base

compared with HGC containing HCl salts.

Grieseoflavin exhibited 88% absorption from Soft Gelatin Capsules compared

to HGC(30%)

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TABLETS

1.Compressed tablets

2. Coated tablets

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Compressed Tablets

This is the most widely used dosage form.

Problem with this arises from reduction in the effective surface area

due to granulation & subsequent compression in to dosage form.

Tab disintegration and granule disaggregation are the imp steps in

absorption process.

Compression force also may be an important factor.

Disintegration is the rate limiting step for this.

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Compressed tabletsBioavailability are more due to large reduction in surface area.

Intact tablets a granules primary drug particlesA B

Drug in GI fluid

Drug absorbed in body

K1K2

K3

K4

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The rate constants decrease in the following order.

K3>>K2>>K1

The overall dissolution rate and bioavailability of a poor

Soluble drugs is influenced by

1.The physicochemical properties of liberated particles.

2. The nature and quantity of additives.

3. The compaction pressure and speed of compression.

4. The storage and age of tablet

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1.Effect of diluents :

Na Salicylates + starch = Faster dissolution

Na salicylates + lactose=Poor dissolution.

2.Effect of Granulating agent:

Phenobarbital + Gelatin solution=Faster dissolution

Phenobarbital+PEG 6000= poor dissolution.

3.Effect of lubricants:

Magnesium stearate will retard the dissolution of aspirin tablet

Whereas SLS enhance the dissolution.

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4.Effect of disintegrants:

Starch tend to swell with wetting and break apart the dosage

form. It is reported that 325mg of salicylic acid tablet were

prepared by using different concentrations (5%,10%,20%) and

max. dissolution was achieved With 20% starch.

5. Effect of colorants:

6.Effect of Compression force:

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Coat is generally used to mask unpleasant taste & odor & to

protect the ingredients from decomposition during storage.

This adds an additional barrier between GIT & drug. It should

get dissolve before tablet disintegration & dissolution.

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Coated tablets

L8

COATED TABLETS Cont……………..:There are three types of coatingSugar coatingFilm coatingEnteric coating

Sugar coating will take more time than film coating.

Care should be taken while selecting the coating material

Ex: methyl cellulose which retards the dissolution

SUGAR COATING:Sugar,Shellac,fatty glycerides, bees wax, silicone resinSub coating agent: Talc,acacia,starch.

FILM COATING:Polymers, dispersible cellulose derivatives like HPMCCMC.

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Enteric coated tablets

It is a special film coated design to restricts the gastric fluids & to

dissolve in small intestine.

Protect the drug from the degradation in the stomach Ex:

erythromycin.

Minimize the gastric distress caused by some drugs. Ex: aspirin.

These tablets must empty the stomach before the drug absorption can

begin.

The polymers with pKa values ranging from 4-7 have been found to

use.

Shellac, cellulose acetate phthalate etc.

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