Page 124 - Interactive Theoritical Notes of Bioharmaceutics and pharamcokinetics.docx compressed

PharmD clinical pharmacy program Level 3, Semester 2 Biopharmaceutics & Pharmacokinetics (PT608(

 Hydrophilic diluents form hydrophilic coat around hydrophobic drug particles –thus

promotes dissolution and absorption of poorly soluble hydrophobic drug.

2. Surfactants

• Surfactants are usually employed as emulsifying agents, solubilizing agents, and

suspension stabilizer as wetting agents in dosage forms.

• This wetting effect may aid the penetration of GIT fluids into the solid dosage

forms and increase the dissolution and absorption rates of the drug.

3. Glidants and lubricants

• Magnesium stearate in excessive quantities may cause slow absorption due to

retardation of the dissolution.

• Also, talc when used as glidant in vitamin B12 tablets, prevent the absorption of

the vitamin.

4. Viscosity enhancing agents

• They may alter the GIT absorption of drugs by;

✓ Complex formation

✓ Increasing the viscosity of GIT content which leads to

• Decrease the in gastric emptying rate,

• Decrease the intestinal motility and decrease the dissolution rate of
the drug
e.g. Hydrophilic polymers like starch, methylcellulose, CMC.

ii). Influence of the type of dosage form

Since a drug must be in solution to be absorbed from the GI tract, you may expect the

bioavailability of a drug to decrease in the order:

Solution > suspension > capsule > tablet > coated tablet

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