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

(e)- Alteration of gastric emptying

Enteric-coated tablets or non-disintegrating dosage forms may stay in the stomach

for a longer period of time because food delays stomach emptying.
Fatty food can slow gastric emptying and retard drug absorption, thus delaying the

onset of action of certain drugs.

(f)- Stimulation of GI secretions
✓ GI secretions (e.g. pepsin) produced in response to food may result in the

degradation of drugs that are susceptible to enzymatic metabolism, and hence

in a reduction in their bioavailability.

✓ The ingestion of food, particularly fats, stimulates the secretion of bile.

✓ Bile salts are surface active agents and can increase the dissolution of poorly

soluble drugs, thereby enhancing their absorption.

✓ In contrast, bile salts have been shown to form insoluble and hence non-

absorbable complexes with some drugs, such as neomycin, kanamycin and

nystatin.

(g)- Increased viscosity of gastrointestinal contents

The presence of food in the GIT provides a viscous environment which may result

in:

✓ Reduction in the rate of drug dissolution,

✓ Reduction in the rate of diffusion of drug in solution from the lumen to the

absorbing membrane lining the GIT.

✓ Hence, there is reduction in drug bioavailability.

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