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Nutrient influences on rat intestinal phenytoin uptake
D Fleisher1, N Sheth, H Griffin
1College of Pharmacy, University of Michigan, Ann Arbor, 48109.
Pharmaceutical Research
|April 1, 1989
Summary
Phenytoin intestinal absorption varies by region and is influenced by glucose and calcium. The in vitro model did not fully replicate these drug-nutrient interactions observed in vivo.
Area of Science:
- Pharmacology
- Gastroenterology
- Drug Absorption
Background:
- Phenytoin is an antiepileptic drug with variable oral absorption.
- Understanding drug-nutrient interactions is crucial for optimizing phenytoin therapy.
Purpose of the Study:
- To investigate the intestinal uptake of phenytoin.
- To determine the influence of intestinal region, glucose, and calcium chloride on phenytoin absorption.
Main Methods:
- Utilized in situ rat intestinal perfusion and in vitro everted intestinal ring systems.
- Measured steady-state membrane permeabilities and initial rates of tissue uptake.
- Assessed effects of varying phenytoin concentrations, glucose, and calcium chloride.
Main Results:
- Phenytoin permeability was concentration-independent and decreased from duodenum to ileum.
- Glucose enhanced permeability, while high calcium chloride decreased it in perfusion studies.
- In vitro studies showed concentration-independence and calcium chloride effects but lacked regional variation and glucose enhancement.
Conclusions:
- Intestinal absorption of phenytoin is region-dependent and modulated by nutrients like glucose and calcium.
- The observed drug-nutrient interactions are dependent on the experimental isolation procedure.
- In vitro models may not fully recapitulate in vivo intestinal drug absorption dynamics.