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Absorption of rectally administered phenytoin: a pilot study
S W Chang1, J H da Silva, D R Kuhl
1Pharmacy Department, St. Paul's Hospital, University of British Columbia, Vancouver, Canada. schang1234@hotmail.com
The Annals of Pharmacotherapy
|August 31, 1999
Summary
Rectal administration of phenytoin in healthy volunteers showed absorption beginning within 30 minutes. This pilot study indicates rectal phenytoin absorption is feasible, though further research is needed for patient populations.
Area of Science:
- Pharmacology
- Gastroenterology
Background:
- Phenytoin is an anticonvulsant medication.
- Rectal administration may be an alternative route for drug delivery.
Purpose of the Study:
- To evaluate the rectal absorption of phenytoin in healthy volunteers.
- To compare rectal versus intravenous administration of phenytoin.
Main Methods:
- A single-center, open-label crossover pilot study.
- Twelve healthy volunteers received intravenous and rectal phenytoin (7 mg/kg).
- Serial blood samples were analyzed for phenytoin concentrations over 36 hours.
Main Results:
- Rectal administration of phenytoin resulted in a mean apparent bioavailability of 24.4%.
- Phenytoin was detected in blood samples within 30 minutes of rectal administration.
- Maximum concentrations (Cmax) were achieved within 1-2 hours for both administration routes.
Conclusions:
- Rectal administration of phenytoin is absorbed in healthy volunteers.
- Four out of five volunteers preferred the rectal route.
- Further studies are necessary to confirm findings in patient populations.