Enhanced absorption of phenobarbital from suppositories containing phenobarbital-.BETA.-cyclodextrin inclusion complex.

Abstract

Phenobarbital [a anticonvulsant] was dissolved faster from a .beta.-cyclodextrin complex than from phenobarbital powder, and it was released faster from suppositories containing its .beta.-cyclodextrin complex than from those containing phenobarbital powder. After rectal administration of the suppository containing the .beta.-cyclodextrin complex to rabbits, the blood concentration of the drug was higher than that following administration of the phenobarbital suppository. Since .beta.-cyclodextrin tended to retard absorption of the drug in solution from the rectum, enhanced absorption of the drug from the complex was attributed to fast release from the suppository due to rapid dissolution.