Pharmacokinetic study of etodolac after rectal administration; "in vitro" release kinetics

The present study describes the pharmacokinetic behaviour of a new dosage form of etodolac not available in the Spanish market: suppositories. Rectal administration was chosen as an alternative for the oral route. The dose used was 200 mg. The pharmacokinetic parameters of the drug are estimated by means of two possible methods i.e., model-independent and model-dependent. The results obtained are compared and discussed. At the same time, an "in vitro" study of the release kinetics of etodolac from the suppository was performed using a continuous flow system without fluid recirculation or accumulating reservoir. The dissolution media used were buffered aqueous solutions at pH 6.5 and 7.4. The results obtained show that the release of the drug from the supposity could be a limiting factor for its absorption.