Studies on the dissolution and bioavailability of the rectal capsule of acetaminophene

Key words: 
• acetaminophene /
• rectal capsule /
• dissolution /
• bioavailability /

Abstract: The rectal capsule of acetaminophene was prepared, it can be formed several sizes by children's weight so as to administrate in personal. Tmax, Cmax and AUC of the capsule and the suppository commercial were 1.87, 1.67h; 54.86, 46.69(μg/ml); 198.94, 188.94 (μg·h/ml) in rabbits respectively, the results showed that the suppository of acetaminophene can be substitued by the rectal capsule, it was a new dosage form in rectal administration, it's dissolution in vitro was determined by the method of rotating-cylinder with millipore memberane(RCMM) established by ourself. There are a significant correlation between the cumulative dissolution rates in vitro and the absorption rates in vivo, and the both meets zero-order kinetics, the results showed that RCMM could simulated the dissolution of rectal capsule in rectal, it provided a new method of determing dissolution of soluble suppositories, RCMM can simulated the conditions of poor liquid, pH≈7, temperature higher than body temperature but cann't simulated the larger absorption area and the pressure of rectal acting on preparations in rectal, it has several advantages such as simple operating, fixed diffusion area, regulating millipore memberane and non-ignoring the differances of preparations.