Biopharmaceutical investigations of rectal suppositories. Part 1: Pharmaceutical and biological availability of theophylline.

: The influence of suppository base and some tensides on the release and resorption of theophylline from model rectal suppositories was investigated in a preliminary way. It was established that the original Bulgarian suppository base Novosup ensures higher pharmaceutical and biological availability of theophylline in comparison with other investigated lipophilic bases. The preliminary inclusion of Tween 80 in Witepsol H 15 increased the pharmaceutical and biological availability of the drug. A linear relationship between the pharmaceutical and biological availability was observed after administration of model suppositories in rabbits.