Rectal Absorption of Aminophylline Suppository

Mode of rectal absorption of aminophylline was examined with 3 kinds of suppository bases, macrogol, Vosco H-15, and Vosco S-55. Plasma concentration of theophylline after rectal and oral administration was also measured on the subjects of 5 healthy adults. Measurement was made by the high-pressure liquid chromatography. Drug releasing test was made by the method of Kakemi et al. Physical property, melting point, dissolution time, and other properties of the suppository were measured. The drug releasing test demonstrated that the release of aminophylline from macrogol base was faster than that from Vosco bases (in vitro test). Plasma concentration of theophylline was found higher in the oleaginous base (Vosco) than in the water-soluble base (macrogol). This is contradictory to the finding in vitro test. In the human experiment, the highest mean plasma concentration of theophylline, 1.29 μg/ml., was observed 1 hour after rectal administration. The highest plasma concentration by rectal administration was slightly lower than that by oral administration.