ENHANCEMENT OF RECTAL ABSORPTION OF RIFAMPICIN BY SODIUM PARA-AMINOSALICYLATE DIHYDRATE IN HUMAN-SUBJECTS

The suppositories of rifampicin (RFP) containing sodium para-aminosali cylate dihydrate (PAS-Na) were prepared in order to enhance the rectal absorption of RFP. By the addition of PAS-Na, the in vitro release of RFP from the suppositories was enhanced and the hardness of the suppo sitories decreased. The rectal absorption of RFP from the suppositorie s containing no PAS-Na (control suppositories) was significantly lower compared to oral administration of it (26%) in human subjects. When P AS-Na was added to the suppository (300 mg), both the area under the p lasma concentration-time curve (AUC) and the maximum plasma concentrat ion (C-max) increased significantly compared to those of the control s uppositories. The rectal absorption of PAS-Na itself from the supposit ories seemed to be fast. PAS-Na might increase the absorption of RFP d issolved in the rectal fluid from the suppositories, but not affect th e undissolved RFP.