PHARMACEUTICAL EVALUATION OF CARBAMAZEPINE SUPPOSITORIES IN RATS

The absorption of carbamazepine (CBZ) after rectal administration in t he form of a suppository was studied in rats. CBZ suppositories were p repared with Witepsol H-15 (H-15), Witepsol S-55 (S-55) or polyethylen e glycol 6000 (PEG) bases by moulding procedure. An in vitro investiga tion was undertaken using a dissolution apparatus. The in vitro dissol ution rate of CBZ showed marked differences among the bases in the ord er PEG > H-15 > S-55. An in vivo study demonstrated marked differences in the time required to reach peak plasma concentration (T-max) of CB Z after rectal and oral administration: the absorption of CBZ from PEG base was the most prolonged among these bases (in the order PEG > H-1 5 > S-55 > oral). Comparison of the area under the plasma concentratio n-time curve (AUC) of CBZ after rectal administration of the three dif ferent suppositories with those after intravenous and oral administrat ion showed no significant differences in the AUC among the five prepar ations. These results suggest the possibility that CBZ suppositories c an replace oral treatment for epilepsy.