Abstract
The effect of different concentrations (5, 10 and 20% w/w) of polycarbophil on the in vitro release and in vivo availability of dihydroergotamine mesylate from polyethylene glycol suppositories was studied. In vitro release data showed that as the polycarbophil concentration in the suppositories increased, the release rate decreased. The in vivo data revealed that suppositories containing 5% polycarbophil resulted in a significant (
p < 0.05) reduction in C
max and non-significant decrease in AUC and produced 62% relative bioavailability compared to that of polyethylene glycol suppositories containing 0% polycarbophil (control). The addition of 10% polycarbophil to the suppository formulation resulted in a lower reduction in C
max and AUC than the addition of 5% and gave 78.9% relative bioavailability. The suppositories containing 20% polycarbophil produced higher C
max, AUC, and relative bioavailability (127%) compared to the control. The concentration of polycarbophil in dihydroergotamine suppository formulations is critical in determining the release rate of the drug and its bioavailability.