In vitro evaluation and in vivo pharmacodynamic studies of spironolactone suppositories administered to rats

In vitro release of spironolactone from different suppository bases and in vivo pharmacodynamic effect in rats were studied. Suppositories containing 10 mg of spironolactone were prepared using polyethylene glycol [PEG], Witepsol E75, theobroma oil and Suppocire A. The hardness test of the suppositories revealed that the theobroma oil base produced relatively brittle suppositories, whereas polyethylene glycol base, in particular mixture of 1000: 4000 produced hard and stable suppositories. The release of spironolactone was fast from polyethylene glycol bases. Incorporation of Tween 80 in lipophilic bases remarkably enhanced the release of spironolactone from these bases. Using the dialyzing technique to study release characteristics of the drug from the suppositories, the maximum release of the drug was obtained from Witepsol E75 suppositories containing 5%Tween 80 followed by release from PEGs. The suppository formulations were evaluated for their pharma effect in rats. The in vivo data showed that the different suppository formulations had a significant influence on the extent of spironolactone dynamic effect. Among these suppository bases, the hydrophilic polyethylene glycol 1500, Witepsol E75+5% Tween 80 and theobroma oil were found to be the best