Effect of binary and ternary systems on the physico-chemical properties and dissolution rate of spironolactone

Spironolactone [SP] was coprecipitated with both B-cyclodextrin [B-CD] and PVP. Ternary systems of drug: PVP: B-CD were also prepared by four different methods: 1- Drug: B-CD coprecipitate mixed with PVP, system [A], 2- Drug: PVP coprecipitate mixed with B-CD, system [B], 3-flash evaporation from 50% ethanol, system [C], and 4-Deposition of drug: PVP on B-CD, system [D]. All systems were evaluated by powder X-ray diffraction, DSC, IR and dissolution from tablets. The results revealed that the drug crystal peaks disappeared at ratio exceeds 1:4 SP; B-CD coprecipitates and two broad peaks [attributed to inclusion complex] appeared. The flash evaporated ternary systems showed the amorphous form of the drug. The drug dissolution rate from 1:6 binary drug; Polymer was in the following order; drug: PVP [chloroform > drug: B-CD > drug: PVP [ethanol]. The dissolution rate of the drug was enhanced using the ternary systems and this enhancement was found to be dependent on the polymer type, solvent of coprecipitation, method of preparation, and the ratio of each polymer in the system. The results of ternary systems were compared to that of binary coprecipitates