Abstract

Sildenafil citrate is a selective inhibitor of phosphodiesterase type 5 enzyme (PDE5) extensively used for the treatment of erectile dysfunction (ED). Sildenafil citrate is BCS class II drug, practically insoluble in water. It’s absolute bioavailability is 41% and half life is 4 hours. Aspirin is a Cyclooxygenase Inhibitors (COX-1 & COX-2) having a mechanism by dilating blood vessels in vivo, probably through direct effect on vascular smooth muscle. Therefore, the vasodilator action of aspirin which dilates the blood vessels gives synergistic effect to Sildenafil Citrate. The active pharmaceutical ingredients (APIs) in crystalline forms are more promising towards the stability, reproducibility and purification of the same in comparison to other types of solid forms, hence having the most priority in comparison to other forms. The properties like dissolution rate and intrinsic solubility of several crystalline forms are different and thus are playing an important role in enhancing the bioavailability. The stability with respect to temperature and humidity are more significantly depending on packaging of crystals. Sildenafil Aspirin Pharmaceutical co-crystals were successfully engineered with succinic acid as coformer under reflux condition. A new solid phase (cocrystals) was characterized by Fourier transformation infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), powder X-ray diffractometry (PXRD). Physical characterization showed that Sildenafil Aspirin cocrystalline phase had unique thermal, powder X-ray diffraction property. The physicochemical properties of pure Sildenafil and corresponding co-crystals were accessed in terms of melting point, drug content uniformity, dissolution studies. The rapid rate of dissolution of cocrystals was observed in initial 10 min. The extent of dissolution was also enhanced on account of cocrysatllization.