Effect of Amphiphilic Graft Co-Polymer Carrier on Solubility and Dissolution Enhancement of Ambrisentan

Abstract

Aim: Ambrisentan is a endothelin type A selective receptor antagonist used in the management of pulmonary arterial hypertension. Ambrisentan is BCS Class II drug haves very poor solubility in water and shows incomplete absorption after oral administration. The present work was aimed to study the effect of amphiphilic graft co-polymer carrier on enhancement of solubility and dissolution rate of poorly water soluble drug ambrisentan. To improve the aqueous solubility of ambrisentan solid dispersion was formulated by using novel carrier amphiphilic graft co-polymer (Soluplus® ).
 Materials and Methods: Solid dispersion was prepared by kneading technique by utilizing various ratios of carrier. Obtained solid dispersions ware evaluated for solubility, percentage yield, drug content and in vitro dissolution study. Powder characterization was performed by infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), and X-ray diffraction (XRD).
 Results: FTIR spectroscopy shows no interaction between drug and polymer. DSC study showed that endothermic peak of drug was completely disappeared in Solid dispersion suggesting complete miscibility of drug in Soluplus®. XRD study suggest the conversion of crystalline ambrisentan in to amorphous form. All solid dispersions prepared with Soluplus® as a carrier showed increase in solubility. Solubility of ambrisentan was found to be increased 7.17 fold in optimized SD formulation ASD5. In vitro dissolution study showed the faster drug release from SD formulation compare to its pure form. All solid dispersion formulation’s release more than 50% of drug in first 10 min.
 Conclusion: This study conclude that the preparation of amphiphilic graft co-polymer based solid dispersion prepared by kneading technique is found to be useful in enhancement the solubility and dissolution rate of ambrisentan.