Comparison of Microemulsion and Solvent Evaporation Technique for Solubility Enhancement of Amlodipine Besylate

Introduction: Amlodipine besylate is a calcium channel blocker indicated for hypertension and angina. It is described as slightly soluble in water and due to its limited solubility, it may result in poor bioavailability. The aim of this study is to enhance the solubility of amlodipine besylate using solvent evaporation method and microemulsion technique and to compare the two methods. Method: Solid dispersions (SD) of amlodipine besylate were developed by employing solvent evaporation method. PEG6000 was the polymer of choice and different drug:polymer ratios were used. Evaluation of the prepared SDs include solubility studies, dissolution studies and scanning electron microscopy (SEM). As for the microemulsion technique, microemulsions were prepared by phase titration method and the optimized microemulsion formulation was then characterized for solubility studies and dissolution studies. Results: SD3 with drug:polymer ratio of 1:4 achieved the highest solubility which was 96.97 mg/ml ± 0.92 whereas the solubility of the optimized microemulsion was found to be 112.54 mg/ml ± 0.92. In solvent evaporation method, as the drug:polymer ratio increases, the solubility and dissolution rate of SDs increases. Conclusion: The two methods had significantly enhance the solubility of amlodipine besylate however the microemulsion technique showed better solubility profile.