Development and Validation of a Novel, Cost Effective UV Spectrophotometric Method for Simultaneous Estimation of Cilnidipine and Olmesartan

Abstract

Cilnidipine is a novel, dihydropyridine class of calcium-channel blocker. It prevents intracellular calcium influx and results in vasodilatation. Olmesartan medoxomil is a synthetic imidazole derivative prodrug and angiotensin II type blocker used to manage hypertension. The combination of cilnidipine and olmesartan medoxomil is used in the treatment of hypertension. Literature review revealed that there are many analytical methods involving HPLC and some using UV for estimation of the two drugs individually and in combination. UV spectrophotometric methods have the advantage of being simple, cost effective and rapid. Hence it was thought worthwhile to develop a simple, cost effective UV spectrophotometric method for simultaneous estimation of cilnidipine and olmesartan medoxomil employing the Absorption Correction principle. In this method, water: methanol (80:20,v/v) was used as the diluent. From the UV overlain spectra of both the drugs 257nm and 365nm were selected as wavelengths for analysis. The method was validated using the ICH guidelines. The linearity range was established from 10-100µg/ml (r2= 0.999) for cilnidipine and 10-80 µg/ml (r2= 0.998) for olmesartan medoxomil. The developed method was found to be accurate as % recovery at 80%, 100% and 120% levels were found to be within the acceptance criteria. The results for intra-day and inter-day precision were within acceptance limits of % RSD ˂ 2%. The method was found to be sensitive and robust. The developed method was applied in the estimation of Cilnidipine and Olmesartan in tablet dosage form and % assay was found to be 100.75% and 103.8% for the two drugs respectively. Hence the developed method can be employed as a simple, cost effective, quality control analytical method for simultaneous estimation of the two drugs in bulk and in combination.