Spectrophotometric method of estimation of Amlodipine besylate using hydrotropic solubilization

A novel, simple, fast and reproducible UV spectrophotometric method was developed using 2M urea solution as hydrotropic solubilizing agent for the estimation of poorly watersoluble drug amlodipine besylate in bulk and in pharmaceutical dosage form. Various organic solvents such as methanol, chloroform, dimethyl formamide and acetonitrile have been employed for solubilization of poorly water-soluble drugs to carry out spectrophotometric analysis. Drawbacks of organic solvents include their higher cost, toxicity and pollution. Hydrotropic solubilization may be a proper choice to preclude the use of organic solvents. It involve the addition of large amount of a second solute to increase the aqueous solubility of the first solute. Amlodipine exhibits absorption maximum at 243 nm. Urea did not show any absorbance above 225 nm and thus no interference in the estimation of drug was seen.Beer’s law was found to be obeyed in the concentration range of 5-25µg/mL. In this method, there is no interference from any common pharmaceutical additives and diluents. The correlation co-efficient (' r ' value) for amlodipine was0.99863.The results of analysis have been validated as per ICH guidelines. The percentage recoveries obtained for amlodipine ranges from 99.94 to 99.96. The method is accurate, precise and economical.