Assay of lercanidipine hydrochloride in dosage forms using nucleophilic substitution reaction.

A simple and sensitive spectrophotometric method has been developed for the assay of lercanidipine hydrochloride (LER) in bulk and in formulations. The method is based on the formation of coloured species between the drug and 1,2-naphthaquinone-4-sulphonic acid sodium salt (NQS) by means of nucleophilic substitution reaction. Absorbance was measured at λ(max) = 460 nm. The method was analyzed statistically. The system obeyed the Beer's law in the range 20-100 μg mL⁻¹. Molar absorptivity value was found to be 4.79 × 10³ L mol⁻¹ cm⁻¹. Limits of detection and quantification were found to be as low as 0.04 and 0.13 μg mL⁻¹. Precision (RSD, 0.4%) and accuracy (recovery 99.2 ± 0.6 to 101.1 ± 0.8%) of the developed method were evaluated.