This paper describes a new, simple, precise, and accurate HPTLC method for simultaneous estimation of Losartan potassium and Metolazone as the bulk drug and in tablet dosage forms. Chromatographic separation of the drugs was performed on aluminum plates precoated with silica gel 60 F254 as the stationary phase and the solvent system consisted of toluene : ethyl acetate : methanol : glacial acetic acid (6 : 4 : 1 : 0.1 v/v/v/v). Densitometric evaluation of the separated zones was performed at 237 nm. The two drugs were satisfactorily resolved with RF values 0.33 ± 0.02 and 0.46 ±0.02 for Losartan potassium and Metolazone respectively. The accuracy and reliability of the method was assessed by evaluation of linearity (60-210 ng/spot for Losartan potassium and 120-420 ng/spot for Metolazone, precision (intra-day % RSD was 1.28 – 1.58 and inter-day % RSD was 1.14 – 1.83 for Losartan potassium and intra-day % RSD was 0.67 – 1.03 and inter-day % RSD was 0.49 – 1.18 for Metolazone), accuracy 99.58 ± 0.15 for Losartan potassium and 99.40 ± 0.39 for Metolazone), and specificity in accordance with ICH guidelines.
