Simultaneous Determination of Hydrochlorothiazide and Losartan Potassium in Osmotic Pump Tablets by Microemulsion Liquid Chromatography.

A rapid and efficient oil-in-water microemulsion liquid chromatographic (MELC) method has been optimized and validated for the determination of hydrochlorothiazide (HCT) and losartan potassium (LOP) in osmotic pump tablets. Samples were injected into a C18 (150 mm × 4.6 mm ID, 5 µm particle size) analytical column, which was maintained at 30°C. The most effective MELC system had a mobile phase consisting of 95% (v/v) of 3.0% (w/w) SDS, 6.0% (w/w) n-butanol, 0.8% (w/w) n-octane, 90.2% (w/w) water and 5% (v/v) acetonitrile (pH 5). The flow rate was 1.0 mL min(-1) and UV detection was performed at 265 nm. Linearity ranged from 2.5 to 12.5 µg mL(-1) for HCT and 10.0-60.0 µg mL(-1) for LOP (r > 0.999 for both drugs). The proposed method was rapid, precise (RSDs < 1.4%) and accurate (98.9% recovery for HCT and 101% recovery for LOP). It is applicable to simultaneous determination of HCT and LOP in osmotic pump tablets.