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 C-18 (150 mmx 4.6 mmID, 5 mu m particle size) analytical column, whichwas maintained at 30 degrees 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 mu g mL(-1) for HCT and 10.0-60.0 mu g 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.