Patel Satish A

A simple, specific, accurate and precise reverse phase high performance liquid chromatographic (RP-HPLC) method was developed with high sensitivity for determination of Valsartan and Hydrochlorothiazide drugs in combined dosage forms. The separation was achieved on Zorbax CN (25 cm x 4.6 mm, 5 µm) at flow rate of 1.8 ml/min with 70: 30 mixture of phosphate buffer: acetonitrile (pH 6) as the mobile phase. The quantification was achieved with PDA detector at 265 nm. The injection volume was 20 μl. The retention times of Valsartan and Hydrochlorothiazide were 6.04 min and 2.27 min, respectively. The method was validated for linearity, precision, specificity, robustness and recovery according to the ICH guidelines. The linearity of response for Valsartan and Hydrochlorothiazide were assessed by analysis of five independent levels of calibration curve in range of 20-100 µg/ml and 2-10 µg/ml respectively. The recovery data was between 98.77-99.73% and 98.75-100.56% for Valsartan and Hydrochlorothiazide respectively. The limit of detection and quantification for Valsartan were 0.98 and 2.97μg/ml respectively and for Hydrochlorothiazide were 0.18 and 0.57μg/ml, respectively. The method was found to be simple and highly sensitive and can be useful in the routine quality control of Valsartan and Hydrochlorothiazide in bulk manufacturing and pharmaceutical dosage forms.

  A simple, specific, accurate and precise reverse phase high performance liquid chromatographic method was developed for simultaneous estimation of diazepam and propranolol hydrochloride in pharmaceutical tablet formulation. The separation was achieved on Phenomenex C18 column (250 mm i.d., 4.6 mm, 5 µm particle size) using methanol: acetonitrile: water (50 : 25 : 25, v/v/v, pH adjusted to 2.8 ± 0.05 with ortho- phosphoric acid) as the mobile phase at a flow rate of 1.0 ml min-1. The quantification was achieved with PDA detector at 235 nm. The injection volume was 20 µl. The retention times of diazepam and propranolol hydrochloride were 5.38 ± 0.29 min and 3.80 ± 0.15 min, respectively. The method was validated for linearity, precision, specificity, robustness and recovery according to the ICH guidelines. The linearity was obtained in the concentration range of 0.1-5.0 µg/ml for both drugs with mean recovery of 100.3 ± 0.47 and 100.2 ± 0.78 % for diazepam and propranolol hydrochloride, respectively. The limit of detection and quantification for diazepam were 0.015 and 0.050 µg/ml, respectively and for propranolol hydrochloride were 0.014 and 0.045 µg/ml, respectively. The method was found to be simple and highly sensitive and can be useful in the routine quality control of diazepam and propranolol hydrochloride in bulk manufacturing and pharmaceutical dosage forms.   Key words: Diazepam, propranolol hydrochloride, RP-HPLC, validation, simultaneous, tablet