The tablet was finely powdered and powder equivalent to 100 mg of BH was accurately weighed transferred to a 100 ml volumetric flask containing about 75 ml selleck screening library of the mobile phase. The powder mixture was dissolved in the mobile phase with the aid of ultrasonication. The solution was filtered through Whatman filter paper no. 41 into another 100 ml volumetric flask. Washed the filter paper with the mobile phase and added the washings to the filtrate. Volume of filtrate was made up to the mark with the mobile phase. To another 10 ml volumetric flask, 1 ml of this solution was transferred and the volume was made up to the mark with the mobile phase. To another 10 ml volumetric flask, 4.0 ml of this solution was transferred and the volume was made up to the mark with the mobile phase.

This solution was filtered through a 0.2 ��m membrane filter. After setting the chromatographic conditions and stabilizing the instrument to obtain a steady baseline, the tablet sample solution was loaded in the 20 ��L sample loop of the injection port of the instrument, and the peak areas were recorded. A representative chromatogram has been given in Figure 1. The peak areas of each of the drug were recorded and the amount of each drug present per tablet was estimated from the respective calibration curves. The procedure of analysis was repeated five times with two different tablet formulations [Table 4]. Table 4 Results of analysis of commercial formulation* Recovery studies Recovery studies were carried out for formulation by addition of known amounts of standard drug solution to pre-analyzed tablet sample solution at three different concentration levels.

The resulting solutions were analyzed by the proposed method. The results of recovery studies were found to be satisfactory [Table 5]. Table 5 Results of recovery studies RESULTS AND DISCUSSION In this work the HPLC method has been developed for simultaneous estimation. The developed HPLC method for simultaneous estimation of BH and TB make use of a C8 column. The mobile phase used for this method was phosphate buffer:acetonitrile (70:30) and detection of eluent was carried out at 270.0 nm. The total run time of this method was less than 20 min and the retention time for BH was found to be at 15.50 min while that of TB was 9.85 min at a flow rate of 1.0 ml/min, respectively. Percentage label claim of tablet formulation using this method was found to be 99.

35% for BH and 99.70% for TB, respectively. Standard deviation was found to be 0.225�C0.351 for BH and 0.0.236�C0.264 for TB for two different batch of tablet formulation. CONCLUSION The developed HPLC method was found to be simple, specific, precise, accurate, and reproducible for the routine analysis of two drugs from a combined dosage form available in the market. GSK-3 ACKNOWLEDGMENTS The authors are thankful to Swami Keshvanand Institute of Pharmacy, Raisar, Bikaner, Rajasthan (India), for providing laboratory facilities.