Statistical optimization of extraction process for the quantification of valsartan in rabbit plasma by a HPLC method

Sreenivasa, et al.: A Statistical Approach to HPLC Bioanalytical Method Development of Valsartan This article describes a high performance liquid chromatography method for determination of valsartan in rabbit plasma. The method was statistically optimized, developed and validated as per United States of Food and Drug Administration guidelines. The solvent deproteination technique was opted for the extraction of valsartan from rabbit plasma. Full factorial design was used for the optimization of an extraction method. The main effect of deproteinating agent, volume of deproteinating agent, speed of centrifugation and time of centrifugation was found to be significant at P<0.0001 on all the responses. After deproteinization, the drug was analysed on a C₁₈ column using 20 mM ammonium formate:acetonitrile (58:42 v/v) as the mobile phase with a flow rate of 0.9 ml/min. The standard calibration curve was constructed in the concentration range of 75 ng/ml to 4.0 μg/ml and linearity was found to be 0.9989. Losartan was used as the internal standard. The retention time of valsartan and the internal standard was found to be 11.394 and 6.343 min, respectively. No interference peak was perceived. From the accuracy results, the relative error was found between 0.99 and 13.01% and relative standard deviation was between 1.43 and 12.19%. The percent relative standard deviation of intra-day and inter-day precision was found to be less than 15%. Limit of detection and limit of quantitation were found to be 22.00 and 66.67 ng/ml, respectively. From pharmacokinetic applications, the peak plasma concentration (C_max) of valsartan oral suspension was found to be 1092.67±39.62 ng/ml at 0.67±1.24 h. The half-life and area under the curve were found to be 19.92±10.28 h and 8393.35±131.14 ng/ml, respectively. The high performance liquid chromatography method was successfully demonstrated as rapid and sensitive method which can be used as an alternative for the analysis of valsartan in plasma samples.