Single-step extraction for simultaneous quantification of desvenlafaxine and alprazolam in human spiked plasma by RP-HPLC

Desvenlafaxine (DES) and Alprazolam (ALP) are the drugs commonly prescribed together for the treatment of Major Depressive Disorders (MDD). A literature survey revealed, there is no method for the simultaneous determination of these two drugs. The purpose of this research was to develop and validate a simple, accurate, precise, robust, and isocratic RP-HPLC method for simultaneous determination of DES and ALP in human spiked plasma using UV-detector in short analysis time. The method utilized Hypersil BDS C18 (250 mmx4.6 mm, 5 [mu]m) through an isocratic mode of elution using HPLC grade acetonitrile and 0.02M KH.sub.2 PO.sub.4 buffer (65:35) and 0.1% Tri Fluoro Acetic acid (TFA) with pH 4.00 adjusted with 1M KOH. The flow rate was 1.00 mLmin.sup.-1 and elution of the drugs was monitored at 230nm. The elution time of DES and ALP was 4.011 and 5.182 minutes respectively. The method was linear for the concentration range 10-150 [mu]gmL.sup.-1 for DES and 5.0-75.0 [mu]gmL.sup.-1 for ALP. According to the validation results, the method is sensitive with Limit of Detection (LOD) 4.740 [mu]gmL.sup.-1 and Limit of Quantification (LOQ) of 14.365 [mu]gmL.sup.-1 for DES and LOD 1.891 [mu]gmL.sup.-1 & LOQ 5.730 [mu]gmL.sup.-1 for ALP. The reproducibility of results with minute deliberate variations in method parameters has proven that the method is robust. The data from stability studies show a non-significant change in drugs solutions for 2 months. The optimized method was validated as per International Conference for Harmonisation (ICH) Q2(R1) guidelines. This method can be used for the estimation of DES and ALP in plasma and can evaluate pharmacokinetic parameters of both drugs simultaneously.