Development and validation of an HPLC-UV method for accelerated stability study and pharmacokinetic analysis of venlafaxine

A reverse phase high performance liquid chromatography method has been developed and validated for accelerated stability study and determination of pharmacokinetic parameters of venlafaxine HCl. The chromatographic separation was carried out using ODS analytical column (250 x 4.6 mm i.d., 5 mu m particle size). The mobile phase included acetonitrile, methanol and potassium dihydrogen phosphate buffer (30:30:40; pH 6.1) at a flow rate 1.5 mL min(-1). UV-Visible detector was used at wavelength of 227 nm to monitor elutions. Retention time observed was 2.745 min. The method was validated for linearity, accuracy, precision, sensitivity and robustness. Accelerated stability study of venlafaxine HCl capsules was carried out at 40 and 50 degrees C under 75% RH level. Suggested method was successfully applied for the pharmacokinetic analysis of venlafaxine hydrochloride tablets. Each of ten albino rabbits (=1.2 kg each) was orally administered with 5 mg dose of venlafaxine HCl. The method was proved to be linear (R-2 >0.998), accurate (98.25-99.27%), sensitive (LOD: 35ng mL(-1); LOQ: 105 ng mL(-1)) and robust (RSD<1%). The drug showed stability at accelerated conditions of temperature and humidity. The main pharmacokinetic parameters of tested products were as follows: t(max) was 2.5h, C-max was 56.5 mu g mL(-1), t(1/2 )was 8.2 h, AUC(0-36) was 845.9 mu g h mL(-1). The developed method is suitable to apply for quality control analysis and pharmacokinetic studies.