Determination of Venlafaxine and Modafinil in Individual Tablet Dosage Forms using Single RP-HPLC Method

Purpose: To develop a simple and selective isocratic method for the determination of venlafaxine and modafinil in tablet dosage forms.Methods: The compounds were analyzed on Waters symmetry C18 column (4.6 mm x 250 mm i.d, 5ìm) using a mobile phase consisting of a mixture of ammonium acetate buffer (pH was adjusted to 4.0 with glacial acetic acid):10 % methanol in acetonitrile, in the ratio of 60:40. The flow rate was 1.0 ml/min and column effluents were monitored at 225 nm. The method was validated according to ICH guidelines.Results: Venlafaxine and modafinil were eluted with retention times of 4.416 min and 6.443 min, respectively. The method was linear in the range of 1.0 - 50 ìg/ml for both venlafaxine and modafinil. The relative standard deviation (%RSD) was < 1 for both drugs while mean recovery values at different concentration levels were within limits. The performance of the method was not changed when small variations in the method were made.Conclusion: The proposed method is accurate, reproducible and low-cost, and can be used for the routine analysis of the individual drugs in formulations.Keywords: Venlafaxine, Modafinil, Isocratic method, Validatio