Reversed phase-high performance liquid chromatographic method for simultaneous estimation of tolperisone hydrochloride and etodolac in a combined fixed dose oral formulations

A reversed-phase liquid chromatographic (RP-HPLC) method was developed for the simultaneous determination of tolperisone hydrochloride (TOLP) and etodolac (ETD) in a combined fixed dose oral formulation. The analysis was carried out using a phenomenax C-18, pre-packed column. A mobile phase containing a phosphate buffer (pH 5.5) : Methanol : Acetonitrile : Tri-ethylamine (40 : 40 : 20 : 1.5), with the pH adjusted to orthophosphoric acid, was pumped at a flow rate of 1.0 ml min(1) with a UV-detector and PDA detection at 257 nm. Retention time was 3.91 minutes and 6.89 minutes for TOLP and ETD, respectively. The method was validated for linearity, accuracy, precision, sensitivity, and specificity. The method showed good linearity in the range of 3 - 21 μg ml for TOLP μg / ml and 8 - 56 μg / ml for ETD. The detection limit of the proposed method was 0.16 μg / ml and 0.58 μg / ml for TOLP and ETD, respectively. The quantification limit of the proposed method was 0.51 μg / ml and 1.7 μg / ml for TOLP and ETD, respectively. The % recovery was within the range of 99.42 - 101.15 for TOLP and 98.63 - 100.94 for ETD. The percentage RSD for precision of the method was found to be less than 2%. The method was validated as per the International Conference on Harmonization (ICH) guidelines. The developed method could be applied for routine analysis of TOLP and ETD in tablet dosage form.