Development and Validation of RP-HPLC Method for the Simultaneous Estimation of Gabapentin and Nortriptyline Hydrochloride in Bulk and Tablet Dosage Form

Background: According to ICH requirements, a simple isocratic RP-HPLC technique for the simultaneous estimation of gabapentin (GAB) and nortriptyline HCl (NOR) in pharmaceutical dosage forms has been developed and validated. Methods: On a reversed phase, separation is accomplished Phenomenex Luna C-18 Column (5 mu m, 250 x 4.60 mm) as a stationary phase using two solvents (Solvent A: buffer 0.2 % Triethylamine adjusted to pH 5.5 with orthophosphoric acid and Solvent B: Acetonitrile) as a mobile phase. The ratio of Solvent A: Solvent B was 50:50 v/v. The flow rate was 1.2 ml/min with UV detection at 210 nm. Results: The retention time for Gabapentin and Nortriptyline HCl was found to be 1.96 and 4.54 min respectively with runtime of 15 min, theoretical plate for GAB and NOR were 3936 and 3912 respectively, with a resolution of 8.5. Linearity of GAB and NOR was found in the range of 200-1000 mu g/ml and 5-25 mu g/ml. The correlation coefficient for GAB and NOR were 0.9995 and 0.9998. The LOD values for GAB and NOR were 62.729 and 0.8727 mu g/ml. The LOQ values for GAB and NOR were 190.09 and 2.6447 mu g/ml respectively. The percentage of GAB and NOR in pharmaceutical dosage form was found to be 99.79 % and 99.75 %. Conclusion: This demonstrates that the developed method is simple, precise, rapid, selective, accurate and reproducible for simultaneous estimation of GAB and NOR tablet dosage form.