Stability-indicating HPLC determination of tolterodine tartrate in pharmaceutical dosage form

A simple, selective, precise and stability-indicating high-performance liquid chromatographic (HPLC) method of analysis tolterodine tartrate in pharmaceutical dosage form was developed and validated. The chromatographic conditions comprised a reversed-phase C18 column (250 × 4.6 mm), 5 μ with a mobile phase consisting of a mixture of buffer solution (2.88 g ammonium dihydrogen orthophosphate in 1 L of water) and methanol in the ratio of 40 : 60. Triethylamine (5 mL /L) was added to it and pH of mobile phase was adjusted to 7.0± 0.1 with orthophosphoric acid at a flow rate of 1.5 mL/min. Detection was carried out at 220 nm. The retention time of tolterodine was 6.49 min. The linear regression analysis data for the calibration plots showed good linear relationship with coefficient of regression value, r = 0.99 in the concentration range 200.60-601.80 μg per mL. The value of correlation coefficient, slope and intercept were 1.0, 20.87 and –6.87, respectively. The method was validated for precision, recovery, ruggedness and robustness. The drug undergoes degradation under acidic, basic, photochemical and thermal conditions. All the peaks of degraded product were resolved from the active pharmaceutical ingredient with significantly different retention time. The samples degraded with hydrogen peroxide showed no additional peak. This indicates that the drug is susceptible to acid-base hydrolysis, photochemical and thermal degradation. Statistical analysis proves that the method is reproducible and selective for the estimation of said drug. As the method could effectively separate the drug from its degradation product, it can be employed as a stability-indicating one.