Stability Indicating Rp-Hplc and Hptlc Methods for the Estimation of Zolmitriptan.

The present studies is the stability-indicating RP-HPLC method for the determination of ZMT in the presence of degradation products was developed. ZMT was completely resolved from degradation products and impurities in a C-18 column (250 X 4.0 mm id, 5 μm particle size) using phosphate buffer (pH 3.5) and acetonitrile: methanol (50:50) as mobile phase (85:15) with a flow rate of 1 ml/ min and detected at a wavelength of 226 nm. A Phenomenex C-18 column was chosen because it has high carbon loading with very closely packed material to give high resolution compared to other C-18 column to develop a specific, accurate, precise and stability indicating RP-HPLC method for the estimation of ZMT. Different mobile phase systems were attempted to detect and quantify ZMT and its degradation product. The results of optimised mobile phase system (consisted of solvent A, phosphate buffer (pH 3.5), solvent B, acetonitrile: methanol (50:50) in the ratio of 85:15) was found to be satisfactory with respect to location and resolution of the peaks. The observed retention time for ZMT was found to be 9.2 min. The mobile phase saturation time was given about 15 min. Regression analysis of the calibration data for ZMT showed that the dependent variable (peak area) and the independent variable (concentration) were represented by the equation Y=14033x + (-1339). The correlation of coefficient (R2) obtained for ZMT was 0.9990. Thus a good linear relationship was observed in the concentration range of 2 – 10 μg/ml for ZMT. The assay of ZMT was found to be 99.42, which indicated high accuracy of the method. The absence of additional peaks in chromatogram indicated the non- interference of impurities. The method was designed to validate the stability-indicating RP- HPLC and HPTLC method for the determination of ZMT in bulk drug. The methods were validated by determining system suitability, specificity, precision, linearity, accuracy, stability, LOD, LOQ ruggedness and robustness parameters and found to be satisfactory. The stability indicating features of the methods were demonstrated by the forced degradation of the active ingredient by acid hydrolysis, base hydrolysis, oxidative degradation, dry heat degradation and photolysis. Forced degradants were shown to be non-interfering with the Rf value and Retention time of active ZMT. This reveals that the method is specific and selective. The standard preparations in the range of 2 μg/ml to 10 μg/ml of the assay concentration were linear (Correlation coefficient, R2 =0.999, n = 6) in the developed RP-HPLC method. The standard preparations in the range of 200 ng/spot to 1000 ng/spot of the assay standard concentration were linear (Correlation coefficient, R2 = 0.9989, n=6) in the developed HPTLC method. The ruggedness of both the RP-HPLC and HPTLC method demonstrated that different operational and environmental variables had only a minimal influence on the test results. It can be concluded that there is no other co eluting peak with the main peaks and hence both the RP-HPLC and HPTLC methods are specific for the estimation of ZMT in the presence of degradation products. Although no attempt was made to identify the degradation products, the described method can be used as stability indicating method for the assay of ZMT in bulk drug form. The method was completely validated showing satisfactory data for all the method validation parameters that were tested. The method can be employed as a stability indicating one, as the described method is capable of separating the drug from its degradation products. It was concluded that, the developed RP-HPLC and HPTLC method is specific, accurate, precise, linear, and it may be used for the routine application for the determination of ZMT in the bulk drug forms in the presence of their degradation products