45 ��m filter to obtain a clear filtrate. This solution was suitably diluted and used for analysis. After setting the chromatographic conditions and stabilizing the instrument to obtain selleck products a steady baseline, a fixed volume of 20 ��L of the sample solution was loaded by an automatic sampler. The solution was injected, and chromatograms were recorded. The injections were repeated six times, and the peak area were recorded. Validation procedure The method was validated for the parameters such as system suitability, specificity, linearity and range, accuracy, precision, ruggedness, and robustness.[14] The system suitability was assessed by five replicate analysis of the drug at a concentration as per standard preparation.

System suitability of the method was evaluated by analyzing the repeatability, peak symmetry (symmetry factor), theoretical plates of the column, resolution between the peaks, capacity factor, and relative retention. Specificity was also determined in the presence of excipients used in formulation, and chromatogram was observed and compared with that of a standard peak. To evaluate the linearity of the method, serial dilutions were made from a standard stock solution in the working range with the diluent which contains a mixture of methanol and sodium phosphate buffer dibasic (75:25) and resolved on a C8 column. To determine accuracy of the method in dosage formulation, a working standard of a drug was prepared. Samples for recovery studies were also prepared by spiking known amount of WS with placebo at three concentration levels (50%, 100%, and 150%) and analyzed.

The precision of the method was investigated with respect to repeatability. To determine intermediate precision, standard solutions of the drug at the 100% concentration level were analyzed three times within the same day (intra-day variation) and on three different days (inter-day variation). Robustness studies were performed on method precision by making slight variations in flow rate, amount of the mobile phase and pH changes. RESULTS AND DISCUSSION The goal of this study was to develop a rapid, easy accurate, precise, reliable and least time consuming HPLC method AV-951 for the analysis of doxofylline and montelukast sodium from the combined pharmaceutical formulation. The newly developed method has been validated as per guidelines of the International Conference on the Harmonization of Technical requirements for the Registration of pharmaceutical for Human use [ICH 2005] and has recommended the accomplishment of specificity, linearity, precision, accuracy, ruggedness, and robustness of the method. System suitability testing Typical system suitability results were summarized in Table 1. All the values for the system suitability parameters were within limits.