Extractive Spectrophotometric Methods for Determination of Pramipexole Dihydrochloride in Pharmaceutical Preparations through Ion-Pair Technique

摘要

Simple, sensitive, precise, reproducible and validated visible spectrophotometric methods have been developed for the determination of antiparkinson agent, pramipexole dihydrochloride monohydrate (PRM) in pure form and pharmaceutical preparations. The proposed spectrophotometric methods are based on the formation of yellow colored ion-pair complexes between PRM, and three dyes, bromocresol purple (BCP), bromophenol blue (BPB and) methyl orange (MO) with absorption maxima at 410, 416 and 421 nm, respectively. Several parameters such as pH, buffer type, reagent volume, sequence of addition and effect of extracting solvent were optimized to achieve high sensitivity, stability, low blank reading and reproducible results. Under the optimum reaction conditions, linear relationships were found between the absorbance's over the concentration ranges of 2.0–12, 1.0-10 and 2.0–16 μg ml-1 with good correlation coefficients ≥ 0.9992 and LOD of 0.58, 0.28 and 0.60 μg ml-1 and the calculated molar absorptivity values are 1.1737 × 104, 2.3043 × 104 and 1.2847 × 104 l mol-1 cm-1 using BCP, BPB and MO methods, respectively. The stoichiometric ratio of the formed ion-pair complexes was found to be 1:1 (drug: reagent) for all methods as deduced by Job's method of continuous variation. Various analytical parameters have been evaluated and the results have been validated by statistical data. The proposed methods were validated in accordance with ICH guidelines and successfully applied to the analysis of PRM in pharmaceutical preparations (tablets). Statistical comparison of the results obtained by applying the proposed methods with those of the official method revealed good agreement and proved that there was no significant difference in the accuracy and precision between the results. The reliability of the methods was further ascertained by performing recovery studies using the standard addition method.