Development and validation of spectrophotometric methods for estimation of antimigraine drug eletriptan hydrobromide...

The present study aims to develop and validate four simple, sensitive, reproducible, and low-cost spectrophotometric methods for the determination of antimigraine drug (eletriptan hydrobromide) in pure form and pharmaceutical formulations.

The methods are based on the formation of yellow colored ion-pair complex between eletriptan hydrobromide and four acid dyes, namely, bromocresol purple (BCP), bromocresol green (BCG), bromophenol blue (BPB), and bromothymol blue (BTB) with absorption maxima at 410, 420, 414 and 416nm, respectively. Several parameters such as pH, buffer type and volume, reagent volume, sequence of addition and effect of extracting solvent were optimized.

Under the optimum experimental conditions, beer's law is obeyed over the concentration ranges of 1.0-20 and 1.0-16μgmL^-1 for (BCP or BCG) and (BPB or BTB), respectively with good correlation coefficients (0.9995-0.9999). The apparent molar absorptivity and Sandell's sensitivity values are reported for all methods. The limit of detection (LOD) and the limit of quantification (LOQ) values are found to be 0.27, 0.28, 0.25, and 0.30μgmL^-1 and 0.90, 0.93, 0.83, and 1.0μgmL^-1 for BCP, BCG, BPB and BTB, respectively. The stoichiometric ratio of the formed ion-pair complexes was found to be 1:1 (drug: reagent) for all methods.

The developed methods were successfully applied for the determination of eletriptan hydrobromide in pharmaceutical formulations with good accuracy and precision. Statistical comparison of the results was performed using Student's t-test and variance ratio F-test at the 95% confidence level and there was no significant difference between the reported and proposed methods regarding accuracy and precision. Further, the validity of the proposed methods was confirmed by recovery studies via standard addition method.