Derivative UV-Spectrophotometric Assay Methods for Determination of Ivacaftor

Ivacaftor is a selective small molecule potentiator Transmembrane Conductance Regulator protein used for the treatment of cystic fibrosis. This report describes the validation of simple, rapid, sensitive and cost-effective zeroorder and first-order derivative spectrophotometric methods for the estimation of ivacaftor in bulk and in its marketed formulation. Preliminary spectrophotometric analysis of the drug was carried out in methanol and a total of 21 parametric variations were considered. Three selected method variants employing absorbance (zero-order), peak-peak- to-peak (first-order), and peak-to-zero (second order) techniques were assessed for their stability indicating potential in stress degraded solutions of the drug. The developed method was validated with respect to parameters including linearity, accuracy, precision, robustness, and solution stability. Excellent linearity was observed in the concentration range of 5.0–30.0 μg/mL with a correlation coefficient of 0.99 and above for the selected method variants. The limits of assay detection values ranged from 0.90–1.06 μg/mL, and quantitation limits ranged from 2.72–3.22 μg/mL for the proposed method variants. The proposed methods were used to quantify the drug in its marketed tablet formulation, and good recoveries ranging from 95.98 to 98.81% were obtained.