Stability-Indicating HPLC Determination of Rifampicin in Bulk Drug and Dosage Form

Abstract

A simple, selective, precise and stability-indicating high-performance liquid chromatography (HPLC) method for the determination of rifampicin in the parent drug substance and drug products was developed and validated as per the current ICH guidelines. The analysis was achieved isocratically on Phenomenex Luna C₁₈ column (5 μm; 250 × 4.6 mm) utilizing a mobile phase consisting of a mixture of formic acid buffer, pH adjusted to 4.5, and acetonitrile (55:45 v/v) at a flow rate of 1.5 mL min^-1 with UV detection at 235 nm. The retention time was 3.5 min. The linear regression analysis for calibration plot showed good linear relationship with r₂ = 0.9999 with respect to peak area in the concentration range 5 – 250 μg mL^-1. The limits of detection and quantification were 3.0 and 9.2 μg mL^-1, respectively. The method was validated for precision, accuracy, selectivity, recovery, robustness and ruggedness. The intra-day and inter-day accuracy expressed as % relative error were better than 2%. The precision determined and expressed as % relative standard deviation did not exceed 0.5%. Rifampicin was subjected to acid and alkali hydrolysis, oxidation, photo degradation and dry heat treatment. The drug was found to undergo complete degradation under acid-, base-, and oxidation-induced stress conditions, but was stable under other stress conditions. The method was applied to commercial drug capsules and showed highly satisfactory results.