Capillary electrophoretic method for determination of protease inhibitor indinavir sulfate used in human immunodeficiency virus therapy

Abstract

A simple, fast and reliable capillary electrophoresis (CE) method for determination of indinavir sulfate, a potent protease inhibitor used in human immunodeficiency virus (HIV) therapy, in commercial and simulated capsule formulations is described. The analysis was performed in a 75 μm i.d. uncoated fused-silica capillary with 27 cm length (effective length of 19.4 cm) using a 20 mmol l −1 phosphate buffer at pH 2.52. Samples were injected hydrodynamically by applying 0.5 psi pressure during 2 s. The applied voltage was 28 kV. Direct UV detection at 214 nm led to an adequate sensitivity without interference from sample excipients and known impurities. For quantitative purposes, diazepam was used as internal standard. Under optimized conditions, the migration times for indinavir sulfate and diazepam were 1.06 and 1.66 min, respectively. Analytical curve of peak area ratios versus concentration in the range of 20.0–100.0 μg/ml gave a coefficient of correlation of 0.9992, establishing the method linearity. The limits of detection and quantitation were 4.61 and 14.0 μg/ml, respectively. The within-day precision expressed as relative standard deviation was <1.5% for 10 consecutive sample injections. An average recovery of 100.81±0.56% at three concentration levels was obtained. Based on the performance characteristics, the proposed methodology was found suitable for the determination of indinavir sulfate in capsule formulations, presenting additional advantages inherent to the CE technology, such as low consumption of reagents and column endurance.