Simultaneous determination of five HIV protease inhibitors nelfinavir, indinavir, ritonavir, saquinavir and amprenavir in human plasma by LC/MS/MS

Subnanogram on-line column-switching liquid chromatographic–tandem mass spectrometric quantification method for nelfinavir and methoxyphenol metabolite M1 in rat plasma

A new on-line, rapid and sensitive column-switch LC/MS/MS method to measure nelfinavir (NFV), an HIV-1 protease inhibitor, and its major metabolite (M1) in rat plasma was developed. Rat plasma containing the analytes and the internal standard was treated with acetonitrile and the supernatant was processed through an on-line extraction and an analytical columns, with a column-switch device. ESI-LC/MS with multiple reaction monitors for appropriate analytes was performed. This assay gave a limit of quantitation (LOQ) of <1 ng/mL for the analytes with 5 min run time. The within-run and between-run precisions were <12 and <10%, respectively. This analytical method was successfully applied to a study to correlate changes in maternal and placental NFV plasma concentrations in rats following NFV exposure in utero.

The ICH guidance in practice: stress degradation studies on indinavir sulphate and development of a validated specific stability-indicating HPTLC assay method

A sensitive, selective, precise and stability-indicating high-performance thin layer chromatography (HPTLC) method for analysis of indinavir sulphate both as a bulk drug and in formulations was developed and validated. The method employed TLC aluminium plates precoated with silica gel 60F-254 as the stationary phase. The solvent system consisted of carbon tetrachloride/chloroform/methanol/10% v/v ammonia (4:4.5:1.5:0.05, v/v/v/v). Densitometric analysis of indinavir sulphate was carried out in the absorbance mode at 260 nm. This system was found to give compact spots for indinavir sulphate (Rf value of 0.43 +/- 0.02, for six replicates). Indinavir sulphate was subjected to acid and alkali hydrolysis, oxidation, dry and wet heat treatment, and photo degradation. The drug undergoes degradation under acidic and basic conditions, oxidation, dry and wet heat treatment, and photo degradation. Also the degraded products were well resolved from the pure drug with significantly different Rf values. The method was validated for linearity, precision, robustness, limit of detection (LOD), limit of quantitation (LOQ), specificity and accuracy. Linearity was found to be in the range of 100-6000 ng/spot with significantly high value of correlation coefficient r2 = 0.997 +/- 0.64. The linear regression analysis data for the calibration plots showed good linear relationship with r2 = 0.999 +/- 0.002 in the working concentration range of 1000-6000 ng/spot. The LOD and LOQ were 40 and 120 ng/spot, respectively. Statistical analysis proves that the method is repeatable and specific for the estimation of the said drug. As the method could effectively separate the drug from its degradation products, it can be employed as a stability-indicating one. Moreover, the proposed HPTLC method was utilized to investigate the kinetics of acid degradation process. Arrhenius plot was constructed and activation energy was calculated.

High-performance liquid chromatography assay for the quantification of HIV protease inhibitors and non-nucleoside reverse transcriptase inhibitors in human plasma

An accurate, sensitive, and specific reverse-phase high-performance liquid chromatography (HPLC) assay for the simultaneous quantitative determination of HIV-protease inhibitors (PIs) (indinavir, IDV; amprenavir, APV; saquinavir, SQV; nelfinavir, NFV; ritonavir, RTV; and lopinavir, LPV) and non-nucleoside reverse transcriptase inhibitors (NNRTIs) (nevirapine, NVP; delavirdine, DLV; and efavirenz, EFV) in human blood plasma is described. The method provides excellent resolution and peak shape for nine analytes through a linear gradient (36-86%) of 25% phosphate buffer (pH 4.5), 60% acetonitrile, 15% methanol, and 0.75 ml TFA, with a gradient mobile phase flow rate (0.9-1.1 ml) over 30 min run time. The optimized solid phase extraction (SPE) extraction method using (1.0 ml, 100mg BOND ELUT-C18 Varian) column provides a clean base line and high extraction efficiency using a 550 microl plasma sample. The method was validated over the range of 10-10,000 ng/ml for NVP, IDV, and SQV; 10-5000 ng/ml for EFV; 25-10000 ng/ml for APV; and 25-5000 ng/ml for DLV, NFV, RTV, and LPV. This method is accurate (average accuracies of three different concentrations ranged from 91 to 112%), and precise (within- and between-day precision measures ranged from 0.2 to 5.7% and 0.1 to 5.4%, respectively). This method is suitable for use in clinical pharmacokinetic studies as well as in therapeutic drug monitoring (TDM).

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

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 75microm i.d. uncoated fused-silica capillary with 27cm length (effective length of 19.4cm) using a 20mmoll-1 phosphate buffer at pH 2.52. Samples were injected hydrodynamically by applying 0.5psi pressure during 2s. The applied voltage was 28kV. Direct UV detection at 214nm 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 1.66min, respectively. Analytical curve of peak area ratios versus concentration in the range of 20.0-100.0microg/ml gave a coefficient of correlation of 0.9992, establishing the method linearity. The limits of detection and quantitation were 4.61 and 14.0microg/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.