International Interlaboratory Quality Control Program for Measurement of Antiretroviral Drugs in Plasma

An international interlaboratory quality control program for measurement of antiretroviral drugs was initiated. The first round was confined to protease inhibitors and showed large variability in the performance of participating laboratories. The results demonstrate the need for and utility of an ongoing quality control program in this area of bioanalysis

Determination of the HCV protease inhibitor telaprevir in plasma and dried blood spot by liquid chromatography-tandem mass spectrometry

Background: Telaprevir is a protease inhibitor used in the treatment of hepatitis C virus infection. Analytical methods for telaprevir should separate the compound from its R-diastereomer VRT-127394, which is 30-fold less active. The objective of this work was to develop liquid chromatography-tandem mass spectrometer (LC-MS/MS) assays for telaprevir both in plasma and in dried blood spot (DBS), capable of stabilizing the equilibrium and chromatographically separating the 2 epimers. Methods: Human plasma was acidified with formic acid and frozen within 1 hour after collection to stabilize the equilibrium between the 2 telaprevir diastereomers ex vivo in plasma. After protein precipitation, the sample was analyzed with LC-MS/MS. For the DBS assay, sampling paper was impregnated with citric acid solution to achieve stabilization of the epimers on the sampling paper. DBS samples were extracted before LC-MS/MS analysis. LC-MS/MS analysis comprised online solid-phase extraction and separation on a C18 column, with the mass spectrometer operating in TurboIonSpray-negative ionization mode and performing multiple reaction monitoring. Results: The assays were linear over the concentration range of 0.1-10 mg/L in plasma and DBS. Accuracies ranged from 97% to 106% in plasma and from 93% to 99% in DBS. Within- and between-day coefficients of variation wer

Drug-drug interactions between raltegravir and pravastatin in healthy volunteers.

Contains fulltext : 88810.pdf (publisher's version ) (Closed access)BACKGROUND: To evaluate the potential drug-drug interaction between raltegravir and pravastatin. METHODS: This was an open-label, randomized, 3-period, cross-over, single-centre trial in 24 healthy volunteers. Subjects received the following treatments: pravastatin 40 mg every day for 4 days, raltegravir 400 mg twice a day for 4 days, and pravastatin 40 mg every day + raltegravir 400 mg twice a day for 4 days. The treatments were separated by washout periods of 10 days. On day 4 of each treatment period, blood samples for pharmacokinetics were collected throughout a 24-hour period. RESULTS: Geometric mean ratios (90% confidence interval) for pravastatin + raltegravir versus pravastatin alone were 0.96 (0.83 to 1.11) for AUC0-24 and 1.04 (0.85 to 1.26) for Cmax. The mean low-density lipoprotein cholesterol decrease after 4 days of pravastatin was 0.42 mmol/L both in the presence and the absence of raltegravir. The geometric mean ratio (90% confidence interval) AUC0-12, Cmax, and C12 for raltegravir + pravastatin versus raltegravir alone were 1.13 (0.77 to 1.65), 1.31 (0.81 to 2.13), and 0.59 (0.39 to 0.88), respectively. CONCLUSIONS: Raltegravir did not influence the pharmacokinetics or the short-term lipid-lowering effects of pravastatin, whereas pravastatin increased the Cmax but decreased the C12 of raltegravir. The effects of pravastatin on raltegravir pharmacokinetics are not likely to be clinically relevant