Pharmacokinetic Interactions Between the Fixed-Dose Combinations of Elvitegravir/Cobicistat/Tenofovir Disoproxil Fumarate/Emtricitabine and Elbasvir/Grazoprevir in Healthy Adult Participants.

Treatment of individuals coinfected with human immunodeficiency virus (HIV) and hepatitis C virus (HCV) requires careful consideration of potential drug-drug interactions. The pharmacokinetic interaction of the HCV fixed-dose combination treatment of elbasvir/grazoprevir (EBR/GZR) when coadministered with the fixed-dose combination HIV treatment of elvitegravir/cobicistat/tenofovir disoproxil fumarate/emtricitabine (EVG/COB/TDF/FTC) was evaluated in 22 healthy adults. In period 1, oral doses of EVG/COB/TDF/FTC (150 mg/150 mg/300 mg/200 mg) were administered once daily for 7 days. In period 2, oral doses of EBR/GZR (50 mg/100 mg) were administered once daily for 10 days. In period 3, oral doses of EVG/COB/TDF/FTC were coadministered with EBR/GZR once daily for 10 days. The pharmacokinetics of EVG/COB/TDF/FTC were not clinically meaningfully altered by concomitant EBR/GZR administration. Geometric mean ratios (90%CIs) for area under the plasma concentration-time curve from time 0 to 24 hours (AUC0-24 ) in the presence/absence of EBR/GZR were 1.1 (1.0, 1.2) for elvitegravir; 1.1 (1.0, 1.1) for emtricitabine; 1.2 (1.1, 1.2) for tenofovir; and 1.5 (1.4, 1.6) for cobicistat. In comparison, the AUC0-24 of elbasvir was ∼2 times higher and the AUC0-24 of grazoprevir was ∼5 times higher following concomitant administration of EVG/COB/TDF/FTC and EBR/GZR. Geometric mean ratios (90%CI) for AUC0-24 in the presence/absence of EVG/COB/TDF/FTC were 2.2 (2.0, 2.4) for elbasvir and 5.4 (4.5, 6.4) for grazoprevir. Coadministration of EVG/COB/TDF/FTC and EBR/GZR was generally well tolerated in healthy adults in this study. Nevertheless, because of the increased GZR exposure that occurs with coadministration of EVG/COB/TDF/FTC and EBR/GZR, coadministration of this combination is not recommended in those coinfected with HIV and HCV.

Implementation of high-temperature superficially porous technologies for rapid LC-MS/MS diastereomer bioanalysis.

BACKGROUND: The fast-paced nature of the pharmaceutical industry requires robust bioanalytical methods to endure the high-throughput sample demands of the production environment. RESULTS: A rapid, accurate and precise LC-MS/MS method was developed for the quantitation of a diastereomer quartet in human plasma. Virtually all of the phosphatidylcholine and most of the lysophosphatidylcholine from human plasma were removed using a phospholipid-removing protein precipitation 96-well plate. An Agilent Poroshell SB-C18 2.1 × 50 mm superficially porous column was used at 100°C and 1.2 ml/min to separate a diastereomer quartet in <2.5 min. Peak shape, retention and resolution were maintained over nearly 200 extracted bioanalytical samples under these separation conditions. The method was tested for accuracy and precision; the assay inter-run accuracy and precision were minus 7.2-0.7% and 2.1-11.9%, respectively (n = 18). CONCLUSION: The application of the superficially porous column resulted in twofold response increase and a 2.6-fold reduction in cycle time compared with a 3.5-µm column performing under comparable resolution conditions.

Using temperature to optimize resolution and reduce analysis times for bioanalytical diastereomer LC-MS/MS separations.

A rugged and reproducible liquid chromatographic tandem mass spectrometric bioanalytical method was developed for the quantitation of drug stereoisomers in human plasma. Column temperature was shown to be an important variable toward optimizing diastereomer selectivity, resolution and analysis cycle time. Non-linear Van't Hoff plots and changes in peak shape with temperature suggested that selectivity was governed by multiple retention mechanisms. The high temperature chromatography method was validated and used to analyze samples from human clinical trials. Utilization of high temperature chromatography offered alternative selectivity and is a viable approach for difficult separations in regulated bioanalysis.

Stereoselective quantitation of a serine protease inhibitor using LC-MS/MS at elevated column temperature.

A LC-MS/MS method using a LC column packed with sub-2 micron particles and elevated column temperatures was validated for the quantitation of SCH 503034 diastereomers (SCH 534128 and SCH 534129) in human plasma. The method was validated over the concentration range of 2.5 to 1250 ng/mL. Inter-assay precision, based on percent relative deviation for n = 18 replicate quality controls, was 4.5% for SCH 534128 and 4.9% for SCH 534129. Inter-assay accuracy based on n = 18 replicate quality controls was +/- 7.8% for both SCH 534128 and SCH 534129. The method involved the novel application of ion pairing reagents to increase the stereoselectivity of the separation. Temperature, types of ion pairing reagent, and concentration of ion pairing reagent were all found to play significant roles in the resolution of the SCH 534128 and SCH 534129 diastereomers on a LC column packed with sub-2 micron particles. Specifically, a sensitivity increase of five-fold was demonstrated by increasing the column temperature. Without sacrificing resolution, the run time was significantly shortened when the column temperature was elevated to 100 degrees C.