A novel LC-MS/MS method for the determination of favipiravir ribofuranosyl-5'-triphosphate (T-705-RTP) in human peripheral mononuclear cells.

Favipiravir is a broad-spectrum antiviral that is metabolised intracellularly into the active form, favipiravir ribofuranosyl-5'-triphosphate (F-RTP). Measurement of the intracellular concentration of F-RTP in mononuclear cells is a crucial step to characterising the pharmacokinetics of F-RTP and to enable more appropriate dose selection for the treatment of COVID-19 and emerging infectious diseases. The described method was validated over the range 24 - 2280 pmol/sample. Peripheral blood mononuclear cells (PBMCs) were isolated from whole blood and lysed using methanol-water (70:30, v/v) before cellular components were precipitated with acetonitrile and the supernatant further cleaned by weak anion exchange solid phase extraction. The method was found to be both precise and accurate and was successfully utilised to analyse F-RTP concentrations in patient samples collected as part of the AGILE CST-6 clinical trial.

Development and validation of an LC-MS/MS method for quantification of favipiravir in human plasma.

Favipiravir (FVP) is a broad-spectrum antiviral that selectively inhibits viral RNA-dependent RNA polymerase, first trialled for the treatment of influenza infection. It has been shown to be effective against a number of RNA virus families including arenaviruses, flaviviruses and enteroviruses. Most recently, FVP has been investigated as a potential therapeutic for severe acute respiratory syndrome coronavirus 2 infection. A liquid chromatography tandem mass spectrometry method for the quantification of FVP in human plasma has been developed and validated for use in clinical trials investigating favipiravir as treatment for coronavirus disease-2019. Samples were extracted by protein precipitation using acetonitrile, using 13C, 15N- Favipiravir as internal standard. Elution was performed on a Synergi Polar-RP 150 × 2.1 mm 4 µm column using a gradient mobile phase programme consisting of 0.2% formic acid in water and 0.2% formic acid in methanol. The assay was validated over the range 500-50,000 ng/mL; this method was found to be precise and accurate and recovery of FVP from the matrix was high. Stability experiments confirmed and expanded on the known stability of FVP, including under heat treatment and for a period of 10 months at - 80 °C.

Pharmacokinetic/pharmacodynamic investigation of raltegravir with or without lamivudine in the context of HIV-1 pre-exposure prophylaxis (PrEP).

BACKGROUND: To characterize their potential use in pre-exposure prophylaxis (PrEP) we compared the pharmacokinetics of raltegravir and lamivudine in genital tissue against ex vivo tissue infection with HIV-1. METHODS: Open-label trial of 36 HIV-negative females and males randomized to 7 days raltegravir 400 mg twice daily and 7 days raltegravir 400 mg+lamivudine 150 mg twice daily (after washout), or vice versa. Blood, saliva, rectal fluid, rectal tissue, vaginal fluid and vaginal tissue were sampled at baseline and on and off PrEP during a total of 12 days, for pharmacokinetics and antiviral activity via ex vivo HIV-1BaL challenge. Ex vivo infectivity was compared with baseline. The trial has been registered in https://clinicaltrials.gov/ with the identifier NCT03205566. RESULTS: Steady state for both drugs was reached by day 4. Dosing with raltegravir alone provided modest ex vivo HIV protection with higher drug levels in rectal tissue and vaginal tissue than in plasma on and off PrEP. Off PrEP, plasma and vaginal concentrations declined rapidly, while persisting in the rectum. On PrEP, the highest lamivudine concentrations were in the rectum, followed by vaginal tissue then plasma. Lamivudine washout was rapid in plasma, while persisting in the rectum and vagina. Raltegravir/lamivudine increased ex vivo protection on and off PrEP compared with raltegravir alone, reaching maximum protection at day 2 in rectal tissue and at day 8 in vaginal tissue. CONCLUSIONS: Raltegravir 400 mg+lamivudine 150 mg showed high levels of ex vivo HIV protection, associated with high drug concentrations persisting after discontinuation in vaginal and rectal compartments, supporting further investigation of these agents for PrEP.

The development and validation of a novel LC-MS/MS method for the quantification of cenicriviroc in human plasma and cerebrospinal fluid.

A high-performance liquid chromatography tandem mass spectrometric method was developed and validated for cenicriviroc (CVC) quantification in human plasma and cerebrospinal fluid (CSF). The method involved precipitation with acetonitrile and injecting supernatants onto the column. Separation was achieved on an XBridge C18 column with a gradient elution of 0.1% formic acid in water and acetonitrile. Analyte detection was conducted in positive ion mode using selected reaction monitoring. The m/z transitions were: CVC (697.3 → 574.3) and CVC-d7 (704.4 → 574.3). Calibration curve ranged from 5 to 1000 ng/mL for plasma and from 0.241 to 15.0 ng/mL for CSF. The intra- and inter-day precision and accuracy were <15% for both plasma and CSF across four different concentrations. CVC recovery from plasma and artificial CSF was >90%. The method was utilized for the measurement of patients' plasma and CSF samples taking a dose of 50, 150 and 300 mg q.d.

Pharmacokinetics of dolutegravir with and without darunavir/cobicistat in healthy volunteers.

Background: Dolutegravir combined with darunavir/cobicistat is a promising NRTI-sparing and/or salvage strategy for the treatment of HIV-1 infection. Methods: This Phase I, open-label, 57 day, crossover, pharmacokinetic (PK) study, enrolled healthy volunteers aged 18-65 years, who were randomized to one of two groups. Group 1 received dolutegravir (50 mg) once daily for 14 days followed by a 7 day washout, then a 14 day dolutegravir/darunavir/cobicistat (DTG/DRV/COBI) once-daily co-administration period followed by a 7 day washout and finally a 14 day period of darunavir/cobicistat (800/150 mg) once daily. Group 2 followed the same sequence starting with darunavir/cobicistat and concluding with dolutegravir. Each group underwent intensive PK sampling over 24 h on day 14 of each drug period and DTG/DRV/COBI concentrations were measured using validated LC-MS/MS methods. Results: Twenty participants completed all PK phases. Thirteen were female and median age and BMI were 33.5 years and 27 kg/m2. Dolutegravir geometric mean ratios (GMR, DTG/DRV/COBI versus dolutegravir alone) and 90% CI for Cmax, AUC0-24 and C24 were 1.01 (0.92-1.11), 0.95 (0.87-1.04) and 0.9 (0.8-1.0), respectively. Darunavir GMR (DRV/COBI/DTG versus darunavir/cobicistat alone) and 90% CI for Cmax, AUC0-24 and C24 were 0.90 (0.83-0.98), 0.93 (0.86-1.00) and 0.93 (0.78-1.11), respectively. No grade 3 or 4 adverse events or laboratory abnormalities were observed. Conclusions: Concentrations of dolutegravir and darunavir, when boosted with cobicistat, decreased by <10% during co-administration, suggesting this combination can be prescribed safely in the treatment of HIV-1, with no adjustment to current guideline-recommended dosages.

Validation and clinical application of a novel LC-MS method for quantification of dolutegravir in breast milk.

Aim: A novel, sensitive and reproducible method for quantification of dolutegravir (DTG) in dried breast milk spots (DBMS) was developed and validated for use in clinical studies. Its application enabled measurement of DTG pharmacokinetics in breastfeeding mothers and their infants. Results/methodology: Sample extraction was by liquid-liquid extraction using tert-butyl methy-ether, with DTG-d5 as an internal standard. DTG was eluted on a reverse phase C18 Waters XBridge (3.5 µm: 2.1 × 50 mm) column using a gradient mobile phase consisting of 0.1% formic acid in deionised water or methanol. The assay was validated over a calibration range of 10-4000 ng/ml. Conclusion: Stability, inter and intra-assay variability were acceptable according to FDA and EMA bioanalytical method guidelines. The assay is robust, accurate, precise and can be reliably applied for analysis of clinical samples in trials from low resource settings.

Pharmacokinetics of darunavir/cobicistat and etravirine alone and co-administered in HIV-infected patients.

Objectives: To determine the effect of etravirine on the pharmacokinetics of darunavir/cobicistat and vice versa. Safety and tolerability of this combination were also evaluated. Methods: Open-label, fixed-sequence trial in two cohorts of HIV-infected patients on therapy with darunavir/cobicistat 800/150 mg once daily (DRV cohort; n = 15) or etravirine 400 mg once daily (ETR cohort; n = 15). Etravirine or darunavir/cobicistat were added on days 1-14 and 1-7 in participants in the DRV or ETR cohort, respectively. Full pharmacokinetic profiles were obtained on days 0 and 14 in the DRV cohort, and on days 0 and 7 in the ETR cohort. Darunavir, cobicistat and etravirine pharmacokinetic parameters [AUC0-24, Cmax and trough concentrations in plasma (C24)] were calculated for each individual by non-compartmental analysis and were compared using linear mixed-effects models. Adverse events and HIV-1 RNA in plasma were monitored. Results: Etravirine co-administration decreased cobicistat AUC0-24, Cmax and C24 by 30%, 14% and 66%, respectively. Although darunavir AUC0-24 and Cmax were unchanged by etravirine, darunavir C24 was 56% lower for darunavir/cobicistat co-administered with etravirine relative to darunavir/cobicistat alone. Etravirine pharmacokinetics were unchanged by darunavir/cobicistat. Treatments were well tolerated, and HIV-1 RNA remained undetectable in all participants. Conclusions: Although etravirine pharmacokinetics was unchanged by darunavir/cobicistat, there was a significant decrease in cobicistat exposure and in darunavir C24 when darunavir/cobicistat was co-administered with etravirine. Boosting darunavir with ritonavir instead of with cobicistat may be preferred if darunavir is to be combined with etravirine in clinical practice.

The development and application of a novel LC-MS/MS method for the measurement of Dolutegravir, Elvitegravir and Cobicistat in human plasma.

Dolutegravir and Elvitegravir belongs to a class of integrase inhibitors which has recently been approved by the FDA for the treatment of HIV-infection. Elvitegravir and its co-administered booster drug, Cobicistat, has shown the potential to be a candidate for a one pill once a day regimen and is currently a component of many clinical trials. A sensitive LC-MS/MS method has been developed and validated for the simultaneous determination of these three drugs in human plasma. A liquid- liquid extraction was used as a sample preparation technique using 100µL of plasma. The method was validated from 10 to 4000ng/mL for Dolutegravir, Elvitegravir and Cobicistat. Chromatography was performed on XBridge C18 2.1mm×50mm column, using an 80:20 methanol/water mobile phase containing 0.1% formic acid on a gradient program. This method was successfully applied for ongoing clinical trials.