Validation of an LC-MS/MS assay for the simultaneous determination of bictegravir, doravirine, and raltegravir in human plasma.

Bictegravir (BIC), an integrase inhibitor, and doravirine (DOR), a non-nucleoside reverse transcriptase inhibitor, were recently approved by the US FDA for HIV treatment and are recommended first line treatment options. Because certain clinical scenarios warrant using them in combination, we developed a fully validated LC-MS/MS method for simultaneous measurement of BIC and DOR, along with a legacy integrase inhibitor, raltegravir (RAL), in human plasma over a clinically relevant 1000-fold range for each analyte. These analytes were extracted from the plasma by protein precipitation with their stable, isotopically labeled internal standards (BIC-d5, 13C6-DOR, and RAL-d6). Following extraction, samples were analyzed by reverse phase chromatography on a Waters Atlantis T3 C18 (50 ×2.1 mm, 3 µm particle size) column with subsequent detection by electrospray ionization in positive ion mode on an AB Sciex API-5000 triple quadrupole mass spectrometer. The assay was linear (R2 >0.994) over the selected calibration ranges (20.0-20,000 ng/mL (BIC), 3.00-3000 ng/mL (DOR), and 10.0-10,000 (RAL)). The assay was accurate (inter-assay %Bias ≤ ± 8.5) and precise (inter-assay %CV ≤11.4). This method was validated according to FDA guidance for industry and can be used to assess the pharmacokinetics of two newly approved antiretrovirals, or to support therapeutic drug monitoring for modern antiretroviral therapy.

A mechanism-based pharmacokinetic model of remdesivir leveraging interspecies scaling to simulate COVID-19 treatment in humans.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreak initiated the global coronavirus disease 2019 (COVID-19) pandemic resulting in 42.9 million confirmed infections and > 1.1 million deaths worldwide as of October 26, 2020. Remdesivir is a broad-spectrum nucleotide prodrug shown to be effective against enzootic coronaviruses. The pharmacokinetics (PKs) of remdesivir in plasma have recently been described. However, the distribution of its active metabolite nucleoside triphosphate (NTP) to the site of pulmonary infection is unknown in humans. Our objective was to use existing in vivo mouse PK data for remdesivir and its metabolites to develop a mechanism-based model to allometrically scale and simulate the human PK of remdesivir in plasma and NTP in lung homogenate. Remdesivir and GS-441524 concentrations in plasma and total phosphorylated nucleoside concentrations in lung homogenate from Ces1c-/- mice administered 25 or 50 mg/kg of remdesivir subcutaneously were simultaneously fit to estimate PK parameters. The mouse PK model was allometrically scaled to predict human PK parameters to simulate the clinically recommended 200 mg loading dose followed by 100 mg daily maintenance doses administered as 30-minute intravenous infusions. Simulations of unbound remdesivir concentrations in human plasma were below 2.48 µM, the 90% maximal inhibitory concentration for SARS-CoV-2 inhibition in vitro. Simulations of NTP in the lungs were below high efficacy in vitro thresholds. We have identified a need for alternative dosing strategies to achieve more efficacious concentrations of NTP in human lungs, perhaps by reformulating remdesivir for direct pulmonary delivery.

Disparate effects of cytotoxic chemotherapy on the antiviral activity of antiretroviral therapy: implications for treatments of HIV-infected cancer patients.

BACKGROUND: Cancer is a leading cause of death in HIV-infected patients in the era of combination antiretroviral therapy (cART). Yet, there are no specific guidelines for the combined use of cART and chemotherapy in HIV-infected cancer patients. The cellular enzyme thymidylate synthase (TS) catalyses the conversion of dUMP to TMP, which is converted to TDP and ultimately to TTP, a building block in DNA synthesis. TS inhibitors are recommended in some cancers, particularly non-small cell lung cancer (NSCLC). Because TS inhibitors modulate intracellular concentrations of endogenous 2'-deoxynucleotides, we hypothesized that TS inhibitors could impact the anti-HIV activity of nucleoside analogue reverse transcriptase inhibitors (NRTIs). METHODS: We evaluated gemcitabine and pemetrexed, two approved TS inhibitors, on the anti-HIV activities of NRTIs in infectivity assays using peripheral blood mononuclear cells (PBMCs) and in humanized mice. RESULTS: Gemcitabine enhanced the anti-HIV activities of tenofovir, abacavir and emtricitabine (FTC) in PBMCs. In contrast, pemetrexed had no effect on tenofovir, enhanced abacavir and, unexpectedly, decreased FTC and lamivudine (3TC) activities. Pemetrexed inhibitory effects on FTC and 3TC may be due to lower concentrations of active metabolites (FTCtp and 3TCtp) relative to their competing endogenous nucleotide (dCTP), as shown by decreases in FTCtp/dCTP ratios. Gemcitabine enhanced tenofovir while pemetrexed abrogated FTC antiviral activity in humanized mice. CONCLUSIONS: Chemotherapy with TS inhibitors can have opposing effects on cART, potentially impacting control of HIV and thereby development of viral resistance and size of the reservoir in HIV-infected cancer patients. Combinations of cART and chemotherapy should be carefully selected.

Smartphone-Based Contingency Management Intervention to Improve Pre-Exposure Prophylaxis Adherence: Pilot Trial.

BACKGROUND: Pre-exposure prophylaxis (PrEP) provides a strong preventative benefit to individuals at risk for HIV. While PrEP adherence is highly correlated with its efficacy, adherence rates are variable both across and within persons. OBJECTIVE: The objective of this study was to develop and pilot-test a smartphone-based intervention, known as mSMART, that targets PrEP adherence. mSMART provides contingency management in the form of monetary incentives for daily PrEP adherence based on a real-time adherence assessment using a camera-based medication event-monitoring tool as well as medication reminders, PrEP education, individualized behavioral strategies to address PrEP adherence barriers, and medication adherence feedback. METHODS: This was a 4-week open-label, phase I trial in a community sample of young men who have sex with men already on PrEP (N=10). RESULTS: Although adherence composite scores corresponding to PrEP biomarkers indicated that 90% (9/10) of the sample already had an acceptable baseline adherence in the protective range, by the end of the 4-week period, the scores improved for 30% (3/10) of the sample-adherence did not worsen for any participants. Participants reported mean PrEP adherence rates of 91% via daily entries in mSMART. At the end of the 4-week period, participants indicated acceptable ratings of satisfaction, usability, and willingness to recommend mSMART to others. There were no technical difficulties associated with smartphone compatibility, user misunderstandings about mSMART features that interfered with daily use, or study attrition. CONCLUSIONS: This study is the first to apply contingency management to PrEP adherence. Findings indicated that mSMART is feasible and acceptable. Such an adherence intervention administered via a user-friendly smartphone app can allow for widespread dissemination. Future efficacy trials are needed. TRIAL REGISTRATION: ClinicalTrials.gov NCT02895893; https://clinicaltrials.gov/ct2/show/NCT02895893 (Accessed by Webcite at http://www.webcitation.org/72JskjDJq).

Virological and immunological responses to raltegravir and dolutegravir in the gut-associated lymphoid tissue of HIV-infected men and women.

BACKGROUND: Raltegravir (RTG) and dolutegravir (DTG) have different pharmacokinetic patterns in the gastrointestinal tract. To determine if this results in pharmacodynamic differences, we compared HIV RNA, HIV DNA and immunological markers in gut-associated lymphoid tissue (GALT) of HIV-infected participants receiving RTG or DTG with tenofovir+emtricitabine (TDF/FTC). METHODS: GALT specimens from the terminal ileum, splenic flexure and rectum were obtained by colonoscopy at a single time point in 20 adults treated with RTG (n=10) or DTG (n=10) with HIV RNA <50 copies/ml. Flow cytometry, drug concentrations, and HIV RNA and DNA were analysed in tissue. CD4/8+ T-cells were tested for γδ TCR, and markers of T-cell activation and exhaustion. Data are reported as median (Q1-Q3). RESULTS: A total of 15 men and 5 women were enrolled. There was no difference in time since HIV diagnosis for those on RTG (9.5 [4-22] years) and DTG (17 [1-24] years; P=0.6), although time on RTG (5.4 [2.3-6.7] years) was greater than DTG (1.0 [0.1-1.5] years; P<0.001). Concentrations of RTG and DTG in rectal tissue were similar to previous reports: median tissue:plasma ratio was 11.25 for RTG and 0.44 for DTG. RNA:DNA ratios were 1.14 (0.18-5.10) for the RTG group and 0.90 (0.30-18.87) for the DTG group (P=0.95). No differences (P≥0.1) between CD4+ and CD8+ T-cell markers were found. CONCLUSIONS: RTG produced higher tissue exposures than DTG, but no significant differences in GALT HIV RNA, DNA or most immunological markers were observed. ClinicalTrials.gov NCT02218320.

Non-initiation of hepatitis C virus antiviral therapy in patients with human immunodeficiency virus/hepatitis C virus co-infection.

AIM: To assess whether reasons for hepatitis C virus (HCV) therapy non-initiation differentially affect racial and ethnic minorities with human immunodeficiency virus (HIV)/HCV co-infection. METHODS: Analysis included co-infected HCV treatment-naïve patients in the University of North Carolina CFAR HIV Clinical Cohort (January 1, 2004 and December 31, 2011). Medical records were abstracted to document non-modifiable medical (e.g., hepatic decompensation, advanced immunosuppression), potentially modifiable medical (e.g., substance abuse, severe depression, psychiatric illness), and non-medical (e.g., personal, social, and economic factors) reasons for non-initiation. Statistical differences in the prevalence of reasons for non-treatment between racial/ethnic groups were assessed using the two-tailed Fisher's exact test. Three separate regression models were fit for each reason category. Odds ratios and their 95%CIs (Wald's) were computed. RESULTS: One hundred and seventy-one patients with HIV/HCV co-infection within the cohort met study inclusion. The study sample was racially and ethnically diverse; most patients were African-American (74%), followed by Caucasian (19%), and Hispanic/other (7%). The median age was 46 years (interquartile range = 39-50) and most patients were male (74%). Among the 171 patients, reasons for non-treatment were common among all patients, regardless of race/ethnicity (50% with ≥ 1 non-modifiable medical reason, 66% with ≥ 1 potentially modifiable medical reason, and 66% with ≥ 1 non-medical reason). There were no significant differences by race/ethnicity. Compared to Caucasians, African-Americans did not have increased odds of non-modifiable [adjusted odds ratio (aOR) = 1.47, 95%CI: 0.57-3.80], potentially modifiable (aOR = 0.72, 95%CI: 0.25-2.09) or non-medical (aOR = 0.90, 95%CI: 0.32-2.52) reasons for non-initiation. CONCLUSION: Race/ethnicity alone is not predictive of reasons for HCV therapy non-initiation. Targeted interventions are needed to improve access to therapy for all co-infected patients, including minorities.

Antiretroviral activity and safety of once-daily etravirine in treatment-naive HIV-infected adults: 48-week results.

BACKGROUND: Etravirine (ETR), a non-nucleoside reverse transcriptase inhibitor approved for 200 mg twice-daily dosing in conjunction with other antiretrovirals (ARVs), has pharmacokinetic properties which support once-daily dosing. METHODS: In this single-arm, open-label study, 79 treatment-naive HIV-infected adults were assigned to receive ETR 400 mg plus tenofovir disoproxil fumarate/emtricitabine (TDF/FTC) 300/200 mg once daily to assess antiviral activity, safety and tolerability. ARV activity at 48 weeks was determined by proportion of subjects with HIV-1 RNA<50 copies/ml (intention-to-treat, missing = failure). RESULTS: Of 79 eligible subjects, 90% were men, 62% African-American and 29% Caucasian. At baseline, median (Q1, Q3) age was 29 years (23, 44) and HIV-1 RNA 4.52 log10 copies/ml (4.07, 5.04). A total of 69 (87%) completed a week 48 visit and 61 (77%, 95% CI 66%, 86%) achieved HIV-1 RNA<50 copies/ml at week 48. At time of virological failure, genotypic resistance-associated mutations were detected in three participants, two with E138K (one alone and one with additional mutations). Median (95% CI) CD4(+) cell count increase was 163 (136, 203) cells/µl. Fifteen (19.0%) participants reported a new sign/symptom or lab abnormality ≥ Grade 3 and three participants (3.8%) permanently discontinued ETR due to toxicity. Two participants had psychiatric symptoms of any grade. There were no deaths. CONCLUSIONS: In this study of ARV-naive HIV-positive adults, once-daily ETR with TDF/FTC had acceptable antiviral activity and was well-tolerated. Once-daily ETR may be a plausible option as part of a combination ARV regimen for treatment-naive individuals. ClinicalTrials.gov NCT00959894.

HIV PrEP Trials: The Road to Success.

The global HIV epidemic cannot be controlled by current treatment or prevention strategies. Pre-exposure prophylaxis (PrEP) using antiretrovirals is a promising approach to curbing the spread of HIV transmission. Recently, four clinical trials demonstrated favorable results when antiretroviral PrEP was administered topically or orally. However, two additional trials were unable to demonstrate a benefit, indicating that further study is required to define the populations and conditions under which PrEP will be effective. Adherence is highly correlated with protection, yet the exact level of adherence required is unknown. Future studies may require increased drug exposure testing and more objective methods to monitor adherence in real-time. Although the development of drug resistance in the PrEP trials has been low, it remains a concern, as therapeutic options could be compromised for those who seroconvert while on PrEP.

The warfarin-cranberry juice interaction revisited: A systematic in vitro-in vivo evaluation.

BACKGROUND: Cranberry products have been implicated in several case reports to enhance the anticoagulant effect of warfarin. The mechanism could involve inhibition of the hepatic CYP2C9-mediated metabolic clearance of warfarin by components in cranberry. Because dietary/natural substances vary substantially in bioactive ingredient composition, multiple cranberry products were evaluated in vitro before testing this hypothesis in vivo. METHODS: The inhibitory effects of five types of cranberry juices were compared with those of water on CYP2C9 activity (S-warfarin 7-hydroxylation) in human liver microsomes (HLM). The most potent juice was compared with water on S/R-warfarin pharmacokinetics in 16 healthy participants given a single dose of warfarin 10 mg. RESULTS: Only one juice inhibited S-warfarin 7-hydroxylation in HLM in a concentration-dependent manner (P < 0.05), from 20% to >95% at 0.05% to 0.5% juice (v/v), respectively. However, this juice had no effect on the geometric mean AUC(0-∞) and terminal half-life of S/R-warfarin in human subjects. CONCLUSIONS: A cranberry juice that inhibited warfarin metabolism in HLM had no effect on warfarin clearance in healthy participants. The lack of an in vitro-in vivo concordance likely reflects the fact that the site of warfarin metabolism (liver) is remote from the site of exposure to the inhibitory components in the cranberry juice (intestine).

Measurement of antiretroviral drugs in the lungs of HIV-infected patients.

AIMS: Prior studies have shown that HAART is associated with decreased HIV viral load in the lungs. The correlation between antiretroviral exposure in bronchoalveolar lavage (BAL) fluid and virologic response was evaluated in patients starting HAART and enrolled in The AIDS Clinical Trial Group Protocol 723. MATERIALS #ENTITYSTARTX00026; METHODS: A total of 24 subjects underwent blood and BAL sampling prior to starting HAART, and after 4 and 24 weeks of HAART. Drug concentrations and HIV RNA were measured in paired plasma and BAL samples. RESULTS: Antiretroviral drugs, including efavirenz, were detectable in BAL fluid of HIV-infected subjects beginning HAART. Efavirenz was also associated with a higher likelihood of clearing HIV RNA from the lungs. CONCLUSION: These results suggest the excellent pulmonary virologic response to antiretroviral therapy may, in part, be due to penetration of antiretroviral drugs into the alveolar compartment.

Pharmacokinetics of generic and trade formulations of lamivudine, stavudine and nevirapine in HIV-infected Malawian children.

BACKGROUND: The aim of this study was to evaluate the pharmacokinetics of lamivudine (3TC), stavudine (d4T) and nevirapine (NVP) in HIV-infected Malawian children receiving quartered tablet multiples of Triomune 40 (generic tablet [GT]) compared with individual generic liquid (GL) and trade liquid (TL). METHODS: This was a prospective randomized three-way crossover study. Patients (8-<12 kg, 18-<22 kg or 28-<32 kg body weight) taking Triomune 40 were recruited and randomized to receive GT twice daily (one-quarter, one-half or three-quarter tablets using Malawi treatment guidelines), GL twice daily (in the equivalent dose of GT) or TL twice daily (dosed using weight and age from US Department of Health and Human Services paediatric treatment guidelines). After 10 days of one formulation, 6-h pharmacokinetic sampling was performed, and patients were crossed over to subsequent formulations. Baseline concentration (C(0 h)), area under the curve (AUC)(0-6 h), maximum plasma concentration (C(max)) and time to C(max) were generated for each antiretroviral treatment. RESULTS: A total of 7 males and 11 females (6 in each GT dosing group) with a median (range) age of 7.2 years (1.3-13.6), weight of 19 kg (9.0-30.5) and height of 109 cm (75-132) were recruited. Combining all patients, no difference in pharmacokinetics was noted among the formulations for all drugs. However, patients in the one-quarter GT dosing group (8-<12 kg) had lower 3TC exposures than with the GL or TL (3TC AUC(0-6 h) 1,102, 1,720 and 2,060 h*ng/ml, respectively; P<0.005) and had more subtherapeutic NVP C(0 h) (10 of 13 occasions versus the one-half and three-quarter tablet groups). Compared with Western paediatric cohorts, Malawians had concentrations 30-40% lower for 3TC and d4T and 50% higher for NVP. CONCLUSIONS: Quartered multiples of Triomune 40 are appropriate for children 18-<22 kg and 28-<32 kg in weight; however, alternative formulations are suggested in children weighing 8-<12 kg.

Combining fosamprenavir with lopinavir/ritonavir substantially reduces amprenavir and lopinavir exposure: ACTG protocol A5143 results.

OBJECTIVE: To evaluate fosamprenavir/lopinavir (LPV)/ritonavir (RTV), fosamprenavir/RTV, or LPV/RTV in antiretroviral treatment-experienced patients. Lack of drug interaction data prompted a pharmacokinetic substudy to minimize subject risk. DESIGN: Multi-center, open-label, selectively randomized, steady-state pharmacokinetic study in HIV-infected subjects. METHODS: A planned independent interim review occurred after at least eight subjects were randomized to each arm. Subjects received twice daily LPV/RTV 400/100 mg (arm A; n = 8); fosamprenavir/RTV 700/100 mg (arm B; n = 8) or LPV/RTV/fosamprenavir 400/100/700 mg (arm C; n = 17). Plasma samples were collected over 12 h between study weeks 2 and 4. Pharmacokinetic parameters were compared based on a one-sided t-test on log-transformed data with a Peto stopping boundary (P < 0.001). RESULTS: Amprenavir mean area under the curve over 12 h (AUC0-12 h) and concentration at 12 h (C12 h) (microg/ml) were, respectively, 42.7 microg x h/ml (range, 33.1-55.1) and 2.4 microg/ml (range, 1.4-3.2) in arm B and 17.4 microg x h/ml (range, 4.6-41.3) and 0.9 microg/ml (range, 0.2-2.7) in arm C: geometric mean ratio (GMR) arm C:B was 0.36 [99.9% upper confidence boundary (UCB), 0.64] and 0.31 (99.9% h UCB, 0.61), respectively (P < or = 0.0001). Lopinavir AUC0-12 h and C12 h were, respectively, 95.3 microg x h/ml (range, 60.3-119.3) and 6.3 microg/ml (range, 2.2-9.2) in arm A and 54.4 microg x h/ml (range, 23.5-112.2) and 3.0 microg/ml (range, 0.4-7.9) in arm C: GMR arm C:A of 0.52 (99.9% UCB, 0.89) and 0.39 (99.9% UCB, 0.98), respectively (P < or = 0.0008). Ritonavir exposure was not significantly different between arms. CONCLUSION: APV and LPV exposures are significantly reduced using LPV/RTV/fosamprenavir, possibly increasing the risk of virologic failure. Consequently, A5143 was closed to enrollment.