In vitro investigations into the roles of drug transporters and metabolizing enzymes in the disposition and drug interactions of dolutegravir, a HIV integrase inhibitor

Pharmacokinetic drug interactions of integrase strand transfer inhibitors

The integrase strand transfer inhibitor (INSTI)-containing regimens are currently considered as the first-line treatment of human immunodeficiency virus (HIV) infection. Although possessing a common mechanism of action to inhibit HIV integrase irreversibly to stop HIV replication cycle, the INSTIs, including raltegravir, elvitegravir, dolutegravir, and bictegravir, differ in pharmacokinetic characteristics. While raltegravir undergoes biotransformation by the UDP-glucuronosyltransferases (UGTs), elvitegravir is primarily metabolized by cytochrome P450 (CYP) 3A4 and co-formulated with cobicistat to increase its plasma exposure. The metabolism pathways of dolutegravir and bictegravir are similar, both including CYP3A and UGT1A1, and both agents are substrates to different drug transporters. Because of their differences in metabolism, INSTIs interact with other medications differently through CYP enzymes and transporters as inducers or inhibitors. These drug interactions may become an important consideration in the long-term clinical use because the life expectancy of people with HIV (PWH) approaches to that of the general population. Also, common geriatric challenges such as multimorbidity and polypharmacy have been increasingly recognized in PWH. This review provides a summary of pharmacokinetic interactions with INSTIs and future perspectives in implications of INSTI drug interactions.

In vitro investigations into the roles of CYP450 enzymes and drug transporters in the drug interactions of zanubrutinib, a covalent Bruton's tyrosine kinase inhibitor

Zanubrutinib is a highly selective, potent, orally available, targeted covalent inhibitor (TCI) of Bruton's tyrosine kinase (BTK). This work investigated the in vitro drug metabolism and transport of zanubrutinib, and its potential for clinical drug-drug interactions (DDIs). Phenotyping studies indicated cytochrome P450 (CYP) 3A are the major CYP isoform responsible for zanubrutinib metabolism, which was confirmed by a clinical DDI study with itraconazole and rifampin. Zanubrutinib showed mild reversible inhibition with half maximal inhibitory concentration (IC50 ) of 4.03, 5.69, and 7.80 μM for CYP2C8, CYP2C9, and CYP2C19, respectively. Data in human hepatocytes disclosed induction potential for CYP3A4, CYP2B6, and CYP2C enzymes. Transport assays demonstrated that zanubrutinib is not a substrate of human breast cancer resistance protein (BCRP), organic anion transporting polypeptide (OATP)1B1/1B3, organic cation transporter (OCT)2, or organic anion transporter (OAT)1/3 but is a potential substrate of the efflux transporter P-glycoprotein (P-gp). Additionally, zanubrutinib is neither an inhibitor of P-gp at concentrations up to 10.0 μM nor an inhibitor of BCRP, OATP1B1, OATP1B3, OAT1, and OAT3 at concentrations up to 5.0 μM. The in vitro results with CYPs and transporters were correlated with the available clinical DDIs using basic models and mechanistic static models. Zanubrutinib is not likely to be involved in transporter-mediated DDIs. CYP3A inhibitors and inducers may impact systemic exposure of zanubrutinib. Dose adjustments may be warranted depending on the potency of CYP3A modulators.

Lack of a Clinically Meaningful Drug Interaction Between the HIV-1 Antiretroviral Agents Islatravir, Dolutegravir, and Tenofovir Disoproxil Fumarate

Islatravir, an investigational nucleoside reverse transcriptase translocation inhibitor, is in clinical development for the treatment and prevention of HIV‐1 infection. Because islatravir may be coadministered with other antiretroviral agents, assessment of potential drug‐drug interactions are warranted. This phase 1, open‐label, fixed‐sequence, 2‐period trial in adults without HIV (N = 12) assessed the safety and pharmacokinetic interactions of islatravir administered with dolutegravir and tenofovir disoproxil fumarate (TDF). In period 1, participants received a single oral dose of islatravir (20 mg). In period 2, participants received oral doses of dolutegravir (50 mg) and TDF (300 mg) once daily on days 1 through 11, with a single oral dose of islatravir (20 mg) coadministered on day 8. There were no clinically significant changes in islatravir, dolutegravir, or TDF pharmacokinetics following coadministration. Islatravir was generally well tolerated when administered alone or in combination with dolutegravir and TDF. Coadministration of islatravir, dolutegravir, and TDF is supported, with no clinically meaningful effect on pharmacokinetics, safety, or tolerability in participants without HIV.

Mechanistic Modeling of Placental Drug Transfer in Humans: How Do Differences in Maternal/Fetal Fraction of Unbound Drug and Placental Influx/Efflux Transfer Rates Affect Fetal Pharmacokinetics?

Background: While physiologically based pharmacokinetic (PBPK) models generally predict pharmacokinetics in pregnant women successfully, the confidence in predicting fetal pharmacokinetics is limited because many parameters affecting placental drug transfer have not been mechanistically accounted for. Objectives: The objectives of this study were to implement different maternal and fetal unbound drug fractions in a PBPK framework; to predict fetal pharmacokinetics of eight drugs in the third trimester; and to quantitatively investigate how alterations in various model parameters affect predicted fetal pharmacokinetics. Methods: The ordinary differential equations of previously developed pregnancy PBPK models for eight drugs (acyclovir, cefuroxime, diazepam, dolutegravir, emtricitabine, metronidazole, ondansetron, and raltegravir) were amended to account for different unbound drug fractions in mother and fetus. Local sensitivity analyses were conducted for various parameters relevant to placental drug transfer, including influx/efflux transfer clearances across the apical and basolateral membrane of the trophoblasts. Results: For the highly-protein bound drugs diazepam, dolutegravir and ondansetron, the lower fraction unbound in the fetus vs. mother affected predicted pharmacokinetics in the umbilical vein by ≥10%. Metronidazole displayed blood flow-limited distribution across the placenta. For all drugs, umbilical vein concentrations were highly sensitive to changes in the apical influx/efflux transfer clearance ratio. Additionally, transfer clearance across the basolateral membrane was a critical parameter for cefuroxime and ondansetron. Conclusion: In healthy pregnancies, differential protein binding characteristics in mother and fetus give rise to minor differences in maternal-fetal drug exposure. Further studies are needed to differentiate passive and active transfer processes across the apical and basolateral trophoblast membrane.

Pharmacokinetics and placental transfer of dolutegravir in pregnancy

Dolutegravir is currently recommended by the WHO as the preferred first-line treatment for all people with HIV, including pregnant women. Estimates indicate that, by 2024, nearly 22 million adults in low- and middle-income countries will have transitioned to dolutegravir-based ART. It is therefore critical that there is a clear appreciation and understanding of the risks that may be associated with in utero exposure to dolutegravir. In this review we consolidate data from studies on dolutegravir and the placenta. The studies have largely focused on the pharmacokinetics and placental transfer of dolutegravir in pregnancy. These include studies on transplacental transfer of dolutegravir, ex vivo placenta perfusion models, physiologically based pharmacokinetic (PBPK) models and animal studies. The data available clearly demonstrate that placental transfer of dolutegravir occurs in moderate to high concentrations. Intracellular placental dolutegravir has been demonstrated in the placental villous tissue. There are limited data suggesting that pregnancy is associated with decreased maternal dolutegravir levels. In addition, PBPK models have great potential in predicting the passage of drugs through the placenta and further contributing towards the elucidation of fetal exposure. The animal studies available demonstrate that in utero dolutegravir exposure can be associated with neural tube defects. Taking into consideration that antiretroviral exposure may be associated with poor placental development or function and increased risk of adverse effects to the fetus, it is crucially important that these risks are evaluated, especially with the rapid scale up of dolutegravir-based ART into national treatment programmes.

Comparative Clinical Pharmacokinetics and Pharmacodynamics of HIV-1 Integrase Strand Transfer Inhibitors: An Updated Review

Bictegravir, cabotegravir, dolutegravir, elvitegravir, and raltegravir are members of the latest class of antiretrovirals available to treat human immunodeficiency virus (HIV) infection, the integrase strand transfer inhibitors. Integrase strand transfer inhibitors are potent inhibitors of the HIV integrase enzyme with IC_90/95 values in the low nanogram per milliliter range and they retain antiviral activity against strains of HIV with acquired resistance to other classes of antiretrovirals. Each of the integrase strand transfer inhibitors have unique pharmacokinetic/pharmacodynamic properties, influencing their role in clinical use in specific subsets of patients. Cabotegravir, approved for use in Canada but not yet by the US Food and Drug Administration, is formulated in both oral and intramuscular formulations; the latter of which has shown efficacy as a long-acting extended-release formulation. Cabotegravir, raltegravir, and dolutegravir have minimal drug-drug interaction profiles, as their metabolism has minimal cytochrome P450 involvement. Conversely, elvitegravir metabolism occurs primarily via cytochrome P450 3A4 and requires pharmacokinetic boosting to achieve systemic exposures amenable to once-daily dosing. Bictegravir metabolism has similar contributions from both cytochrome P450 3A4 and uridine 5'-diphospho-glucuronosyltransferase 1A1. Bictegravir, dolutegravir, and raltegravir are recommended components of initial regimens for most people with HIV in the US adult and adolescent HIV treatment guidelines. This review summarizes and compares the pharmacokinetics and pharmacodynamics of the integrase strand transfer inhibitor agents, and describes specific pharmacokinetic considerations for persons with hepatic impairment, renal dysfunction, pregnancy, and co-infections.

PBPK Modeling as a Tool for Predicting and Understanding Intestinal Metabolism of Uridine 5'-Diphospho-glucuronosyltransferase Substrates

Uridine 5′-diphospho-glucuronosyltransferases (UGTs) are expressed in the small intestines, but prediction of first-pass extraction from the related metabolism is not well studied. This work assesses physiologically based pharmacokinetic (PBPK) modeling as a tool for predicting intestinal metabolism due to UGTs in the human gastrointestinal tract. Available data for intestinal UGT expression levels and in vitro approaches that can be used to predict intestinal metabolism of UGT substrates are reviewed. Human PBPK models for UGT substrates with varying extents of UGT-mediated intestinal metabolism (lorazepam, oxazepam, naloxone, zidovudine, cabotegravir, raltegravir, and dolutegravir) have demonstrated utility for predicting the extent of intestinal metabolism. Drug–drug interactions (DDIs) of UGT1A1 substrates dolutegravir and raltegravir with UGT1A1 inhibitor atazanavir have been simulated, and the role of intestinal metabolism in these clinical DDIs examined. Utility of an in silico tool for predicting substrate specificity for UGTs is discussed. Improved in vitro tools to study metabolism for UGT compounds, such as coculture models for low clearance compounds and better understanding of optimal conditions for in vitro studies, may provide an opportunity for improved in vitro–in vivo extrapolation (IVIVE) and prospective predictions. PBPK modeling shows promise as a useful tool for predicting intestinal metabolism for UGT substrates.

Islatravir Is Not Expected to Be a Victim or Perpetrator of Drug-Drug Interactions via Major Drug-Metabolizing Enzymes or Transporters

Islatravir (MK-8591) is a nucleoside reverse transcriptase translocation inhibitor in development for the treatment and prevention of HIV-1. The potential for islatravir to interact with commonly co-prescribed medications was studied in vitro. Elimination of islatravir is expected to be balanced between adenosine deaminase-mediated metabolism and renal excretion. Islatravir did not inhibit uridine diphosphate glucuronosyltransferase 1A1 or cytochrome p450 (CYP) enzymes CYP1A2, 2B6, 2C8, 2C9, 2C19, 2D6, or 3A4, nor did it induce CYP1A2, 2B6, or 3A4. Islatravir did not inhibit hepatic transporters organic anion transporting polypeptide (OATP) 1B1, OATP1B3, organic cation transporter (OCT) 1, bile salt export pump (BSEP), multidrug resistance-associated protein (MRP) 2, MRP3, or MRP4. Islatravir was neither a substrate nor a significant inhibitor of renal transporters organic anion transporter (OAT) 1, OAT3, OCT2, multidrug and toxin extrusion protein (MATE) 1, or MATE2K. Islatravir did not significantly inhibit P-glycoprotein and breast cancer resistance protein (BCRP); however, it was a substrate of BCRP, which is not expected to be of clinical significance. These findings suggest islatravir is unlikely to be the victim or perpetrator of drug-drug interactions with commonly co-prescribed medications, including statins, diuretics, anti-diabetic drugs, proton pump inhibitors, anticoagulants, benzodiazepines, and selective serotonin reuptake inhibitors.

Transporter-mediated drug-drug interactions: advancement in models, analytical tools, and regulatory perspective

Drug-drug interactions mediated by transporters are a serious clinical concern hence a tremendous amount of work has been done on the characterization of the transporter-mediated proteins in humans and animals. The underlying mechanism for the transporter-mediated drug-drug interaction is the induction or inhibition of the transporter which is involved in the cellular uptake and efflux of drugs. Transporter of the brain, liver, kidney, and intestine are major determinants that alter the absorption, distribution, metabolism, excretion profile of drugs, and considerably influence the pharmacokinetic profile of drugs. As a consequence, transporter proteins may affect the therapeutic activity and safety of drugs. However, mounting evidence suggests that many drugs change the activity and/or expression of the transporter protein. Accordingly, evaluation of drug interaction during the drug development process is an integral part of risk assessment and regulatory requirements. Therefore, this review will highlight the clinical significance of the transporter, their role in disease, possible cause underlying the drug-drug interactions using analytical tools, and update on the regulatory requirement. The recent in-silico approaches which emphasize the advancement in the discovery of drug-drug interactions are also highlighted in this review. Besides, we discuss several endogenous biomarkers that have shown to act as substrates for many transporters, which could be potent determinants to find the drug-drug interactions mediated by transporters. Transporter-mediated drug-drug interactions are taken into consideration in the drug approval process therefore we also provided the extrapolated decision trees from in-vitro to in-vivo, which may trigger the follow-up to clinical studies.

In vitro assessment of the potential for dolutegravir to affect hepatic clearance of levonorgestrel

Objectives:

The World Health Organization recommends that all countries adopt dolutegravir-based antiretroviral therapy as the preferred regimen for all individuals living with HIV. Levonorgestrel is a commonly used hormonal contraceptive, which undergoes drug–drug interactions with some antiretrovirals, but the potential interaction between dolutegravir and levonorgestrel has not been examined. We aimed to evaluate cytochrome P450 (CYP)-mediated levonorgestrel metabolism and quantify the effects of dolutegravir on levonorgestrel apparent intrinsic clearance (CL_int.app.) and CYP gene expression.

Methods:

In vitro CYP-mediated CL_int.app. of levonorgestrel was quantified using a recombinant human CYP (rhCYP) enzyme system. A primary human hepatocyte model of drug metabolism was used to assess the effects of dolutegravir on (1) levonorgestrel CL_int.app., using liquid chromatography-tandem mass spectrometry, and (2) the expression of specific CYP enzymes, using quantitative real-time polymerase chain reaction.

Results:

Levonorgestrel clearance was mediated by multiple rhCYPs, including rhCYP3A4. Under control conditions, levonorgestrel CL_int.app. was 22.4 ± 5.0 μL/min/10⁶ hepatocytes. Incubation with 43.1 nM of unbound dolutegravir elevated levonorgestrel CL_int.app. to 31.4 ± 7.8 μL/min/10⁶ hepatocytes (P = 0.168), while 142.23 nM increased levonorgestrel CL_int.app. to 37.0 ± 2.9 μL/min/10⁶ hepatocytes (P = 0.012). Unbound dolutegravir ≥ 431 nM induced expression of CYP3A4 (≥ two-fold) in a dose-dependent manner, while 1.44 μM of unbound dolutegravir induced CYP2B6 expression 2.2 ± 0.3-fold (P = 0.0004).

Conclusions:

In summary, this in vitro study suggests that dolutegravir has the potential to increase hepatic clearance of levonorgestrel by inducing both CYP3A and non-CYP3A enzymes. The observed in vitro dolutegravir–levonorgestrel drug–drug interaction should be further examined in clinical studies.

Dolutegravir pharmacokinetics during co-administration with either artemether/lumefantrine or artesunate/amodiaquine

BACKGROUND

In sub-Saharan Africa, artemisinin-containing therapies for malaria treatment are regularly co-administered with ART. Currently, dolutegravir-based regimens are recommended as first-line therapy for HIV across most of Africa.

OBJECTIVES

To investigate the population pharmacokinetics of dolutegravir during co-administration with artemether/lumefantrine or artesunate/amodiaquine, two commonly used antimalarial therapies.

METHODS

We developed a population pharmacokinetic model of dolutegravir with data from 26 healthy volunteers in two Phase 2 studies with a total of 403 dolutegravir plasma concentrations at steady state. Volunteers received 50 mg of dolutegravir once daily alone or in combination with standard treatment doses of artemether/lumefantrine (80/480 mg) or artesunate/amodiaquine (200/540 mg).

RESULTS

A two-compartment model with first-order elimination and transit compartment absorption best described the concentration-time data of dolutegravir. Typical population estimates for clearance, absorption rate constant, central volume, peripheral volume and mean absorption transit time were 0.713 L/h, 1.68 h-1, 13.2 L, 5.73 L and 1.18 h, respectively. Co-administration of artemether/lumefantrine or artesunate/amodiaquine increased dolutegravir clearance by 10.6% (95% CI 4.09%-34.5%) and 26.4% (95% CI 14.3%-51.4%), respectively. Simulations showed that simulated trough concentrations of dolutegravir alone or in combination with artemether/lumefantrine or artesunate/amodiaquine are maintained above the dolutegravir protein-adjusted IC90 of 0.064 mg/L for more than 99% of the individuals.

CONCLUSIONS

Dolutegravir dose adjustments are not necessary for patients who are taking standard 3 day treatment doses of artemether/lumefantrine or artesunate/amodiaquine.

Characterization of Hepatic UDP-Glucuronosyltransferase Enzyme Abundance-Activity Correlations and Population Variability Using a Proteomics Approach and Comparison with Cytochrome P450 Enzymes

The expression of ten major drug-metabolizing UDP-glucuronosyltransferase (UGT) enzymes in a panel of 130 human hepatic microsomal samples was measured using a liquid chromatography-tandem mass spectrometry-based approach. Simultaneously, ten cytochromes P450 and P450 reductase were also measured, and activity-expression relationships were assessed for comparison. The resulting data sets demonstrated that, with the exception of UGT2B17, 10th to 90th percentiles of UGT expression spanned 3- to 8-fold ranges. These ranges were small relative to ranges of reported mean UGT enzyme expression across different laboratories. We tested correlation of UGT expression with enzymatic activities using selective probe substrates. A high degree of abundance-activity correlation (Spearman's rank correlation coefficient > 0.6) was observed for UGT1As (1A1, 3, 4, 6) and cytochromes P450. In contrast, protein abundance and activity did not correlate strongly for UGT1A9 and UGT2B enzymes (2B4, 7, 10, 15, and 17). Protein abundance was strongly correlated for UGTs 2B7, 2B10, and 2B15. We suggest a number of factors may contribute to these differences including incomplete selectivity of probe substrates, correlated expression of these UGT2B isoforms, and the impact of splice and polymorphic variants on the peptides used in proteomics analysis, and exemplify this in the case of UGT2B10. Extensive correlation analyses identified important criteria for validating the fidelity of proteomics and enzymatic activity approaches for assessing UGT variability, population differences, and ontogenetic changes. SIGNIFICANCE STATEMENT: Protein expression data allow detailed assessment of interindividual variability and enzyme ontogeny. This study has observed that expression and enzyme activity are well correlated for hepatic UGT1A enzymes and cytochromes P450. However, for the UGT2B family, caution is advised when assuming correlation of expression and activity as is often done in physiologically based pharmacokinetic modeling. This can be due to incomplete probe substrate specificities, but may also be related to presence of inactive UGT protein materials and the effect of splicing variations.

HIV in pregnancy: Mother-to-child transmission, pharmacotherapy, and toxicity

An estimated 1.3 million pregnant women were living with HIV in 2018. HIV infection is associated with adverse pregnancy outcomes and all HIV-positive pregnant women, regardless of their clinical stage, should receive a combination of antiretroviral drugs to suppress maternal viral load and prevent vertical fetal infection. Although antiretroviral treatment in pregnant women has undoubtedly minimized mother-to-child transmission of HIV, several uncertainties remain. For example, while pregnancy is accompanied by changes in pharmacokinetic parameters, relevant data from clinical studies are lacking. Similarly, long-term adverse effects of exposure to antiretrovirals on fetuses have not been studied in detail. Here, we review current knowledge on HIV effects on the placenta and developing fetus, recommended antiretroviral regimens, and pharmacokinetic considerations with particular focus on placental transport. We also discuss recent advances in antiretroviral research and potential effects of antiretroviral treatment on placental/fetal development and programming.

Pharmacokinetics and antiviral activity of cabotegravir and rilpivirine in cerebrospinal fluid following long-acting injectable administration in HIV-infected adults

Background

Long-acting (LA) formulations of cabotegravir, an HIV integrase inhibitor, and rilpivirine, an NNRTI, are in development as monthly or 2 monthly intramuscular (IM) injections for maintenance of virological suppression.

Objectives

To evaluate cabotegravir and rilpivirine CSF distribution and HIV-1 RNA suppression in plasma and CSF in HIV-infected adults participating in a substudy of the Phase 2b LATTE-2 study (NCT02120352).

Methods

Eighteen participants receiving cabotegravir LA 400 mg + rilpivirine LA 600 mg IM [every 4 weeks (Q4W), n = 3] or cabotegravir LA 600 mg + rilpivirine LA 900 mg IM [every 8 weeks (Q8W), n = 15] with plasma HIV-1 RNA <50 copies/mL enrolled. Paired steady-state CSF and plasma concentrations were evaluable in 16 participants obtained 7 (±3) days after an injection visit. HIV-1 RNA in CSF and plasma were assessed contemporaneously using commercial assays.

Results

Median total CSF concentrations in Q4W and Q8W groups, respectively, were 0.011 μg/mL and 0.013 μg/mL for cabotegravir (0.30% and 0.34% of the paired plasma concentrations) and 1.84 ng/mL and 1.67 ng/mL for rilpivirine (1.07% and 1.32% of paired plasma concentrations). Cabotegravir and rilpivirine total CSF concentrations exceeded their respective in vitro EC₅₀ for WT HIV-1 (0.10 ng/mL and 0.27 ng/mL, respectively). All 16 participants had HIV-1 RNA <50 copies/mL in plasma and CSF, and 15 of 16 participants had HIV-1 RNA <2 copies/mL in CSF.

Conclusions

A dual regimen of cabotegravir LA and rilpivirine LA achieved therapeutic concentrations in the CSF resulting in effective virological control in CSF.

Evaluation of the effect of UGT1A1 polymorphisms on the pharmacokinetics of oral and long-acting injectable cabotegravir

Background

Cabotegravir is an HIV integrase inhibitor in clinical development with both oral and long-acting (LA) injectable formulations. Cabotegravir is primarily metabolized by uridine 5′-diphospho-glucuronosyltransferase (UGT) 1A1, a known polymorphic enzyme with functional variants that can affect drug metabolism and exposure.

Objectives

To investigate the pharmacogenetic effects of the reduced-function alleles UGT1A1*6, UGT1A1*28 and/or UGT1A1*37 on steady-state pharmacokinetics (PK) and safety of oral cabotegravir (30 mg/day) and intramuscular cabotegravir LA (400 mg every 4 weeks or 600 mg every 8 weeks).

Methods

Plasma cabotegravir PK was assessed in 346 UGT-genotyped participants with and without UGT1A1 functional variants across six studies (four Phase I and two Phase II) of oral cabotegravir, including 215 HIV-infected participants who received oral cabotegravir followed by cabotegravir LA. Changes from baseline in total bilirubin and ALT were assessed in one study (LATTE; NCT01641809).

Results

Statistically significant (P < 0.05) associations were observed between UGT1A1 genotype and plasma cabotegravir PK parameters, with 28%–50% increases following oral cabotegravir [plasma cabotegravir concentration at the end of the dosing interval (C_tau), 1.50-fold; AUC_tau, 1.41-fold; and C_max, 1.28-fold] and 16%–24% increases following cabotegravir LA administration (48 week C_tau, 1.24-fold; AUC_tau, 1.16-fold; and C_max, 1.18-fold) among those with low-versus-normal genetically predicted UGT1A1 activity. A statistically significant (P < 10⁻⁵) association between predicted UGT1A1 activity and maximum change in total bilirubin was also observed (2.45-fold asymptomatic increase for low versus normal) without a corresponding change in ALT.

Conclusions

This modest increase in oral and parenteral cabotegravir exposure associated with a reduced function of UGT1A1 is not considered clinically relevant based on accumulated safety data; no dose adjustment is required.

Prediction of dolutegravir pharmacokinetics and dose optimization in neonates via physiologically based pharmacokinetic (PBPK) modelling

BACKGROUND

Only a few antiretroviral drugs (ARVs) are recommended for use during the neonatal period and there is a need for more to be approved to increase treatment and prophylaxis strategies. Dolutegravir, a selective integrase inhibitor, has potential for treatment of HIV infection and prophylaxis of transmission in neonates.

OBJECTIVES

To model the pharmacokinetics of dolutegravir in neonates and to simulate a theoretical optimal dosing regimen.

METHODS

The physiologically based pharmacokinetic (PBPK) model was built incorporating the age-related changes observed in neonates. Virtual neonates between 0 and 28 days were simulated. The model was validated against observed clinical data for raltegravir and midazolam in neonates, prior to the prediction of dolutegravir pharmacokinetics.

RESULTS

Both raltegravir and midazolam passed the criteria for model qualification, with simulated data within 1.8-fold of clinical data. The qualified model predicted the pharmacokinetics for several multidose regimens of dolutegravir. Regimen 6 involved 5 mg doses with a 48 h interval from Day 1-20, increasing to 5 mg once daily on Week 3, yielding AUC and Ctrough values of 37.2 mg·h/L and 1.3 mg/L, respectively. These exposures are consistent with those observed in paediatric patients receiving dolutegravir.

CONCLUSIONS

Dolutegravir pharmacokinetics were successfully simulated in the neonatal PBPK model. The predictions suggest that during the first 3 weeks of life a 5 mg dose administered every 48 h may achieve plasma exposures needed for therapy and prophylaxis.

Short Communication: Comparing Lamivudine+Dolutegravir and Bictegravir/Emtricitabine/Tenofovir Alafenamide as Switch Strategies: Preliminary Results from Clinical Practice

We tried to investigate and compare the safety of a dual therapy (DT) with dolutegravir+lamivudine (DTG +3TC) versus bictegravir/emtricitabine/tenofovir alafenamide (BIC/FTC/TAF). We performed a retrospective analysis in a cohort of virologically suppressed HIV+ pts switching to DT or BIC in our center. Primary endpoint was to evaluate time to treatment discontinuation (TD) for any cause. Survival analysis was employed to determine time to TD and its predictors were analyzed by Cox regression. Moreover, we collected viro-immunological parameters as well as markers of renal function and lipid profile at baseline and after 24 weeks and assessed changes through nonparametric tests. We analyzed 476 patients: 350 starting a DT and 126 starting BIC. Overall, we registered 21 TD: 15 in the DT group during 170 patient-years of follow-up (PYFU) (a rate of 8.8 per 100 PYFU) and 6 in the BIC one during 48 PYFU (12.5 per 100 PYFU). Estimated probabilities of maintaining study regimen after 24 weeks were 95.5% [standard deviation (SD) ±1.1] in the DT group and 94.9% (SD ±2.0) in the BIC group, with no significant differences between them (log-rank p = .639). Concerning metabolic profile, in the DT group, after 24 weeks, triglycerides decreased significantly (median change -14 mg/dL, p < .001), whereas high-density lipoprotein cholesterol increased (+3 mg/dL, p = .031). In the BIC group, meanwhile, we observed a significant decrease in low-density lipoprotein cholesterol after 24 weeks (-13 mg/dL, p = .026). Both optimization strategies showed high tolerability in the short term in experienced pts, with few differences between them. Further studies are needed to properly assess the matter.

Comparative safety review of recommended, first-line single-tablet regimens in patients with HIV

Introduction Different single-tablet regimens (STRs), containing one or two nucleoside reverse transcriptase inhibitors (NRTIs) plus an anchor drug, are available for the use in naïve, HIV-infected patients. Despite some restrictions in the use of particular regimens in certain situations (e.g., HBV coinfection), International guidelines do not provide indications to prefer any regimen over others concerning the tolerability profile. We aimed to assess advantages and disadvantages of the most prescribed STRs.Areas covered An extensive review of articles published in English language was conducted on PubMed, looking for evidence about STRs in naïve, HIV-infected population. Safety outcomes of registrational trials were assessed, giving priority to studies directly comparing STRs included in our research (abacavir/lamivudine/dolutegravir, tenofovir alafenamide/emtricitabine/bictegravir, lamivudine/dolutegravir, tenofovir alafenamide/emtricitabine/darunavir/cobicistat, tenovofir disoproxil fumarate/lamivudine/doravirine). Data from cohort studies and meta-analyses were also assessed, extrapolating the main evidence about the combinations of interest.Expert opinion Integrase inhibitors (InsTIs)-based regimens have few interruptions for adverse events and few drug-related adverse events, with tenofovir alafenamide/emtricitabine/dolutegravir and lamivudine/dolutegravir being the most tolerable ones. However, neuropsychiatric adverse events and metabolic issues could prompt the alternative use of darunavir or doravirine-based combinations, even if a superior safety profile of these combinations over InSTIs has yet to be demonstrated.

Neurotoxicities in the treatment of HIV between dolutegravir, rilpivirine and dolutegravir/rilpivirine: a meta-analysis

OBJECTIVE

To assess the risk of neuropsychiatric adverse effects (ie, depression, anxiety, insomnia, dizziness, suicidal behaviour) among patients treated with rilpivirine, dolutegravir and dolutegravir/rilpivirine.

DESIGN

This is a systematic review and meta-analysis of randomised controlled trials. Quality of evidence was assessed using Jadad scoring system.

DATA SOURCES

Three electronic databases were searched for available publications up to 1 May 2020. Searches included relevant studies, trial registers, conference proceeding abstracts and grey literature.

INCLUSION CRITERIA

Randomised controlled trials with data focused on adult participants (ie, 18 years of age or older) receiving dolutegravir 50 mg, rilpivirine 25 mg or combination of dolutegravir 50 mg/rilpivirine 25 mg once daily.

RESULTS

Twenty studies with a minimum duration of 48 weeks and average Jadad score of 4 were included (n=10 998). Primary objective demonstrated a relative risk (RR) synergistic effect on depressive symptoms for dolutegravir/rilpivirine (RR=2.82; 95% CI (1.12 to 7.10)) when compared with dolutegravir (RR=1.10; 95% CI (0.88 to 1.38)) and rilpivirine (RR=1.08; 95% CI (0.80 to 1.48)). Secondary objectives showed no difference between dolutegravir, rilpivirine and dolutegravir/rilpivirine to efavirenz. Additionally, excluding efavirenz studies, dolutegravir and dolutegravir/rilpivirine yielded increased depression (RR=1.34; 95% CI (1.04 to 1.74)).

CONCLUSION

The combination of dolutegravir/rilpivirine appears to increase the risk of depressive symptoms. Despite the increase, the clinical significance is unknown and needs further study. Additionally, neurotoxicity risk appears similar between dolutegravir, rilpivirine and dolutegravir/rilpivirine antiretroviral therapy when compared with efavirenz-based antiretroviral therapy.

Renal function impairment in cervical cancer patients treated with cisplatin-based chemoradiation: A review of medical records in a Zimbabwean outpatient department

Background

There is a potential increase in risk of renal function impairment among patients with invasive cervical cancer (ICC) who are HIV-positive and treated with cisplatin-based concurrent chemoradiation (CCRT). This concern is due to overlapping nephrotoxicity of the drugs, and nephropathy from the diseases themselves. There is limited literature available for the short-term renal outcomes for HIV-positive patients with ICC during routine clinical management. This study aimed to assess if HIV-infection increased the risk of renal impairment in ICC patients treated with CCRT, and explore the respective risk factors.

Materials and methods

This was a retrospective review of records of ICC patients treated with at least one cycle of weekly cisplatin during CCRT at the Parirenyatwa Radiotherapy Center from January 2017-December 2018. The RIFLE criteria were used to classify renal impairment. Analyses were performed with Fisher’s Exact tests, Wilcoxon rank sum tests. Odds ratios (OR) were generated using logistic regression. All statistical tests were 2-sided at a 5% level of significance.

Results

Seventy-two eligible patients were identified, 32 (44.44%) were HIV-positive. HIV-positive patients were younger (p = 0.002), had lower albumin levels (p = 0.014) and received lower cisplatin doses (p = 0.044). The mean percent reduction in estimated glomerular filtration rate (eGFR) from baseline was -19% (95% CI: -25.9% to -13.2%) for all patients. Thirty-one (43.1%) patients experienced renal impairment, 50% and 37.5% of HIV-positive and -negative patients respectively (p = 0.287). HIV-infection was associated with an adjusted OR of 1.16 (95% CI 0.35–3.43, p = 0.769). Baseline eGFR< 60ml/min was the only independent predictor of renal impairment, OR 0.25 (95% CI: 0.07–0.85). Baseline eGFR<60ml/min was also associated with receipt of lower cisplatin doses (p = 0.044).

Conclusion

HIV-infection was not associated with elevated risk of renal impairment. Patients with an eGFR<60ml/min appear to be managed more cautiously reducing their risk for renal impairment during cisplatin therapy. The high prevalence of renal impairment in this population suggests the need for optimization of pre-treatment protocols.

Physiologically Based Pharmacokinetic Modeling Framework to Predict Neonatal Pharmacokinetics of Transplacentally Acquired Emtricitabine, Dolutegravir, and Raltegravir

BACKGROUND AND OBJECTIVE

Little is understood about neonatal pharmacokinetics immediately after delivery and during the first days of life following intrauterine exposure to maternal medications. Our objective was to develop and evaluate a novel, physiologically based pharmacokinetic modeling workflow for predicting perinatal and postnatal disposition of commonly used antiretroviral drugs administered prenatally to pregnant women living with human immunodeficiency virus.

METHODS

Using previously published, maternal-fetal, physiologically based pharmacokinetic models for emtricitabine, dolutegravir, and raltegravir built with PK-Sim/MoBi^®, placental drug transfer was predicted in late pregnancy. The total drug amount in fetal compartments at term delivery was estimated and subsequently integrated as initial conditions in different tissues of a whole-body, neonatal, physiologically based pharmacokinetic model to predict drug concentrations in the neonatal elimination phase after birth. Neonatal elimination processes were parameterized according to published data. Model performance was assessed by clinical data.

RESULTS

Neonatal physiologically based pharmacokinetic models generally captured the initial plasma concentrations after delivery but underestimated concentrations in the terminal phase. The mean percentage error for predicted plasma concentrations was - 71.5%, - 33.8%, and 76.7% for emtricitabine, dolutegravir, and raltegravir, respectively. A sensitivity analysis suggested that the activity of organic cation transporter 2 and uridine diphosphate glucuronosyltransferase 1A1 during the first postnatal days in term newborns is ~11% and ~30% of that in adults, respectively.

CONCLUSIONS

These findings demonstrate the general feasibility of applying physiologically based pharmacokinetic models to predict washout concentrations of transplacentally acquired drugs in newborns. These models can increase the understanding of pharmacokinetics during the first postnatal days and allow the prediction of drug exposure in this vulnerable population.

Tetrahydrofurofuranoid Lignans, Eudesmin, Fargesin, Epimagnolin A, Magnolin, and Yangambin Inhibit UDP-Glucuronosyltransferase 1A1 and 1A3 Activities in Human Liver Microsomes

Eudesmin, fargesin, epimagnolin A, magnolin, and yangambin are tetrahydrofurofuranoid lignans with various pharmacological activities found in Magnoliae Flos. The inhibition potencies of eudesmin, fargesin, epimagnolin A, magnolin, and yangambin on six major human uridine 5'-diphospho-glucuronosyltransferase (UGT) activities in human liver microsomes were evaluated using liquid chromatography-tandem mass spectrometry and cocktail substrates. Eudesmin, fargesin, epimagnolin A, magnolin, and yangambin inhibited UGT1A1 and UGT1A3 activities, but showed negligible inhibition of UGT1A4, UGT16, UGT1A9, and UGT2B7 activities at 200 μM in pooled human liver microsomes. Moreover, eudesmin, fargesin, epimagnolin A, magnolin, and yangambin noncompetitively inhibited UGT1A1-catalyzed SN38 glucuronidation with K_i values of 25.7, 25.3, 3.6, 26.0, and 17.1 μM, respectively, based on kinetic analysis of UGT1A1 inhibition in pooled human liver microsomes. Conversely, the aforementioned tetrahydrofurofuranoid lignans competitively inhibited UGT1A3-catalyzed chenodeoxycholic acid 24-acyl-glucuronidation with 39.8, 24.3, 15.1, 37.6, and 66.8 μM, respectively in pooled human liver microsomes. These in vitro results suggest the necessity of evaluating whether the five tetrahydrofurofuranoid lignans can cause drug-drug interactions with UGT1A1 and UGT1A3 substrates in vivo.

Possible Herb-Drug Interaction Risk of Some Nutritional and Beauty Supplements on Antiretroviral Therapy in HIV Patients

This study was carried out to assess the drug interaction potential of a variety of beauty and sports/nutritional supplements when co-administered with antiviral drug therapy, especially anti-HIV drugs. Ethanolic extracts of seven dietary supplements (two beauty products, three nutritional protein supplement products and two weight loss/body building products) were examined in human liver cells (HepG2 cells and primary hepatocytes) for their influence on the hepatic metabolism of five antiviral drugs (elvitegravir, rilpivirine, tenofovir, dolutegravir, and cobicistat), all of which are substrates for a key drug metabolizing enzyme CYP3A4. Our results showed that six of the seven supplements caused a 1.5 - 2 fold induction in PXR transcriptional activity in HepG2 cells. PXR regulates the expression of key drug metabolizing enzymes including CYP3A4. Follow up studies indicated a 1.5 - 3 fold induction in CYP3A4 enzyme activity in HepG2 cells treated with these supplements. We further investigated the effects of the supplement on the metabolism of above mentioned anti-viral drugs in HepG2 cells and primary hepatocytes. Of the five drugs, rilpivirine and dolutegravir metabolism was increased by up to 2-folds over the no supplement control by some of the supplements. Our findings indicate that concomitant consumption of these products with anti-HIV drugs may compromise the efficacy of antivirals therapy due to supplement-induced metabolism via induction of CYP3A4 activity.

HIV-1 Integrase Inhibitors: A Comparative Review of Efficacy and Safety

The newest class of antiretrovirals for all persons living with HIV are the integrase strand transfer inhibitors (INSTIs). Since 2007, five INSTIs have been introduced: raltegravir, elvitegravir, dolutegravir, bictegravir, and cabotegravir. The INSTIs have favorable pharmacokinetic and pharmacodynamic properties, which contribute to both their effectiveness and their ease of use. With the exception of cabotegravir, each INSTI is US Food and Drug Administration approved for treatment-naïve individuals initiating antiretroviral therapy. All of the INSTIs, except raltegravir, are approved for antiretroviral treatment simplification for virologically suppressed patients without INSTI resistance. Data also support the use of dolutegravir and raltegravir in individuals with antiretroviral resistance as part of an optimized antiretroviral regimen. INSTIs are generally well tolerated by people living with HIV compared with older classes of antiretrovirals, but emerging data suggest that some INSTIs contribute to weight gain. Due to their efficacy, safety, and ease of use, HIV treatment guidelines recommend oral INSTIs as preferred components of antiretroviral therapy for individuals initiating therapy. The newest INSTI, cabotegravir, represents an alternative to oral administration of life-long antiretroviral therapy with the availability of a long-acting injectable formulation. This review summarizes the current use of INSTIs in adults living with HIV, highlighting the similarities and differences within the class related to pharmacodynamics, pharmacokinetics, safety, dosing, and administration that contribute to their role in modern antiretroviral therapy.

Clinical Pharmacokinetics of the Novel HIV-1 Non-Nucleoside Reverse Transcriptase Inhibitor Doravirine: An Assessment of the Effect of Patient Characteristics and Drug-Drug Interactions

Doravirine (MK-1439) is a novel non-nucleoside reverse transcriptase inhibitor indicated for the combination treatment of human immunodeficiency virus type-1 (HIV-1) infection. The recommended dose is 100 mg once daily. This review summarizes the pharmacokinetics of doravirine, the influence of intrinsic factors, and its drug-drug interaction (DDI) profile. Following oral administration, doravirine is rapidly absorbed (median time to maximum plasma concentration, 1-4 h) and undergoes cytochrome P450 (CYP)3A-mediated oxidative metabolism. Steady-state geometric means for AUC0-24, C24, and Cmax in individuals with HIV-1 following administration of doravirine 100 mg once daily are 37.8 μM·h, 930 nM, and 2260 nM, respectively. Age, gender, severe renal impairment, and moderate hepatic impairment have no clinically meaningful effect on doravirine pharmacokinetics, and there is limited potential for DDIs. No dose adjustment is necessary when doravirine is co-administered with strong CYP3A inhibitors. However, doravirine is contraindicated with strong CYP3A inducers (e.g., rifampin), and dose adjustment of doravirine is recommended for co-administration with the moderate CYP3A inducer, rifabutin. Included in this review are clinical trial data from phase I pharmacokinetic trials, including DDI trials and trials in participants with renal and hepatic disease but without HIV-1 infection (N = 326), as well as phase I, II, and III safety and efficacy trials in participants living with HIV-1 (N = 991). Based on these data, the pharmacokinetic profile of doravirine supports its use in diverse populations living with HIV-1 and allows co-administration with various antiretroviral agents and treatments for commonly occurring co-morbidities.

Organic Cation Transporters in Health and Disease

The organic cation transporters (OCTs) OCT1, OCT2, OCT3, novel OCT (OCTN)1, OCTN2, multidrug and toxin exclusion (MATE)1, and MATE kidney-specific 2 are polyspecific transporters exhibiting broadly overlapping substrate selectivities. They transport organic cations, zwitterions, and some uncharged compounds and operate as facilitated diffusion systems and/or antiporters. OCTs are critically involved in intestinal absorption, hepatic uptake, and renal excretion of hydrophilic drugs. They modulate the distribution of endogenous compounds such as thiamine, L-carnitine, and neurotransmitters. Sites of expression and functions of OCTs have important impact on energy metabolism, pharmacokinetics, and toxicity of drugs, and on drug-drug interactions. In this work, an overview about the human OCTs is presented. Functional properties of human OCTs, including identified substrates and inhibitors of the individual transporters, are described. Sites of expression are compiled, and data on regulation of OCTs are presented. In addition, genetic variations of OCTs are listed, and data on their impact on transport, drug treatment, and diseases are reported. Moreover, recent data are summarized that indicate complex drug-drug interaction at OCTs, such as allosteric high-affinity inhibition of transport and substrate dependence of inhibitor efficacies. A hypothesis about the molecular mechanism of polyspecific substrate recognition by OCTs is presented that is based on functional studies and mutagenesis experiments in OCT1 and OCT2. This hypothesis provides a framework to imagine how observed complex drug-drug interactions at OCTs arise. Finally, preclinical in vitro tests that are performed by pharmaceutical companies to identify interaction of novel drugs with OCTs are discussed. Optimized experimental procedures are proposed that allow a gapless detection of inhibitory and transported drugs.

HIV-1 Sanctuary Sites-the Role of Membrane-Associated Drug Transporters and Drug Metabolic Enzymes

Despite significant advances in the treatment of human immunodeficiency virus-1 (HIV) infection with highly active antiretroviral drug therapy, the persistence of the virus in cellular and anatomic reservoirs is a major obstacle preventing total HIV eradication. Viral persistence could result from a variety of contributing factors including, but not limited to, non-adherence to treatment and adverse drug reactions, latently infected cells carrying replication-competent virus, drug-drug interactions, and inadequate antiretroviral drug (ARV) concentrations reached in several anatomic sites such as the brain, testis, and gut-associated lymphoid tissues. The distribution of ARVs at specific sites of infection is primarily dependent on drug physicochemical properties and drug plasma protein binding, as well as drug efflux, influx, and metabolic processes. A thorough understanding of the functional roles of drug transporters and metabolic enzymes in the disposition of ARVs in immune cell types and tissues that are characterized as HIV reservoirs and sanctuaries is critical to overcome the challenge of suboptimal drug distribution at sites of persistent HIV infection. This review summarizes the current knowledge related to the expression and function of drug transporters and metabolic enzymes in HIV cellular and anatomic reservoirs, and their potential contribution to drug-drug interactions and insufficient drug concentration at these sites.

Population pharmacokinetics of dolutegravir: influence of drug-drug interactions in a real-life setting

OBJECTIVES

Dolutegravir is widely prescribed owing to its potent antiviral activity, high genetic barrier and good tolerability. The aim of this study was to characterize dolutegravir's pharmacokinetic profile and variability in a real-life setting and to identify individual factors and co-medications affecting dolutegravir disposition.

METHODS

A population pharmacokinetic model was developed using NONMEM®. Relevant demographic factors, clinical factors and co-medications were tested as potential covariates. Simulations based on the final model served to compare expected dolutegravir concentrations under standard and alternative dosage regimens in the case of drug-drug interactions.

RESULTS

A total of 620 dolutegravir plasma concentrations were collected from 521 HIV-infected individuals under steady-state conditions. A one-compartment model with first-order absorption and elimination best characterized dolutegravir pharmacokinetics. Typical dolutegravir apparent clearance (CL/F) was 0.93 L/h with 32% between-subject variability, the apparent volume of distribution was 20.2 L and the absorption rate constant was fixed to 2.24 h-1. Older age, higher body weight and current smoking were associated with higher CL/F. Atazanavir co-administration decreased dolutegravir CL/F by 38%, while darunavir modestly increased CL/F by 14%. Rifampicin co-administration showed the largest impact on CL/F. Simulations suggest that average dolutegravir trough concentrations are 63% lower after 50 mg/12h with rifampicin compared with a standard dosage of 50 mg/24h without rifampicin. Average trough concentrations after 100 mg/24h and 100 mg/12h with rifampicin are 92% and 25% lower than the standard dosage without rifampicin, respectively.

CONCLUSIONS

Patients co-treated with dolutegravir and rifampicin might benefit from therapeutic drug monitoring and individualized dosage increase, up to 100 mg/12 h in some cases.

Doing More With Less: Review of Dolutegravir-Lamivudine, a Novel Single-Tablet Regimen for Antiretroviral-Naïve Adults With HIV-1 Infection

OBJECTIVE

To review data on efficacy and safety of dolutegravir (DTG) and lamivudine (3TC) in treatment-naïve adults with HIV-1 infection.

DATA SOURCES

Phase III clinical trials and review articles were identified through PubMed (1996 to March 2020) and ClinicalTrials.gov (2000 to May 2020) using the keywords dolutegravir, lamivudine, and HIV.

STUDY SELECTION AND DATA EXTRACTION

Relevant clinical trials and review articles available in English evaluating efficacy and safety of DTG and 3TC were included.

DATA SYNTHESIS

The once-daily, single-tablet regimen of DTG/3TC is the first dual antiretroviral therapy (ART) recommended for initial therapy in treatment-naïve adults with HIV-1 infection. DTG and 3TC were compared with a regimen of DTG and tenofovir disoproxil fumarate/emtricitabine in the GEMINI studies and demonstrated noninferiority for the primary end point of virological suppression at up to 96 weeks. No treatment-emergent resistance mutations were identified in a small group of participants who did not reach virological suppression. The regimen is well tolerated, and the most common adverse events reported in trials include headache, diarrhea, nausea, insomnia, and fatigue.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

This dual-ART regimen is a favorable treatment option for ART-naïve patients with HIV-1 RNA <500 000 copies/mL, absence of hepatitis B virus, and no resistance to DTG or 3TC. Benefits of dual ART include reduction in treatment-related adverse events and toxicities, drug interactions, and cost. In addition, the once-daily, single-tablet formulation promotes adherence.

CONCLUSIONS

DTG/3TC has demonstrated efficacy in maintaining virological suppression in ART-naïve patients at up to 96 weeks while minimizing treatment-related adverse events and toxicities.

Assessment of drug interaction potential between the HCV direct-acting antiviral agents elbasvir/grazoprevir and the HIV integrase inhibitors raltegravir and dolutegravir

BACKGROUND

Elbasvir/grazoprevir is a once-daily fixed-dose combination therapy for the treatment of chronic HCV infection, including HCV/HIV coinfection.

OBJECTIVES

To evaluate the pharmacokinetic interaction of elbasvir and grazoprevir with raltegravir or dolutegravir.

METHODS

Three open-label trials in healthy adult participants were conducted. In the raltegravir trials, participants received a single dose of raltegravir 400 mg, a single dose of elbasvir 50 mg or grazoprevir 200 mg, and raltegravir with either elbasvir or grazoprevir. In the dolutegravir trial, participants received a single dose of dolutegravir 50 mg alone or co-administered with once-daily elbasvir 50 mg and grazoprevir 200 mg.

RESULTS

The raltegravir AUC0-∞ geometric mean ratio (GMR) (90% CI) was 1.02 (0.81-1.27) with elbasvir and 1.43 (0.89-2.30) with grazoprevir. Dolutegravir AUC0-∞ GMR (90% CI) was 1.16 (1.00-1.34) with elbasvir and grazoprevir. The elbasvir AUC0-∞ GMR (90% CI) was 0.81 (0.57-1.17) with raltegravir and 0.98 (0.93-1.04) with dolutegravir. The grazoprevir AUC0-24 GMR (90% CI) was 0.89 (0.72-1.09) with raltegravir and 0.81 (0.67-0.97) with dolutegravir.

CONCLUSIONS

Elbasvir or grazoprevir co-administered with raltegravir or dolutegravir resulted in no clinically meaningful drug-drug interactions and was generally well tolerated. These results support the assertion that no dose adjustments for elbasvir, grazoprevir, raltegravir or dolutegravir are needed for co-administration in HCV/HIV-coinfected people.

Prediction of Maternal and Fetal Pharmacokinetics of Dolutegravir and Raltegravir Using Physiologically Based Pharmacokinetic Modeling

BACKGROUND

Predicting drug pharmacokinetics in pregnant women including placental drug transfer remains challenging. This study aimed to develop and evaluate maternal-fetal physiologically based pharmacokinetic models for two antiretroviral drugs, dolutegravir and raltegravir.

Pharmacokinetics of HIV-Integrase Inhibitors During Pregnancy: Mechanisms, Clinical Implications and Knowledge Gaps

Prevention of mother-to-child transmission of HIV and optimal maternal treatment are the most important goals of antiretroviral therapy in pregnant women with HIV. These goals may be at risk due to possible reduced exposure during pregnancy caused by physiological changes. Limited information is available on the impact of these physiological changes. This is especially true for HIV-integrase inhibitors, a relatively new class of drugs, recommended first-line agents and hence used by a large proportion of HIV-infected patients. Therefore, the objective of this review is to provide a detailed overview of the pharmacokinetics of HIV-integrase inhibitors in pregnancy. Second, this review defines potential causes for the change in pharmacokinetics of HIV-integrase inhibitors during pregnancy. Despite increased clearance, for raltegravir 400 mg twice daily and dolutegravir 50 mg once daily, exposure during pregnancy seems adequate; however, for elvitegravir, the proposed minimal effective concentration is not reached during pregnancy. Lower exposure to these drugs may be caused by increased hormone levels and, subsequently, enhanced drug metabolism during pregnancy. The pharmacokinetics of bictegravir and cabotegravir, which are under development, have not yet been evaluated in pregnant women. New studies need to prospectively assess whether adequate exposure is reached in pregnant women using these new HIV-integrase inhibitors. To further optimize antiretroviral treatment in pregnant women, studies need to unravel the underlying mechanisms behind the changes in the pharmacokinetics of HIV-integrase inhibitors during pregnancy. More knowledge on altered pharmacokinetics during pregnancy and the underlying mechanisms contribute to the development of effective and safe antiretroviral therapy for HIV-infected pregnant women.

Rociletinib (CO-1686) enhanced the efficacy of chemotherapeutic agents in ABCG2-overexpressing cancer cells in vitro and in vivo

Overexpression of adenosine triphosphate (ATP)-binding cassette subfamily G member 2 (ABCG2) in cancer cells is known to cause multidrug resistance (MDR), which severely limits the clinical efficacy of chemotherapy. Currently, there is no FDA-approved MDR modulator for clinical use. In this study, rociletinib (CO-1686), a mutant-selective epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI), was found to significantly improve the efficacy of ABCG2 substrate chemotherapeutic agents in the transporter-overexpressing cancer cells in vitro and in MDR tumor xenografts in nude mice, without incurring additional toxicity. Mechanistic studies revealed that in ABCG2-overexpressing cancer cells, rociletinib inhibited ABCG2-mediated drug efflux and increased intracellular accumulation of ABCG2 probe substrates. Moreover, rociletinib, inhibited the ATPase activity, and competed with [¹²⁵I] iodoarylazidoprazosin (IAAP) photolabeling of ABCG2. However, ABCG2 expression at mRNA and protein levels was not altered in the ABCG2-overexpressing cells after treatment with rociletinib. In addition, rociletinib did not inhibit EGFR downstream signaling and phosphorylation of protein kinase B (AKT) and extracellular signal-regulated kinase (ERK). Our results collectively showed that rociletinib reversed ABCG2-mediated MDR by inhibiting ABCG2 efflux function, thus increasing the cellular accumulation of the transporter substrate anticancer drugs. The findings advocated the combination use of rociletinib and other chemotherapeutic drugs in cancer patients with ABCG2-overexpressing MDR tumors.

An Individual Participant Data Population Pharmacokinetic Meta-analysis of Drug-Drug Interactions between Lumefantrine and Commonly Used Antiretroviral Treatment

Treating malaria in HIV-coinfected individuals should consider potential drug-drug interactions. Artemether-lumefantrine is the most widely recommended treatment for uncomplicated malaria globally. Lumefantrine is metabolized by CYP3A4, an enzyme that commonly used antiretrovirals often induce or inhibit. A population pharmacokinetic meta-analysis was conducted using individual participant data from 10 studies with 6,100 lumefantrine concentrations from 793 nonpregnant adult participants (41% HIV-malaria-coinfected, 36% malaria-infected, 20% HIV-infected, and 3% healthy volunteers).

Treating malaria in HIV-coinfected individuals should consider potential drug-drug interactions. Artemether-lumefantrine is the most widely recommended treatment for uncomplicated malaria globally. Lumefantrine is metabolized by CYP3A4, an enzyme that commonly used antiretrovirals often induce or inhibit. A population pharmacokinetic meta-analysis was conducted using individual participant data from 10 studies with 6,100 lumefantrine concentrations from 793 nonpregnant adult participants (41% HIV-malaria-coinfected, 36% malaria-infected, 20% HIV-infected, and 3% healthy volunteers). Lumefantrine exposure increased 3.4-fold with coadministration of lopinavir-ritonavir-based antiretroviral therapy (ART), while it decreased by 47% with efavirenz-based ART and by 59% in the patients with rifampin-based antituberculosis treatment. Nevirapine- or dolutegravir-based ART and malaria or HIV infection were not associated with significant effects. Monte Carlo simulations showed that those on concomitant efavirenz or rifampin have 49% and 80% probability of day 7 concentrations <200 ng/ml, respectively, a threshold associated with an increased risk of treatment failure. The risk of achieving subtherapeutic concentrations increases with larger body weight. An extended 5-day and 6-day artemether-lumefantrine regimen is predicted to overcome these drug-drug interactions with efavirenz and rifampin, respectively.

ABCG2 Deficiency Does Not Alter Dolutegravir Metabolism and Pharmacokinetics

Dolutegravir (DTG) is a potent integrase inhibitor of human immunodeficiency virus. Because DTG is a substrate of the efflux transporter ABCG2 and ABCG2 is highly polymorphic, we asked whether dose adjustment of DTG is needed for ABCG2-deficient individuals. Using Abcg2-null mice, the current work investigated the impact of ABCG2 deficiency on DTG metabolism and pharmacokinetics. Compared with wild-type mice, no statistically significant difference was found in the systemic and tissue-specific (liver, kidney, and brain) pharmacokinetics of DTG in Abcg2-null mice. In addition, ABCG2 deficiency had no statistically significant impact on the production and excretion of DTG metabolites. In summary, this study demonstrated that deficiency of ABCG2 does not alter DTG metabolism and pharmacokinetics, suggesting that dose adjustment of DTG is not needed for individuals with ABCG2 deficiency. SIGNIFICANCE STATEMENT: The current work demonstrated that deficiency of ATP-binding cassette subfamily G member 2 (ABCG2) does not alter Dolutegravir (DTG) metabolism and pharmacokinetics, suggesting that dose adjustment of DTG is not needed for individuals with ABCG2 deficiency.

Psychiatric Disorders after Switching to Dolutegravir: A Case Report of a 59-Year-Old Virosuppressed HIV-1 Positive Woman

We report a case of a woman who experienced psychiatric disorders after switching her antiretroviral therapy (c-ART) to dolutegravir (DTG). She is a 59-year-old HIV-1 positive woman with a recent story of cardiovascular disorders treated with beta-blockers, clopidogrel, and rosuvastatin. She underwent a c-ART switch from darunavir/cobicistat and maraviroc to emtricitabine/tenofovir alafenamide fumarate in association with dolutegravir due to drug-drug interactions. One week later, she started to show psychiatric symptoms that required admission to the psychiatric unit. These disorders resolved within a couple of days after DTG discontinuation to allow a regular discharge. With this case-report, we would like to analyse the possible correlation between integrase inhibitor and severe psychiatric disorders in order to confirm the evidences already published in literature.

Pharmacokinetics, Placental and Breast Milk Transfer of Antiretroviral Drugs in Pregnant and Lactating Women Living with HIV

BACKGROUND

Remarkable progress has been achieved in the identification of HIV infection in pregnant women and in the prevention of vertical HIV transmission through maternal antiretroviral treatment (ART) and neonatal antiretroviral drug (ARV) prophylaxis in the last two decades. Millions of women globally are receiving combination ART throughout pregnancy and breastfeeding, periods associated with significant biological and physiological changes affecting the pharmacokinetics (PK) and pharmacodynamics (PD) of ARVs. The objective of this review was to summarize currently available knowledge on the PK of ARVs during pregnancy and transport of maternal ARVs through the placenta and into the breast milk. We also summarized main safety considerations for in utero and breast milk ARVs exposures in infants.

METHODS

We conducted a review of the pharmacological profiles of ARVs in pregnancy and during breastfeeding obtained from published clinical studies. Selected maternal PK studies used a relatively rich sampling approach at each ante- and postnatal sampling time point. For placental and breast milk transport of ARVs, we selected the studies that provided ratios of maternal to the cord (M:C) plasma and breast milk to maternal plasma (M:P) concentrations, respectively.

RESULTS

We provide an overview of the physiological changes during pregnancy and their effect on the PK parameters of ARVs by drug class in pregnancy, which were gathered from 45 published studies. The PK changes during pregnancy affect the dosing of several protease inhibitors during pregnancy and limit the use of several ARVs, including three single tablet regimens with integrase inhibitors or protease inhibitors co-formulated with cobicistat due to suboptimal exposures. We further analysed the currently available data on the mechanism of the transport of ARVs from maternal plasma across the placenta and into the breast milk and summarized the effect of pregnancy on placental and of breastfeeding on mammal gland drug transporters, as well as physicochemical properties, C:M and M:P ratios of individual ARVs by drug class. Finally, we discussed the major safety issues of fetal and infant exposure to maternal ARVs.

CONCLUSIONS

Available pharmacological data provide evidence that physiological changes during pregnancy affect maternal, and consequently, fetal ARV exposure. Limited available data suggest that the expression of drug transporters may vary throughout pregnancy and breastfeeding thereby possibly impacting the amount of ARV crossing the placenta and secreted into the breast milk. The drug transporter's role in the fetal/child exposure to maternal ARVs needs to be better understood. Our analysis underscores the need for more pharmacological studies with innovative study design, sparse PK sampling, improved study data reporting and PK modelling in pregnant and breastfeeding women living with HIV to optimize their treatment choices and maternal and child health outcomes.

Genetic influence of ABCG2, UGT1A1 and NR1I2 on dolutegravir plasma pharmacokinetics

Objectives

Dolutegravir has replaced efavirenz as first-line treatment in universal HIV guidelines. We sought to ascertain the contributory effect of SNPs in four key genes linked to dolutegravir disposition (UGT1A1, ABCG2, CYP3A and NR1I2) on plasma dolutegravir pharmacokinetics.

Methods

Paired pharmacogenetic/pharmacokinetic data from 93 subjects were analysed for association using multivariate linear regression.

Results

Co-occurring UGT1*28 and NR1I2 c.63396C&gt;T homozygosity was associated with a 79% increase in AUC0–24 (P = 0.001; 27% if analysed individually), whilst combined ABCG2 c.421C&gt;A and NR1I2 c.63396C&gt;T variants were associated with a 43% increase in Cmax (P = 0.002) and a 39% increase in AUC0–24 (P = 0.002). When analysed individually, homozygosity for the NR1I2 c.63396C&gt;T variant alleles was associated with a 28% increase in Cmax (P = 0.033) and homozygosity for the ABCG2 c.421C&gt;A variant alleles was associated with a 28% increase in Cmax (P = 0.047). The UGT1A1*28 (rs8175347) poor metabolizer status (*28/*28; *28/*37; *37/*37) was individually associated with a 27% increase in AUC0–24 (P = 0.020). The combination of UGT1A1*28 poor metabolizer and UGT1A1*6 intermediate metabolizer statuses correlated with a 43% increase in AUC0–24 (P = 0.023).

Conclusions

This study showed a pharmacogenetic association between dolutegravir pharmacokinetics and variants in the ABCG2, UGT1A1 and NR1I2 genes, particularly when combined. Further research is warranted to confirm these associations in population-specific studies and to investigate their putative relationship with dolutegravir pharmacodynamics.

Assessment of Maternal and Fetal Dolutegravir Exposure by Integrating Ex Vivo Placental Perfusion Data and Physiologically-Based Pharmacokinetic Modeling

Antiretroviral therapy during pregnancy reduces the risk of vertical HIV‐1 transmission. However, drug dosing is challenging as pharmacokinetics (PK) may be altered during pregnancy. We combined a pregnancy physiologically‐based pharmacokinetic (PBPK) modeling approach with data on placental drug transfer to simulate maternal and fetal exposure to dolutegravir (DTG). First, a PBPK model for DTG exposure in healthy volunteers was established based on physiological and DTG PK data. Next, the model was extended with a fetoplacental unit using transplacental kinetics obtained by performing ex vivo dual‐side human cotyledon perfusion experiments. Simulations of fetal exposure after maternal dosing in the third trimester were in accordance with clinically observed DTG cord blood data. Furthermore, the predicted fetal trough plasma concentration (C_trough) following 50 mg q.d. dosing remained above the concentration that results in 90% of viral inhibition. Our integrated approach enables simulation of maternal and fetal DTG exposure, illustrating this to be a promising way to assess DTG PK during pregnancy.

Cohort profile: The Observational cohort for the study of DOlutegravir in Antiretroviral Combination REgimens (ODOACRE)

PURPOSE

The Observational cohort for the study of DOlutegravir in Antiretroviral Combination REgimens (ODOACRE) cohort was established in Italy in 2016 to evaluate the overall efficacy and tolerability of dolutegravir (DTG)-based antiretroviral (ARV) regimens in clinical practice.

PARTICIPANTS

The ODOACRE cohort enrols all adult HIV-1-infected patients, both treatment-naïve and treatment-experienced, starting a DTG-based ARV regimen, in 11 clinical centres in Italy from 2014.

FINDINGS TO DATE

In recent years, various works by the ODOACRE cohort have been produced, demonstrating the high efficacy and tolerability of DTG-based ARV regimens in clinical practice, both in ART-naïve (in the setting of acute HIV-1 infection and late presenters patient) and experienced patients. We confirmed the virological efficacy of DTG-based regimens and we evaluated predictors of virological failure. We investigated cause of discontinuation and evaluated tolerability and metabolic profile of the regimens. Within these investigations, we explored particularly the use of DTG in simplification in two-drug regimen with either rilpivirine or lamivudine. We also compared DTG-based regimens with other integrase inhibitors in clinical practice.

FUTURE PLANS

To continue to study long-term efficacy and tolerability of DTG-based regimens is the purpose of the ODOACRE cohort.

Bioequivalence and Food Effect Assessment of 2 Fixed-Dose Combination Formulations of Dolutegravir and Lamivudine

This single‐dose study evaluated the bioequivalence, food effect, and safety of 2 experimental, 2‐drug, fixed‐dose formulations of 50 mg dolutegravir and 300 mg lamivudine (formulation AH and formulation AK) as compared with coadministration of single‐entity tablets of 50 mg dolutegravir and 300 mg lamivudine (reference). In fasted subjects, formulation AH lamivudine exposure was similar to the reference; however, dolutegravir exposure was consistently higher in formulation AH, with area under the concentration‐time curve (AUC) and maximum concentration (C_max) approximately 27% to 28% greater than reference. Formulation AK met bioequivalence standards to the reference for dolutegravir (AUC_0‐∞ and C_max) and lamivudine (AUC_0‐∞ and AUC_0‐t) exposure; however, dolutegravir AUC_0‐t and lamivudine C_max were approximately 16% and 32% higher than the reference, respectively. A high‐fat meal increased dolutegravir AUC and C_max by up to 33% and 21%, respectively, and decreased lamivudine C_max by approximately 30%. Both test and reference formulations were well tolerated. The results support further development of formulation AK as a novel, 2‐drug, fixed‐dose combination tablet treatment for patients with HIV.

In vitro-in vivo correlation of the drug-drug interaction potential of antiretroviral HIV treatment regimens on CYP1A1 substrate riociguat

Objectives: Riociguat is a soluble guanylate cyclase stimulator licensed for the treatment of pulmonary arterial hypertension (PAH), a potentially fatal complication of human immunodeficiency virus infection. This study investigated the inhibitory potency of selected antiretroviral regimens on the metabolic clearance of riociguat.Methods: The inhibitory potential of the components of six antiretroviral combinations (ATRIPLA® (efavirenz/emtricitabine/tenofovir disoproxil), COMPLERA® (rilpivirine/emtricitabine/tenofovir disoproxil), STRIBILD® (elvitegravir/cobicistat/emtricitabine/tenofovir disoproxil), TRIUMEQ® (abacavir/dolutegravir/lamivudine), and two ritonavir-boosted regimens) on riociguat metabolism were evaluated in recombinant human CYP1A1 and CYP3A4 as well as in human hepatocytes exhibiting both CYP1A1 and CYP3A4 activity. In vitro-in vivo correlation was performed between calculated and observed increases in riociguat exposure in vivo.Results: Using both in vitro systems, the predicted increase in exposure of riociguat was highest with components of TRIUMEQ® followed by COMPLERA®, ATRIPLA®, STRIBILD®, and the ritonavir-boosted regimens. Further experiments in human hepatocytes confirmed CYP1A1 to be the predominant enzyme in the metabolic clearance of riociguat.Conclusion: Antiretroviral treatment containing the potent CYP1A1 inhibitor abacavir had the greatest impact on riociguat metabolic clearance. The impact of comedications containing only strong CYP3A4 inhibitors e.g. ritonavir was less pronounced, suggesting a benefit of riociguat over PAH-targeting medications with contraindications for use with strong CYP3A4 inhibitors.

Update on HIV integrase inhibitors for the treatment of HIV-1 infection

It has been over 30 years since the first antiretroviral agent was approved for treatment of HIV-1 infection and its impact on morbidity and mortality has been dramatic. However, early treatments were hindered by short- and long-term toxicity, poor tolerability, high pill burden, drug interactions and development of drug resistance. A major breakthrough in HIV therapeutics occurred over a decade ago with a new class of drugs that not only are preferred by HIV treatment guidelines but also are changing the HIV treatment paradigm. This new class of drugs are called HIV-1 integrase strand transfer inhibitors and they have established a role in almost every aspect of HIV treatment.

Long-term data on the efficacy and tolerability of lamivudine plus dolutegravir as a switch strategy in a multi-centre cohort of HIV-1-infected, virologically suppressed patients

BACKGROUND

Results from clinical trials and observational studies suggest that lamivudine plus dolutegravir (3TC+DTG) could be an effective and tolerated option for simplification in human immunodeficiency virus (HIV)-1-positive patients.

MATERIALS AND METHODS

This observational study enrolled HIV-1-infected, virologically suppressed patients switching to 3TC+DTG. Kaplan-Meyer survival analysis was performed to evaluate time to virological failure (VF; defined by a single HIV-RNA determination ≥1000 copies/mL or by two consecutive HIV-RNA determinations ≥50 copies/mL) and time to treatment discontinuation (TD; defined as interruption of either 3TC or DTG), Cox regression was performed to assess predictors, and linear mixed model was performed for repeated measures to measure changes in immunological and metabolic parameters.

RESULTS

Five hundred and fifty-six patients were eligible for analysis. Their median CD4+ count at baseline was 668 cells/mm³ and median time of virological suppression was 88 months. Estimated probabilities of maintaining virological suppression at 96 and 144 weeks of follow-up were 97.5% [standard deviation (SD) 0.8] and 96.5% (SD 1.0), respectively. Years since HIV diagnosis was the only predictor of VF. In patients with time of virological suppression <88 months, the rate of VF was higher in the presence of the M184V mutation. Estimated probabilities of remaining on 3TC+DTG at 96 and 144 weeks of follow-up were 79.2% (SD 1.9) and 75.2% (SD 2.2), respectively. A significant increase in CD4 cell count (+44 cells/mm³, P=0.015), CD4/CD8 ratio (+0.10, P=0.002) and high-density lipoprotein cholesterol (+5.4 mg/dL, P=0.036) was found at 144 weeks of follow-up; meanwhile, total cholesterol (-9.1 mg/dL, P=0.007) and triglycerides (-2.7, P=0.009) decreased significantly.

CONCLUSIONS

These findings confirm the efficacy and tolerability of 3TC+DTG in virologically suppressed patients.

Elucidation of N 1-methyladenosine as a Potential Surrogate Biomarker for Drug Interaction Studies Involving Renal Organic Cation Transporters

Endogenous substrates are emerging biomarkers for drug transporters, which serve as surrogate probes in drug-drug interaction (DDI) studies. In this study, the results of metabolome analysis using wild-type and Oct1/2 double knockout mice suggested that N ¹-methyladenosine (m¹A) was a novel organic cation transporter (OCT) 2 substrate. An in vitro transport study revealed that m¹A is a substrate of mouse Oct1, Oct2, Mate1, human OCT1, OCT2, and multidrug and toxin exclusion protein (MATE) 2-K, but not human MATE1. Urinary excretion accounted for 77% of the systemic elimination of m¹A in mice. The renal clearance (46.9 ± 4.9 ml/min per kilogram) of exogenously given m¹A was decreased to near the glomerular filtration rates by Oct1/2 double knockout or Mate1 inhibition by pyrimethamine (16.6 ± 2.6 and 24.3 ± 0.6 ml/min per kilogram, respectively), accompanied by significantly higher plasma concentrations. In vivo inhibition of OCT2/MATE2-K by a single dose of 7-[(3R)-3-(1-aminocyclopropyl)pyrrolidin-1-yl]-1-[(1R,2S)-2-fluorocyclopropyl]-8-methoxy-4-oxoquinoline-3-carboxylic acid in cynomolgus monkeys resulted in the elevation of the area under the curve of m¹A (1.72-fold) as well as metformin (2.18-fold). The plasma m¹A concentration profile showed low diurnal and interindividual variation in healthy volunteers. The renal clearance of m¹A in younger (21-45 year old) and older (65-79 year old) volunteers (244 ± 58 and 169 ± 22 ml/min per kilogram, respectively) was about 2-fold higher than the creatinine clearance. The renal clearances of m¹A and creatinine were 31% and 17% smaller in older than in younger volunteers. Thus, m¹A could be a surrogate probe for the evaluation of DDIs involving OCT2/MATE2-K. SIGNIFICANCE STATEMENT: Endogenous substrates can serve as surrogate probes for clinical drug-drug interaction studies involving drug transporters or enzymes. In this study, m¹A was found to be a novel substrate of renal cationic drug transporters OCT2 and MATE2-K. N ¹-methyladenosine was revealed to have some advantages compared to other OCT2/MATE substrates (creatinine and N ¹-methylnicotinamide). The genetic or chemical impairment of OCT2 or MATE2-K caused a significant increase in the plasma m¹A concentration in mice and cynomolgus monkeys due to the high contribution of tubular secretion to the net elimination of m¹A. The plasma m¹A concentration profile showed low diurnal and interindividual variation in healthy volunteers. Thus, m¹A could be a better biomarker of variations in OCT2/MATE2-K activity caused by inhibitory drugs.

HIV-1 Tat and opioids act independently to limit antiretroviral brain concentrations and reduce blood-brain barrier integrity

Poor antiretroviral penetration may contribute to human immunodeficiency virus (HIV) persistence within the brain and to neurocognitive deficits in opiate abusers. To investigate this problem, HIV-1 Tat protein and morphine effects on blood-brain barrier (BBB) permeability and drug brain penetration were explored using a conditional HIV-1 Tat transgenic mouse model. Tat and morphine effects on the leakage of fluorescently labeled dextrans (10-, 40-, and 70-kDa) into the brain were assessed. To evaluate effects on antiretroviral brain penetration, Tat+ and Tat- mice received three antiretroviral drugs (dolutegravir, abacavir, and lamivudine) with or without concurrent morphine exposure. Antiretroviral and morphine brain and plasma concentrations were determined by LC-MS/MS. Morphine exposure, and, to a lesser extent, Tat, significantly increased tracer leakage from the vasculature into the brain. Despite enhanced BBB breakdown evidenced by increased tracer leakiness, morphine exposure led to significantly lower abacavir concentrations within the striatum and significantly less dolutegravir within the hippocampus and striatum (normalized to plasma). P-glycoprotein, an efflux transporter for which these drugs are substrates, expression and function were significantly increased in the brains of morphine-exposed mice compared to mice not exposed to morphine. These findings were consistent with lower antiretroviral concentrations in brain tissues examined. Lamivudine concentrations were unaffected by Tat or morphine exposure. Collectively, our investigations indicate that Tat and morphine differentially alter BBB integrity. Morphine decreased brain concentrations of specific antiretroviral drugs, perhaps via increased expression of the drug efflux transporter, P-glycoprotein.

Simultaneous determination of intracellular concentrations of tenofovir, emtricitabine, and dolutegravir in human brain microvascular endothelial cells using liquid chromatography-tandem mass spectrometry (LC-MS/MS)

Combination antiretroviral therapy (cART) regimens are recommended for HIV patients to better achieve and maintain plasma viral suppression. Despite adequate plasma viral suppression, HIV persists inside the brain, which is, in part thought to result from poor brain penetration of antiretroviral drugs. In this study, a simple and ultra-sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for simultaneous determination of tenofovir, emtricitabine, and dolutegravir in cell lysates of an immortalized human brain microvascular endothelial cell line (hCMEC/D3) was developed and validated. Analytes were separated on a reverse phase C18 column using water and 0.1% formic acid in acetonitrile as mobile phases. The analytes were detected using positive electrospray ionization mode with multiple reaction monitoring (MRM). The assay was linear in the concentration range of 0.1-100 ng mL-1 for all analytes. Intra- and inter-assay precision and accuracy were within ±13.33% and ±10.53%, respectively. This approach described herein was used to determine the intracellular accumulation of tenofovir, emtricitabine, dolutegravir simultaneously in hCMEC/D3 cells samples.