Pharmacokinetics of Single-Dose Dolutegravir in HIV-Seronegative Subjects With Moderate Hepatic Impairment Compared to Healthy Matched Controls

Relative Bioavailability of Dolutegravir (DTG) and Emtricitabine/Tenofovir Alafenamide Fumarate (F/TAF) Administered as Paediatric Tablet Formulations in Healthy Volunteers

BACKGROUND AND OBJECTIVE

Within the UNIVERSAL project (RIA2019PD-2882) we aim to develop a paediatric dolutegravir (DTG)/emtricitabine (FTC or F)/tenofovir alafenamide (TAF) fixed-dose combination. To inform dosing of this study, we undertook a relative bioavailability (RBA) study in healthy volunteers to investigate a potential pharmacokinetic effect when paediatric formulations of DTG and F/TAF are taken together.

METHODS

Participants received all of the following treatments as paediatric formulations in randomised order: a single dose of 180/22.5 mg F/TAF; a single dose of 30 mg DTG; a single dose of 180/22.5 mg F/TAF plus 30 mg DTG. Blood concentrations of DTG, FTC, TAF, and tenofovir (TFV) were measured over 48 h post-dose. If the 90% confidence intervals (CIs) of the geometric least squares mean (GLSM) ratios of area under the curve (AUC) and maximum concentration (Cmax) of each compound were within 0.70-1.43, we considered this as no clinically relevant PK interaction.

RESULTS

A total of 15 healthy volunteers were included. We did not observe a clinically relevant PK interaction between the paediatric DTG and F/TAF formulations for the compounds DTG, FTC, and TFV. For TAF, the lower boundaries of the 90% CIs of the GLSM ratios of the AUC0-∞ and Cmax fell outside our acceptance criteria of 0.70-1.43.

CONCLUSIONS

Although TAF AUC and Cmax 90% CIs fell outside the pre-defined criteria (0.62-1.11 and 0.65-1.01, respectively), no consistent effect on TAF PK was observed, likely due to high inter-subject variability. Moreover, there are several reasons to rely on TFV exposure as being more clinically relevant than TAF exposure. Therefore, we found no clinically relevant interactions in this study.

Intramuscular cabotegravir and rilpivirine concentrations after switching from efavirenz-containing regimen

AIMS

Intramuscular cabotegravir/rilpivirine (IM CAB/RPV) are metabolized by UGT1A1/CYP3A4. Efavirenz induces both enzymes; therefore, switching from an efavirenz-containing regimen to IM CAB/RPV could possibly result in suboptimal levels. Due to their long dosing interval, clinical studies with IM CAB/RPV are challenging. We used physiologically based pharmacokinetics (PBPK) modelling to simulate the switch from efavirenz to IM CAB/RPV.

METHODS

First, we developed the drug models and verified the performance of the PBPK model to predict the pharmacokinetics of IM cabotegravir, IM rilpivirine and efavirenz by comparing the simulations against observed clinical data. Second, we verified the ability of the model to predict the effect of residual induction with observed data for the switch from efavirenz to dolutegravir or rilpivirine. Finally, we generated a cohort of 100 virtual individuals (20-50 years, 50% female, 18.5-30 kg/m2 ) to simulate IM CAB/RPV concentrations after discontinuing efavirenz in extensive and slow metabolizers of efavirenz.

RESULTS

IM CAB concentrations were predicted to decrease by 11% (95% confidence interval 7-15%), 13% (6-21%) and 8% (0-18%) at day 1, 7 and 14 after efavirenz discontinuation. CAB concentrations were predicted to remain above the minimal efficacy threshold (i.e., 664 ng/mL) throughout the switch period both in extensive and slow metabolizers of efavirenz. Similarly, IM RPV concentrations were modestly decreased with the lowest reduction being 10% (6-14%) on day 7 post last efavirenz dose.

CONCLUSION

Our simulations indicate that switching from an efavirenz-containing regimen to IM CAB/RPV does not put at risk of having a time window with suboptimal drug levels.

Clinical Relevance of Drug Interactions in People Living with Human Immunodeficiency Virus on Antiretroviral Therapy-Update 2022: Systematic Review

BACKGROUND

The clinical outcomes of antiretroviral drugs may be modified through drug interactions; thus, it is important to update the drug interactions in people living with HIV (PLHIV).

AIM

To update clinically relevant drug interactions in PLHIV on antiretroviral therapy with novel drug interactions published from 2017 to 2022.

METHODS

A systematic review in Medline/PubMed database from July 2017 to December 2022 using the Mesh terms antiretroviral agents and drug interactions or herb-drug interactions or food-drug interactions. Publications with drug interactions in humans, in English or Spanish, and with full-text access were retrieved. The clinical relevance of drug interactions was grouped into five levels according to the gravity and probability of occurrence.

RESULTS

A total of 366 articles were identified, with 219 (including 87 citation lists) were included, which allowed for the identification of 471 drug interaction pairs; among them, 291 were systematically reported for the first time. In total 42 (14.4%) and 137 (47.1%) were level one and two, respectively, and 233 (80.1%) pairs were explained with the pharmacokinetic mechanism. Among these 291 pairs, protease inhibitors (PIs) and ritonavir/cobicistat-boosted PIs, as well as integrase strand transfer inhibitors (InSTIs), with 70 (24.1%) and 65 (22.3%) drug interaction pairs of levels one and two, respectively, were more frequent.

CONCLUSIONS

In PLHIV on antiretroviral therapy, we identify 291 drug interaction pairs systematically reported for the first time, with 179 (61.5%) being assessed as clinically relevant (levels one and two). The pharmacokinetic mechanism was the most frequently identified. PIs, ritonavir/cobicistat-boosted PIs, and InSTIs were the antiretroviral groups with the highest number of clinically relevant drug interaction pairs (levels one and two).

Pharmacokinetic and pharmacokinetic/pharmacodynamic characterization of the dolutegravir/rilpivirine two-drug regimen in SWORD-1/-2 phase 3 studies

AIM

SWORD-1 and SWORD-2 phase 3 studies concluded that switching virologically suppressed participants with HIV-1 from their current three- or four-drug antiretroviral regimen (CAR) to the two-drug regimen of once-daily dolutegravir (DTG, 50 mg) and rilpivirine (RPV, 25 mg) was safe, well tolerated and noninferior for maintaining HIV-1 suppression at week 48 and highly efficacious to week 148. A secondary objective was to characterize drug exposure and exposure-efficacy/safety relationships.

METHODS

Adults with plasma HIV-1 RNA <50 copies/mL were randomized to switch to once-daily DTG + RPV on day 1 or to continue CAR for 52 weeks before switching. Trough plasma concentrations (C0) of DTG and RPV, the proportion of participants with HIV-1 RNA <50 copies/mL and adverse events to week 100 were summarized and subjected to exposure-response analyses in the overall population, in the subset of participants who switched from CAR containing enzyme-inducing drugs and by age category (≥50 and <50 years). The relationship between C0avg (individual average C0 across visits) and efficacy/safety was investigated.

RESULTS

Although week 2 DTG and RPV C0 were lower in participants switching from enzyme-inducing antiretroviral drugs, C0 and C0avg stayed above in vitro antiviral protein binding-adjusted IC90 and to week 100 with viral suppression >89%. DTG or RPV C0avg showed no relationship with virologic failures or safety. Participants ≥50 years had similar C0avg and safety response to younger participants.

CONCLUSION

No clinically relevant relationship between DTG or RPV exposures and virologic or safety response was observed, confirming the DTG + RPV switch for participants as a safe and effective treatment.

HIV-1 Integrase Strand Transfer Inhibitors and Neurodevelopment

Children born to mothers, with or at risk, of human immunodeficiency virus type-1 (HIV-1) infection are on the rise due to affordable access of antiretroviral therapy (ART) to pregnant women or those of childbearing age. Each year, up to 1.3 million HIV-1-infected women on ART have given birth with recorded mother-to-child HIV-1 transmission rates of less than 1%. Despite this benefit, the outcomes of children exposed to antiretroviral drugs during pregnancy, especially pre- and post- natal neurodevelopment remain incompletely understood. This is due, in part, to the fact that pregnant women are underrepresented in clinical trials. This is underscored by any potential risks of neural tube defects (NTDs) linked, in measure, to periconceptional usage of dolutegravir (DTG). A potential association between DTG and NTDs was first described in Botswana in 2018. Incidence studies of neurodevelopmental outcomes associated with DTG, and other integrase strand transfer inhibitors (INSTIs) are limited as widespread use of INSTIs has begun only recently in pregnant women. Therefore, any associations between INSTI use during pregnancy, and neurodevelopmental abnormalities remain to be explored. Herein, United States Food and Drug Administration approved ARVs and their use during pregnancy are discussed. We provide updates on INSTI pharmacokinetics and adverse events during pregnancy together with underlying mechanisms which could affect fetal neurodevelopment. Overall, this review seeks to educate both clinical and basic scientists on potential consequences of INSTIs on fetal outcomes as a foundation for future scientific investigations.

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.

Dolutegravir impairs stem cell-based 3D morphogenesis models in a manner dependent on dose and timing of exposure: an implication for its developmental toxicity

Dolutegravir is an anti-retroviral drug of the integrase strand transfer inhibitor class used to treat HIV infection. It is the recommended first-line regimen for most people, including women of childbearing age. However, some human and animal studies have suggested that dolutegravir causes birth defects, although its developmental toxicity remains controversial. Here, we investigated the adverse effects of dolutegravir using pluripotent stem cell-based in vitro morphogenesis models that have previously been validated as effective tools to assess the developmental toxicity of various chemicals. Dolutegravir diminished the growth and axial elongation of the morphogenesis model of mouse pluripotent stem cells at exposures of 2 μM and above in a concentration-dependent manner. Concomitantly, dolutegravir altered the expression profiles of developmental regulator genes involved in embryonic patterning. The adverse effects were observed when the morphogenesis model was exposed to dolutegravir at early stages of development, but not at later stages. The potency and molecular impact of dolutegravir on the morphogenesis model were distinct from other integrase strand transfer inhibitors. Lastly, dolutegravir altered the growth and gene expression profiles of the morphogenesis model of human embryonic stem cells at 1 μM and above. These studies demonstrate that dolutegravir impairs morphological and molecular aspects of the in vitro morphogenesis models in a manner dependent on dose and timing of exposure through mechanisms that are unrelated to its action as an integrase strand transfer inhibitor. This finding will be useful for interpreting the conflicting outcomes regarding the developmental toxicity of dolutegravir in human and animal studies.

Saliva as a potential matrix for evaluating pharmacologically active dolutegravir concentration in plasma

Therapeutic drug monitoring (TDM) is used in certain clinically selected cases and in research settings to optimize the response to antiretroviral therapy. Plasma of blood is commonly used for TDM, but blood sampling is invasive and at risk for transmission of infectious agents. On the other hand, saliva sampling is noninvasive, safe, cheap, and easily performed compared to blood. Dolutegravir (DTG) is now widely prescribed as a key component of antiretroviral therapy for HIV infection. In this study, we examined the relationship between DTG concentrations in plasma and saliva of treated patients to explore the possibility of using saliva as an alternative body fluid of TDM. A total of 17 pairs of blood and saliva samples were obtained from 15 consented HIV-1-infected subjects treated with DTG containing regimens for more than one month. Both blood and saliva samples were collected within 1 h of each other. Drug concentrations were determined by liquid chromatography-tandem mass spectrometry using DTG-d5 as an internal standard. The LLOQ was 0.5 ng/mL. The calibration curves were prepared with pooled plasma or saliva containing DTG in a range of 0.5–100 ng/mL with precision of <14.4% and accuracy within ±14.7%. The DTG concentrations in the plasma and saliva were significantly correlated (Pearson’s correlation coefficient r = 0.76, p < 0.001). The median ratio of the drug concentration in saliva to those in plasma was 0.0056, which is close to the rate of non-protein-bound DTG in plasma (0.70%), suggesting that only free DTG in plasma is transported to the salivary glands and secreted into saliva. The present study demonstrates that DTG concentration in saliva reflects the pharmacologically active drug concentration in plasma and may provide an easily accessible alternative for monitoring effective antiretroviral treatment.

Development of a simple and rapid method to determine the unbound fraction of dolutegravir, raltegravir and darunavir in human plasma using ultrafiltration and LC-MS/MS

Dolutegravir, raltegravir and darunavir are three antiretroviral drugs widely used in combined antiretroviral therapies. These three drugs are highly bound to plasma proteins. Compared to the total concentration, the concentration of unbound drug which is considered as the only pharmacological active form should be more informative to improve therapeutic drug monitoring in patients to avoid virological failure or toxicity. The aim of the present study was to develop an ultrafiltration protocol and a LC-MS/MS method to simultaneously determine the concentrations of the unbound dolutegravir, raltegravir and darunavir in human plasma. Finally, 150 μL of plasma was ultrafiltrated using Centrifree® ultrafiltration devices with ultracel YM-T membrane (cutoff 30 KDa) during 5 min at 37 °C at 1500 g. Then, 20 μL of the ultrafiltrate were injected into the LC-MS/MS system. The chromatographic separation was carried out on a BEH C18 column using a mobile phase containing deionized water and acetonitrile, both with 0.05 % (v/v) of formic acid, with a gradient elution at a flow rate of 0.5 mL/min. The run time was only 4 min. The calibration curve ranged from 0.5-200 ng/mL for dolutegravir, 1 to 400 ng/mL for raltegravir and 10-4000 ng/mL for darunavir. This method was validated with a good precision (inter- and intra-day CV% lower than 14 %) and a good accuracy (inter- and intra-day bias between -5.6-8.8 %) for all the analytes. This method is simple, reliable and suitable for pharmacokinetic studies.

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.

The Effect of Moderate- and High-Fat Meals on the Bioavailability of Dolutegravir/Rilpivirine Fixed-Dose Combination Tablet

Dolutegravir 50 mg (DTG) and rilpivirine 25 mg (RPV) are a newly approved 2-drug regimen for the treatment of HIV in virally suppressed patients. A 2-part study evaluated the relative bioavailability and food effect of five experimental fixed-dose combination (FDC) tablet formulations of DTG/RPV. When given with a moderate- or high-fat meal, the absorption of both DTG and RPV was increased, resulting in higher exposures. As per product labelling, DTG/RPV FDC should be taken with a meal.

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.

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.

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.

A Phase 1 Study to Evaluate the Pharmacokinetics and Safety of Cabotegravir in Patients With Hepatic Impairment and Healthy Matched Controls

Cabotegravir is an investigational integrase inhibitor in development for the treatment and pre-exposure prophylaxis of HIV-1 infection. Liver disease is a major cause of morbidity and mortality in HIV-infected individuals and can impact the pharmacokinetics (PK) of HIV medications. This phase 1 study evaluated the PK of cabotegravir in individuals with moderate hepatic impairment (n = 8) versus healthy controls (n = 8). Participants received a single oral cabotegravir 30-mg tablet and underwent PK sampling to determine total and unbound plasma cabotegravir concentrations. Calculated geometric least-squares mean ratios (90% confidence intervals) for individuals with hepatic impairment versus healthy controls were 0.73 (0.50-1.06) for AUC_0-∞ , 0.69 (0.51-0.93) for C_max , 1.40 (0.80-2.46) for unbound concentration (CU) 2 hours postdose, 1.55 (0.82-2.94) for CU at 24 hours, 2.14 (1.57-2.90) for unbound fraction (FU) at 2 hours, and 1.90 (1.14-3.18) for FU at 24 hours. Adverse events (AEs) occurred in 2 individuals with hepatic impairment and 3 healthy controls and were grade 1/2 in severity. No participant discontinued because of AEs. Increased FU resulted in a modest decrease in total plasma exposure not considered clinically relevant. We conclude that cabotegravir may be administered without dose adjustment in patients with mild to moderate hepatic impairment.

The clinical pharmacology of integrase inhibitors

Introduction: Treatment of HIV infection has consistently evolved in the last three decades. A steady improvement in efficacy tolerability, safety, and practical aspects of treatment intake has made HIV infection much easier to manage over the long term, and in optimal treatment conditions the life expectancy of persons living with HIV infection now approaches the values of the general population. The last category of antiretrovirals to be fully developed for clinical use is the one of strand-transfer integrase inhibitors (INSTIs). Areas covered: In this review, the evolution of the knowledge on INSTIs use in the clinical setting is reviewed, analyzed, and interpreted. Emphasis is placed on the properties possibly accounting for several superiority results achieved by INSTIs in non-inferiority designed comparative clinical trials, which led to their inclusion as first line options in all versions of HIV therapeutic guidelines. Expert commentary: Some unprecedented clinical-pharmacological properties of INSTIs, such as their rapid and sustained action against HIV replication, the optimal tolerability and safety profile and a clinically proven robust genetic barrier are the main factors justifying the successful clinical use of INSTIs. Based on these unique features, novel INSTIs-based treatment modalities are being developed, including the reduction of antiretroviral regimens to two drugs only.

Bioequivalence of a Fixed-Dose Combination Tablet of the Complete Two-Drug Regimen of Dolutegravir and Rilpivirine for Treatment of HIV-1 Infection

A complete 2-drug regimen of dolutegravir at 50 mg and rilpivirine at 25 mg was approved to treat HIV-1 infection in virologically suppressed patients after demonstrating acceptable efficacy and tolerability. This study investigated the bioequivalence and pharmacokinetics of the fixed-dose combination tablet compared with those of separate tablets.

A complete 2-drug regimen of dolutegravir at 50 mg and rilpivirine at 25 mg was approved to treat HIV-1 infection in virologically suppressed patients after demonstrating acceptable efficacy and tolerability. This study investigated the bioequivalence and pharmacokinetics of the fixed-dose combination tablet compared with those of separate tablets. Secondary endpoints were the tolerability and safety of the fixed-dose combination tablet. In this open-label, randomized-sequence, 2-way crossover trial, single doses of the fixed-dose combination tablet (the test treatment) and the combination of separate tablets (the reference treatment) were administered to healthy adults after a moderate-fat meal, with a 21-day washout between treatments. Pharmacokinetic samples were collected through 12 days after dosing. The primary endpoints were the area under the plasma concentration-time curve (AUC) and the maximum concentration of drug in plasma (C_max). The study employed a prespecified sample size reestimation based on a blind midpoint review of C_max variability to update the enrollment size to achieve statistical power. Of 118 participants enrolled, 113 received both treatments and underwent pharmacokinetic assessment. The 90% confidence intervals for the geometric least-squares mean ratios for the AUC from 0 h to infinity, the AUC from 0 h to the last quantifiable measurement, and C_max (test treatment versus reference treatment) were within the bioequivalence range of 0.80 to 1.25 for both drugs, indicating bioequivalence. In this study, a single dose of either treatment was well tolerated overall, with 4% (n = 5) and 3% (n = 3) of participants reporting adverse events considered related to the test and reference treatments, respectively. The dolutegravir-rilpivirine fixed-dose combination tablet is bioequivalent to a combination of separate tablets, and no new safety signals emerged. (This study has been registered at ClinicalTrials.gov under identifier NCT02741557.)

High plasma concentrations of dolutegravir in patients with ABCG2 genetic variants

The ATP-binding cassette transporters B1 (ABCB1) and G2 (ABCG2) are both expressed in the intestine and known as efflux transporters of drugs. Dolutegravir was identified recently as a substrate of both ABCB1 and ABCG2. This study aimed to determine the relations between single-nucleotide polymorphisms of ABCB1 and ABCG2 genes and plasma dolutegravir concentrations. Plasma samples were obtained from 42 HIV-1-infected patients treated with dolutegravir-containing regimens 0.5-4 h after dolutegravir dosing. Plasma dolutegravir concentrations were measured by liquid chromatography-mass spectrometry. Genomic DNA was isolated from peripheral blood mononuclear cells. Genotyping of allelic variants of ABCB1 1236 C>T (rs1128503), 2677 G>T/A (rs2032582), 3435 C>T (rs1045642), 4036 A>G (rs3842), and ABCG2 421 C>A (rs2231142) was performed using the TaqMan drug metabolism assays. None of the genotypes in ABCB1 1236 C>T, 2677 G>T/A, 3435 C>T, and 4036 A>G correlated with plasma dolutegravir concentration. In contrast, the mean peak plasma concentration of dolutegravir was significantly higher in the genotypes of ABCG2 421 AA (5002 ng/ml, n=3) compared with the genotypes of ABCG2 421 CC (2569 ng/ml, n=22) and ABCG2 421 CA (2479 ng/ml, n=17) (P=0.0005). The speculated peak level of plasma dolutegravir concentration was significantly higher in ABCG2 genetic variant holders, probably, at least in part, because of low expression levels of efflux transporters in the intestines associated with these genetic variants.

Determination of dolutegravir's unbound fraction in human plasma using validated equilibrium dialysis and LC-MS/MS methods

Assessment of the unbound pharmacologically active fraction (fu; as the ratio of unbound to total concentration) of dolutegravir could improve therapeutic drug monitoring (TDM) in patients that experience virological failure or toxicity, despite receiving adequate total concentrations. This study evaluated (i) dolutegravir's fu through equilibrium dialysis (ED), (ii) the pre-analytical parameters that influence fu, and (iii) fu's inter-individual variability in HIV patients. Validation of the LC-MS/MS method followed FDA guidelines. The results, based on coefficients of variation (results from nominal concentrations <15%), allowed accurate measurement of unbound and total dolutegravir concentrations. Equilibrium during ED was obtained in 4h. Sparse non-specific binding (9%) was observed, allowing results interpretation without interference. Steps before analysis (e.g., conservation at +4°C, freeze/thaw cycles) did not influence fu, allowing easy integration of fu analysis within laboratory routines. Anticoagulants from samples (citrated versus heparinized; p<0.001) and hemolysis (p=0.007) influenced fu and could lead to misinterpretation. Developed was then performed to the HIV-patients' plasma (n=54). Results, expressed as median InterQuartile Range [25%;75%] were 0.45% IQR [0.38; 0.55] for fu, 9.26μg/L IQR [4.62; 15.14] for unbound, and 2035μg/L IQR [878.5; 2640] for total concentration. The high inter-individual variability observed in the unbound form from HIV patients was a first step towards integrating dolutegravir TDM.

Human Immunodeficiency Virus Infection, Antiretroviral Therapy, and Liver Pathology

The improvement in antiretroviral therapy has significantly impacted the lives of people living with human immunodeficiency virus (HIV). In high-income countries, HIV deaths are predominated by liver disease consequent to viral hepatitis coinfection, alcohol, and nonalcoholic fatty liver disease. Published liver pathology findings have shifted from being predominated by opportunistic infections to the metabolic effects of HIV and antiretroviral therapy as well as drug-induced liver injuries. Differences remain between high-income and low-income countries, where opportunistic infections and immune reconstitution syndromes, dominate findings.

Relative Bioavailability of a Dolutegravir Dispersible Tablet and the Effects of Low- and High-Mineral-Content Water on the Tablet in Healthy Adults

Dolutegravir (DTG) is approved in the United States to treat HIV‐1‐infected patients weighing ≥30 kg. A dispersible DTG tablet formulation was recently developed for pediatric patients. This study compares the pharmacokinetics (PK) of the dispersible tablet with that of a previously evaluated granule formulation. In this randomized, open‐label, crossover study, 15 healthy adults received single oral doses of DTG 20 mg every 7 days across 5 treatment arms: granules consumed immediately after mixture with purified water, dispersible DTG consumed immediately after reconstitution in low‐mineral‐content (LMC) or high‐mineral‐content (HMC) water, and dispersible DTG consumed 30 minutes after dispersal in LMC or HMC water. Primary endpoints were bioavailability of immediately consumed dispersible tablet in LMC water relative to granule formulation reconstituted in purified water and PK of the dispersible tablet. Secondary endpoints included tolerability and palatability. The DTG dispersible tablet showed equivalent exposures to the granule formulation with geometric least‐squares mean treatment ratios of 1.06 and 1.12 for AUC_0‐∞ and C_max, respectively. DTG PK parameters were unaffected by mineral content or the 30‐minute delay. Adverse events were mild; only nausea (n = 1) was considered drug related. DTG exposure observed with the dispersible tablet supports evaluation of this formulation for further development.

Comparative Clinical Pharmacokinetics and Pharmacodynamics of HIV-1 Integrase Strand Transfer Inhibitors

Dolutegravir (DTG), elvitegravir (EVG) and raltegravir (RAL) are members of the latest class of antiretrovirals (ARVs) that have become available to treat human immunodeficiency virus (HIV) infection: integrase strand transfer inhibitors (INSTIs). INSTIs are potent inhibitors of the HIV integrase enzyme, with protein binding-adjusted concentration inhibiting viral replication by 90/95 % [IC90/95] values in the low nanogram per millilitre range, and they retain antiviral activity against strains of HIV with acquired resistance to other classes of ARVs. Each of the INSTIs has unique pharmacokinetic/pharmacodynamic properties, influencing its role in clinical use in specific subsets of patients. RAL and DTG have minimal drug-drug interaction profiles, as their metabolism has minimal cytochrome P450 (CYP) involvement. Conversely, EVG metabolism occurs primarily via CYP3A4 and requires pharmacokinetic boosting to achieve systemic exposures amenable to once-daily dosing. EVG and DTG have the added benefit of availability of fixed-dose combination tablets, allowing for convenient and simplified ARV regimens. RAL is the only INSTI to be listed as a preferred agent in the current US perinatal treatment guidelines. All three INSTIs are recommended regimens for treatment-naïve individuals in the US adult and adolescent HIV treatment guidelines. This review summarizes and compares the pharmacokinetics and pharmacodynamics of the INSTIs, and describes specific pharmacokinetic considerations for special patient conditions: hepatic impairment, renal dysfunction, pregnancy and co-infections.

Dolutegravir - a review of the pharmacology, efficacy, and safety in the treatment of HIV

Dolutegravir is the newest integrase strand transfer inhibitor to be approved for the treatment of human immunodeficiency virus (HIV) infection. Dolutegravir is equivalent or superior to existing treatment regimens in both treatment-naïve and treatment-experienced patients including those with previous raltegravir or elvitegravir failure. The consistent efficacy coupled with excellent tolerability and infrequent drug–drug interactions makes the co-formulation of dolutegravir with two nucleotide reverse-transcriptase inhibitors an attractive treatment option. This review summarizes the pharmacokinetics, adverse event profile, and efficacy of dolutegravir in the treatment of HIV.

Dolutegravir: a review of its use in the management of HIV-1 infection in adolescents and adults

Dolutegravir (Tivicay(®)) is a new-generation HIV-1 integrase strand transfer inhibitor recently approved in the EU and Japan for the treatment of HIV-1 infection in adolescents and adults in combination with other antiretroviral drugs. It is suitable for once-daily administration and achieves therapeutic concentrations without the need for pharmacokinetic boosting. It has a high barrier to resistance and is generally active against viral strains resistant to first-generation integrase inhibitors. In well-designed clinical trials in treatment-naive or treatment-experienced, integrase inhibitor-naive patients, dolutegravir-based combinations were shown to be noninferior or superior to raltegravir-based combinations, an efavirenz-based combination and ritonavir-boosted darunavir-based combinations with respect to virological suppression (plasma HIV-1 RNA <50 copies/mL) at week 48. Dolutegravir was also effective in a high proportion of patients failing on raltegravir- or elvitegravir-based therapy as a result of integrase resistance mutations. Dolutegravir was generally well tolerated, with the vast majority of adverse events being mild or moderate in intensity; serious adverse events were uncommon. Therefore, dolutegravir is an important new addition to the expanding list of antiretroviral drugs for treating HIV-1 infection in adults and adolescents.

The role of dolutegravir in the management of HIV infection

Dolutegravir is the most recent integrase strand transfer inhibitor approved for HIV-1 infection in both treatment-naïve and experienced patients. As a tricyclic carbamoyl pyridone analog, dolutegravir is rapidly absorbed and distributes through the cerebrospinal fluid. It is hepatically metabolized by uridine diphosphate glucuronosyl transferase 1A1; no inhibition or induction of cytochrome P450 enzymes is noted. As a substrate of CYP 3A4, dolutegravir is affected by rifampin, efavirenz, tipranavir/ritonavir, fosamprenavir/ritonavir, and dose increase is required. Dolutegravir inhibits the organic cation transporter 2, resulting in decreased creatinine clearance with no apparent decrease in renal function. Other adverse effects are minimal but include diarrhea, headache, and nausea. Clinical trials in treatment-naïve and experienced patients are ongoing and will be presented in this text.

Dolutegravir: An Integrase Strand Transfer Inhibitor for the Treatment of Human Immunodeficiency Virus 1 in Adults

Objective: To review the efficacy, safety, pharmacokinetics, pharmacodynamics, administration, drug interactions, and cost of dolutegravir (Tivicay), a third in class integrase strand transfer inhibitor (INSTI), for the treatment of human immunodeficiency virus (HIV-1) in adults. Data Sources: MEDLINE, International Pharmaceutical Abstracts, ClinicalTrials.gov, and Google Scholar searches (January 2000 to May 2014) were conducted for articles published in English and limited to human subjects, using the key words antiretroviral drugs, HIV integrase strand transfer inhibitors, dolutegravir, DTG, and S/GSK1349572. Study Selection and Data Extraction: Following MEDLINE, International Pharmaceutical Abstracts, ClinicalTrials.gov, and Google Scholar searches, 6 clinical trials were identified and included in this review. Phase III/IV studies evaluating the safety and efficacy of dolutegravir in humans were selected and evaluated. Data Synthesis: In treatment naïve and experienced patients dolutegravir was noninferior to raltegravir at suppressing viral load when added to background therapy. Abacavir/lamivudine/dolutegravir was noninferior to efavirenz/emtricitabine/tenofovir disoproxil fumarate and darunavir/ritonavir plus background therapy at suppressing viral load. In patients with multiple-class antiretroviral resistance at baseline, dolutegravir decreased HIV RNA by 1.4 log10 copies/mL at day 8, 63% of patients had achieved virologic suppression at week 8, and retained potency in treatment-experienced INSTI-resistant patients up to week 48 or 96 of follow-up. Conclusion: Dolutegravir is a safe, effective, and well-tolerated treatment option for adults with HIV-1, even in the setting of resistance to other antiretrovirals.