Safety, Tolerability, and Pharmacokinetics of Raltegravir After Single and Multiple Doses in Healthy Subjects

Effects of different integrase strand transfer inhibitors on body weight in patients with HIV/AIDS: a network meta-analysis

Background

Global antiretroviral therapy has entered a new era. Integrase strand transfer inhibitor (INSTI) has become the first choice in acquired immunodeficiency syndrome (AIDS) treatment. Because INSTI has high antiviral efficacy, rapid virus inhibition, and good tolerance. However, INSTIs may increase the risk of obesity. Each INSTI has its unique impact on weight gain in patients with human immunodeficiency virus (HIV)/AIDS. This study systematically assessed different INSTIs in causing significant weight gain in HIV/AIDS patients by integrating data from relevant literature.

Methods

PubMed, Embase, Cochrane Library, China National Knowledge Infrastructure (CNKI), Chinese Biomedical Literature Database (CBM), China Science and Technology Journal Database (VIP), and Wanfang databases were searched to find studies on the influence of different INSTIs in weight gain. Data on weight change were extracted, and a network meta-analysis was performed.

Results

Eight studies reported weight changes in HIV/AIDS patients were included. Results of the network meta-analysis showed that the weight gain of HIV/AIDS patients treated with Dolutegravir (DTG) was significantly higher than that of Elvitegravir (EVG) [MD = 1.13, (0.18–2.07)]. The consistency test results showed no overall and local inconsistency, and no significant difference in the results of the direct and indirect comparison was detected (p > 0.05). The rank order of probability was DTG (79.2%) > Bictegravir (BIC) (77.9%) > Raltegravir (RAL) (33.2%) > EVG (9.7%), suggesting that DTG may be the INSTI drug that causes the most significant weight gain in HIV/AIDS patients.

Conclusion

According to the data analysis, among the existing INSTIs, DTG may be the drug that causes the most significant weight gain in HIV/AIDS patients, followed by BIC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-022-07091-1.

Biorelevant in vitro Tools and in silico Modeling to Assess pH-Dependent Drug-drug Interactions for Salts of Weak Acids: Case Example Potassium Raltegravir

BACKGROUND

Early assessment of pH-dependent drug-drug-interactions (DDIs) for salts of poorly soluble weakly acidic compounds offers various advantages for patient safety, the pharmaceutical industry, and regulatory bodies. Biorelevant media and tests reflecting physiological changes during acid-reducing agent (ARA) co-administration can be used to explore and predict the extent of the pH effect during therapy with ARAs.

METHODS

Solubility, one-stage and two-stage dissolution of tablets containing potassium raltegravir, the marketed salt form of this poorly soluble, weakly acidic drug, was investigated using biorelevant media specially designed to reflect administration without and during ARA co-therapy. The dissolution data were then converted into parameters suitable for input into an in silico model (Simcyp™) and the simulated plasma profiles were compared with available pharmacokinetic (PK) data from the literature.

RESULTS

Dissolution of the potassium raltegravir formulation in media reflecting ARA co-administration, and thus elevated gastric pH, was faster and more complete than in experiments reflecting the low gastric pH observed in the absence of ARA co-administration. Simulations using data from dissolution experiments with ARA media appropriately bracketed the in vivo data for ARA co-administration in healthy volunteers.

CONCLUSION

Dissolution data from in vitro experiments in biorelevant media reflecting physiological changes due to ARA co-administration provide valuable information about potassium raltegravir's behavior during concomitant ARA therapy. The approach may also be suitable for salts forms of other poorly soluble, weakly acidic drugs.

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.

Forgiveness of Dolutegravir-Based Triple Therapy Compared With Older Antiretroviral Regimens: A Prospective Multicenter Cohort of Adherence Patterns and HIV-RNA Replication

Background

For many people with HIV (PWH), taking antiretroviral therapy (ARV) every day is difficult.

Methods

Average adherence (Av-Adh) and log-transformed treatment interruption (TI) to ARV were prospectively measured over 6 months using electronic drug monitoring (EDM) in several cohorts of PWH. Multivariate linear regression models including baseline confounders explored the influence of EDM-defined adherence (R ²) on 6-month log₁₀ HIV-RNA. Multivariate logistic regression models were used to compare the risk of HIV-RNA detection (VR) within subgroups stratified by lower (≤95%) and higher (>95%) Av-Adh.

Results

Three hundred ninety-nine PWH were analyzed with different ARVs: dolutegravir (n = 102), raltegravir (n = 90), boosted PI (bPI; n = 107), and NNRTI (n = 100). In the dolutegravir group, the influence of adherence pattern measures on R ² for HIV-RNA levels was marginal (+2%). Av-Adh, TI, and Av-Adh × TI increased the R ² for HIV-RNA levels by 54% and 40% in the raltegravir and bPI treatment groups, respectively. TI increased the R ² for HIV-RNA levels by 36% in the NNRTI treatment group. Compared with the dolutegravir-based regimen, the risk of VR was significantly increased for raltegravir (adjusted odds ratio [aOR], 45.6; 95% CI, 4.5-462.1; P = .001), NNRTIs (aOR, 24.8; 95% CI, 2.7-228.4; P = .005), and bPIs (aOR, 28.3; 95% CI, 3.4-239.4; P = .002) in PWH with Av-Adh ≤95%. Among PWH with >95% Av-Adh, there were no significant differences in the risk of VR among the different ARVs.

Conclusions

These findings support the concept that dolutegravir in combination with 2 other active ARVs achieves greater virological suppression than older ARVs, including raltegravir, NNRTI, and bPI, among PWH with lower adherence.

When special populations intersect with drug-drug interactions: Application of physiologically-based pharmacokinetic modeling in pregnant populations

Pregnancy results in significant physiological changes that vary across trimesters and into the postpartum period, and may result in altered disposition of endogenous substances and drug pharmacokinetics. Pregnancy represents a unique special population where physiologically-based pharmacokinetic modeling (PBPK) is well suited to mechanistically explore pharmacokinetics and dosing paradigms without subjecting pregnant women or their fetuses to extensive clinical studies. A critical review of applications of pregnancy PBPK models (pPBPK) was conducted to understand its current status for prediction of drug exposure in pregnant populations and to identify areas of further expansion. Evaluation of existing pPBPK modeling efforts highlighted improved understanding of cytochrome P450 (CYP)-mediated changes during pregnancy and identified knowledge gaps for non-CYP enzymes and the physiological changes of the postpartum period. Examples of the application of pPBPK beyond simple dose regimen recommendations are limited, particularly for prediction of drug-drug interactions (DDI) or differences between genotypes for polymorphic drug metabolizing enzymes. A raltegravir pPBPK model implementing UGT1A1 induction during the second and third trimesters of pregnancy was developed in the current work and verified against clinical data. Subsequently, the model was used to explore UGT1A1-related DDI risk with atazanavir and rifampicin along with the effect of enzyme genotype on raltegravir apparent clearance. Simulations of pregnancy-related induction of UGT1A1 either exacerbated UGT1A1 induction by rifampicin or negated atazanavir UGT1A1 inhibition. This example illustrated the advantages of pPBPK modeling for mechanistic evaluation of complex interplays of pregnancy- and drug-related effects in support of model-informed approaches in drug development.

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.

Simulation of oral absorption from non-bioequivalent dosage forms of the salt of raltegravir, a poorly soluble acidic drug, using a physiologically based biopharmaceutical modeling (PBBM) approach

Non-bioequivalent plasma concentration profiles among different dosage forms of the salt of raltegravir, a poorly soluble acidic drug, were investigated using biorelevant in vitro testing combined with the commercial in silico software, Simcyp®. A suspension and a tablet dosage forms of raltegravir potassium were selected as the test formulations. While dissolution from the suspension was rapid, dissolution from the tablets was slow and delayed by pre-exposure to an acidic environment. Although the tablet was expected to have complex in vivo performance, plasma concentration profiles were successfully simulated when gastric emptying was taken into account as a key physiological factor in in vitro and in silico trials. The effect of pre-exposure to acid in the stomach on dissolution behavior in the intestine was estimated by two-stage in vitro dissolution testing. Based on these results, theoretical in vivo dissolution profiles for different gastric emptying times were inputted into the in silico model and plasma concentration profiles were simulated taking the distribution of individual gastric emptying times into account. The in vitro and in silico method presented in this report would be a practical approach to simulate oral absorption from various formulations of poorly soluble weak acids and their salts.

Effect of Pregnancy on Unbound Raltegravir Concentrations in the ANRS 160 RalFe Trial

A population pharmacokinetic model was developed to explore the pharmacokinetics modification of unbound raltegravir during pregnancy. The RalFe ANRS160 study was a nonrandomized, open-label, multicenter trial enrolling HIV-infected pregnant women receiving a combined antiretroviral regimen containing 400 mg raltegravir twice daily. Biological samples were collected during the third trimester of pregnancy (between 30 and 37 weeks of gestational age) and at postpartum (4 to 6 weeks after delivery). A population pharmacokinetic model was developed with Monolix software. A total of 360 plasma samples were collected from 43 women during pregnancy and postpartum. The unbound raltegravir was described by a one-compartment model with a transit compartment with first-order absorption, evolving to bound raltegravir (by a linear binding to albumin) or metabolism to RAL-glucuronide or to a first-order elimination, with a circadian rhythm. During pregnancy, the absorption was decreased and delayed and the raltegravir elimination clearance and glucuronidation increased by 37%. Median total and unbound area under the curve from 0 to 12 h significantly decreased by 36% and 27% during pregnancy. Median total trough concentration (C _trough) decreased significantly in the evening (28%); however, the median total C _trough in the morning, unbound C _trough in the morning, and unbound C _trough in the evening showed a nonsignificant decrease of 16%, 1%, and 15%, respectively, during pregnancy compared to the postpartum period. This is the first study reporting the pharmacokinetics of unbound raltegravir during pregnancy. As unbound C _trough did not significantly decrease during the third trimester, the pregnancy effect on raltegravir unbound concentrations was not considered clinically relevant. (This study has been registered at ClinicalTrials.gov under identifier NCT02099474.).

Predictive Value of Microdose Pharmacokinetics

Phase 0 microdose trials are exploratory studies to early assess human pharmacokinetics of new chemical entities, while limiting drug exposure and risks for participants. The microdose concept is based on the assumption that microdose pharmacokinetics can be extrapolated to pharmacokinetics of a therapeutic dose. However, it is unknown whether microdose pharmacokinetics are actually indicative of the pharmacokinetics at therapeutic dose. The aim of this review is to investigate the predictive value of microdose pharmacokinetics and to identify drug characteristics that may influence the scalability of these parameters. The predictive value of microdose pharmacokinetics was determined for 46 compounds and showed adequate predictability for 28 of 41 orally administered drugs (68%) and 15 of 16 intravenously administered drugs (94%). Microdose pharmacokinetics were considered predictive if the mean observed values of the microdose and the therapeutic dose were within twofold. Nonlinearity may be caused by saturation of enzyme and transporter systems, such as intestinal and hepatic efflux and uptake transporters. The high degree of success regarding linear pharmacokinetics shows that phase 0 microdose trials can be used as an early human model for determination of drug pharmacokinetics.

The crosstalk between antiretrovirals pharmacology and HIV drug resistance

INTRODUCTION

The clinical development of antiretroviral drugs has been followed by a rapid and concomitant development of HIV drug resistance. The development and spread of HIV drug resistance is due on the one hand to the within-host intrinsic HIV evolutionary rate and on the other to the wide use of low genetic barrier antiretrovirals.

AREAS COVERED

We searched PubMed and Embase on 31 January 2020, for studies reporting antiretroviral resistance and pharmacology. In this review, we assessed the molecular target and mechanism of drug resistance development of the different antiretroviral classes focusing on the currently approved antiretroviral drugs. Then, we assessed the main pharmacokinetic/pharmacodynamic of the antiretrovirals. Finally, we retraced the history of antiretroviral treatment and its interconnection with antiretroviral worldwide resistance development both in , and middle-income countries in the perspective of 90-90-90 World Health Organization target.

EXPERT OPINION

Drug resistance development is an invariably evolutionary driven phenomenon, which challenge the 90-90-90 target. In high-income countries, the antiretroviral drug resistance seems to be stable since the last decade. On the contrary, multi-intervention strategies comprehensive of broad availability of high genetic barrier regimens should be implemented in resource-limited setting to curb the rise of drug resistance.

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.

An HIV-infected Patient with No Serious Adverse Events after Overdosing on Raltegravir

Patients with HIV infection represent a high-risk group for medication overdose because of the high frequency of complicating psychiatric disorders. Raltegravir is well-known for its low frequency of adverse effects. We herein report a 42-year-old Japanese man with HIV infection who was hospitalized 6 hours after overdosing with 24,000 mg of raltegravir in a suicide attempt. No serious adverse events occurred, although the plasma concentration of raltegravir at 18 hours after the overdose was 79,871.1 ng/mL. Raltegravir may be well-indicated for HIV patients at risk of overdosing.

Perspectives on the Barrier to Resistance for Dolutegravir + Lamivudine, a Two-Drug Antiretroviral Therapy for HIV-1 Infection

In HIV-1-infected patients, virological failure can occur as a consequence of the mutations that accumulate in the viral genome that allow replication to continue in the presence of antiretrovirals (ARVs). The development of treatment-emergent resistance to an ARV can limit a patient's options for future therapy, prompting the need for ARV regimens that are resilient to the emergence of resistance. The genetic barrier to resistance refers to the number of mutations in an ARV's therapeutic target that are required to confer a clinically meaningful loss of susceptibility to the drug. The emergence of resistance can be affected by pharmacological aspects of the ARV, including its structure, inhibitory quotient, therapeutic index, and pharmacokinetic characteristics. Dolutegravir (DTG) has demonstrated a high barrier to resistance, including when used in a two-drug regimen (2DR) with lamivudine (3TC). In the GEMINI-1 and GEMINI-2 studies, DTG +3TC was noninferior to DTG + emtricitabine/tenofovir disoproxil fumarate in treatment-naive participants, with similar proportions achieving HIV-1 RNA <50 copies/mL through 96 weeks. Furthermore, in the TANGO study, virological suppression was maintained at 48 weeks after switching to DTG +3TC from a tenofovir alafenamide (TAF)-based regimen compared with continuing a TAF-based regimen. Most other 2DRs with successful outcomes compared with three-drug regimens have been based on protease inhibitors (PIs); however, this class is associated with adverse metabolic effects and drug–drug interactions. In this review, we discuss the barrier to resistance in the context of a 2DR in which a boosted PI is replaced with DTG +3TC.

No overall change in the rate of weight gain after switching to an integrase-inhibitor in virologically suppressed adults with HIV

OBJECTIVE

Excessive weight gain has been reported with integrase strand transfer inhibitors (INSTIs). We evaluated weight changes in virologically suppressed adults with HIV who switched from non-INSTI regimens to raltegravir (RAL)-containing or dolutegravir (DTG)-containing antiretroviral therapy.

DESIGN

Retrospective single-centre cohort.

METHODS

Adults who switched to RAL or DTG before or between January 2015 and October 2017 were identified. Virologically suppressed, treatment-experienced (≥2 years) individuals, at least 6 months on INSTI, with weight measurements 2 years or less pre and postswitch were included. Our analysis used a random effects model with linear slope pre and post-INSTI with adjustment for age, sex, ethnicity, preswitch-regimen (protease inhibitor vs. nonprotease inhibitor), and RAL vs. DTG use.

RESULTS

A total of 378 individuals, 81.2% male, 70.1% white ethnicity, median age of 49 years, median of four weight measurements per participant, and median weight and BMI at switch of 76.6 kg and 25.3 kg/m, respectively, were included. Weight increased by an average of 0.63 kg/year (95% confidence interval 0.17-1.09) preswitch with no overall change in rate of weight gain postswitch [+0.05 kg/year (-0.61-0.71, P = 0.88)]. In our adjusted model, a transition from minimal weight change to weight gain postswitch was isolated to older individuals though this lacked statistical significance [e.g., +1.59 kg/year (-0.26-3.45) if aged 65 years]. Our findings did not differ by sex, ethnicity, preswitch regimen, or RAL vs. DTG. Similar results were seen for BMI and after adjusting for fixed nucleoside/nucleotide reverse transcriptase inhibitor backbone.

CONCLUSION

We found no clear evidence of an overall increase in rate of weight gain following switch to INSTI in virologically suppressed individuals.

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.

No recovery of replication-competent HIV-1 from human liver macrophages

Long-lived HIV-1 reservoirs that persist despite antiretroviral therapy (ART) are a major impediment to a cure for HIV-1. We examined whether human liver macrophages (LMs), the largest tissue macrophage population, comprise an HIV-1 reservoir. We purified LMs from liver explants and included treatment with a T cell immunotoxin to reduce T cells to 1% or less. LMs were purified from 9 HIV-1-infected persons, 8 of whom were on ART (range 8-140 months). Purified LMs were stimulated ex vivo and supernatants from 6 of 8 LMs from persons on ART transmitted infection. However, HIV-1 propagation from LMs was not sustained except in LMs from 1 person taking ART for less than 1 year. Bulk liver sequences matched LM-derived HIV-1 in 5 individuals. Additional in vitro experiments undertaken to quantify the decay of HIV-1-infected LMs from 3 healthy controls showed evidence of infection and viral release for prolonged durations (>170 days). Released HIV-1 propagated robustly in target cells, demonstrating that viral outgrowth was observable using our methods. The t1/2 of HIV-1-infected LMs ranged from 3.8-55 days. These findings suggest that while HIV-1 persists in LMs during ART, it does so in forms that are inert, suggesting that they are defective or restricted with regard to propagation.

Precision medicine for HIV: where are we?

To date, antiretroviral therapy is highly effective in HIV-affected patients, but the individualization of such a life-long therapy may be advised. This review briefly summarizes the main factors involved in the potential personalization of antiretroviral treatment. Relevant articles in English were identified by PubMed and recent congresses’ abstracts. Foremost influences concerning pharmacodynamics, therapeutic drug monitoring, pharmacogenetics, comorbidities, immune recovery and viral characteristics affecting the healthcare of HIV-positive patients are listed here. Furthermore, pharmacoeconomic aspects are mentioned. Applying pharmacokinetic and pharmacogenetic knowledge may be informative and guide the better choice of treatment in order to achieve long-term efficacy and avoid adverse events. Randomized investigations of the clinical relevance of tailored antiretroviral regimens are needed in order to obtain a better management of HIV/AIDS-affected patients.

Prevention and treatment of HIV infection in neonates: evidence base for existing WHO dosing recommendations and implementation considerations

INTRODUCTION

Antiretroviral drugs are used in neonates for prevention and treatment of HIV infection. Use of antiretrovirals to prevent perinatal HIV transmission is well established. Early identification of neonates infected with HIV and rapid initiation of combination antiretroviral treatment during the neonatal period is now recommended by WHO and DHHS. However, few antiretrovirals are available in formulations suitable for neonates and there are limited safety and pharmacokinetic data for most antiretrovirals in neonates. Areas covered: We summarize existing neonatal antiretroviral safety and pharmacokinetic information and discuss implementation considerations for programs providing antiretrovirals to neonates and young infants. Expert commentary: Antiretrovirals currently recommended by WHO for use in neonates are zidovudine, lamivudine, lopinavir/ritonavir, nevirapine, and raltegravir. Significant implementation challenges exist to the widespread use of these antiretrovirals in neonates. Optimal, feasible treatment of HIV-exposed and HIV-infected newborns will require development of practical neonatal dosage forms and their study in neonates for a wide range of antiretrovirals.

Hemeoxygenase-1 as a Novel Driver in Ritonavir-Induced Insulin Resistance in HIV-1-Infected Patients

BACKGROUND

Hemeoxygenase-1 (HO-1) has recently been identified as a major driver of metaflammation and obesity-related insulin resistance (IR). Drug-induced IR increases cardiovascular risk within the HIV-1-infected population receiving antiretroviral therapy (ART). We therefore investigated a possible role of HO-1 in ART-induced IR.

METHODS

Effects of HIV-1 protease inhibitor ritonavir and integrase inhibitor raltegravir (RAL) on expression levels of HO-1 and proinflammatory cytokines, including interleukin 1β (IL-1β), IL-6, IL-8, tumor necrosis factor-α (TNFα), chemokine (C-C motif) ligand 5 (CCL5), and monocyte chemotactic protein 1 (MCP-1), were studied in monocyte and hepatocyte cell lines. Plasma levels of HO-1 and inflammatory markers were measured in insulin-resistant and insulin-sensitive HIV-1-infected patients under ART and seronegative controls.

RESULTS

We show that, in contrast to RAL, ritonavir treatment significantly increases mRNA expression levels of HO-1, IL-8, TNFα, CCL5, and MCP-1 in vitro in a dose-dependent manner. HO-1 plasma levels were significantly higher in insulin-resistant compared to insulin-sensitive patients on ritonavir-boosted ART (lopinavir/ritonavir group: 3.90 ± 1.15 vs 2.56 ± 1.07 ng/mL, P < 0.005 and darunavir/ritonavir group: 3.16 ± 1.37 vs 2.28 ± 1.23 U/mL, P < 0.05) and were correlated with expression levels of TNFα in individuals on ritonavir-boosted ART (lopinavir/ritonavir group: r = 0.108, P < 0.05 and darunavir/ritonavir group: r = 0.221, P < 0.05) but not in HIV-1-infected individuals receiving RAL or in seronegative controls.

IMPLICATIONS

HIV-1-infected patients on stable ART are often faced with non-AIDS-related metabolic comorbidities, increasing their individual cardiovascular risk. Here, we provide insight into a novel mechanism of ritonavir-induced IR involving proinflammatory properties of HO-1. Our initial observations might also provide prognostic value in the future to identify patients at risk for the development type 2 diabetes mellitus.

Cervicovaginal and Rectal Fluid as a Surrogate Marker of Antiretroviral Tissue Concentration: Implications for Clinical Trial Design

BACKGROUND

Quantifying tissue drug concentrations can yield important information during drug development, but complicates pharmacokinetic study design. Mucosal fluids collected by direct aspiration (cervicovaginal fluid; CVF) or swab (rectal fluid; RF) might be used as tissue concentration surrogates, but these relationships are not well characterized.

METHODS

Forty-nine healthy women, given a single oral dose of tenofovir, maraviroc, emtricitabine, or raltegravir at 50%-200% of the treatment dose, provided 13 plasma, 12 CVF, 12 RF and one cervical, vaginal and rectal tissue biopsy over 48 hours. Relationships between these paired samples were characterized by linear and multiple linear regression. Adjusted r values were used to select the final predictive models.

RESULTS

CVF exposure increased linearly with dose for all antiretrovirals (r(2) ≥ 0.23, P ≤ 0.02) except raltegravir (r(2) = 0.08, P = 0.19). In RF, only emtricitabine increased linearly with dose (r(2) = 0.27, P = 0.01). For all antiretrovirals, CVF and RF concentrations significantly correlated with mucosal tissue concentrations (female genital tract r(2) ≥ 0.37, rectal tissue (2)r ≥ 0.50, P ≤ 0.001). In the final multivariate models, plasma and fluid concentrations were both associated with FGT concentrations for all antiretrovirals (r(2) ≥ 0.81, P < 0.001). The same was noted for rectal tissue (r(2) ≥ 0.58, P < 0.001) except for tenofovir, for which RF alone was predictive of tissue concentration (r(2) = 0.91, P < 0.001).

CONCLUSIONS

Mucosal fluids were positively correlated with tissue concentrations and including plasma concentrations improved the regression models in most cases. Dose linearity in CVF, but not RF, suggests a saturation process in lower gastrointestinal tract tissue. These findings suggest that mucosal fluid and plasma concentrations may be used for qualitative inference of tissue concentrations for these antiretrovirals.

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.

Antiretroviral drug toxicity in relation to pharmacokinetics, metabolic profile and pharmacogenetics

INTRODUCTION

Besides therapeutic effectiveness, drug tolerability is a key issue for treatments that must be taken indefinitely. Given the high prevalence of toxicity in HIV therapy, the factors implicated in drug-induced morbidities should be identified in order to improve the safety, tolerability and adherence to the treatments. Current approaches have focused almost exclusively on parent drug concentrations; whereas recent evidence suggests that drug metabolites resulting from complex genetic and environmental influences can also contribute to treatment outcome. Pharmacogenetic variations have shown to play a relevant role in the variability observed in antiretroviral drug exposure, clinical response and sometimes toxicity. The integration of pharmacokinetic, pharmacogenetic and metabolic determinants will more probably address current therapeutic needs in patients.

AREAS COVERED

This review offers a concise description of three classes of antiretroviral drugs. The review looks at the metabolic profile of these drugs and gives a comprehensive summary of the existing literature on the influence of pharmacogenetics on their pharmacokinetics and metabolic pathways, and the associated drug or metabolite toxicity.

EXPERT OPINION

Due to the high prevalence of toxicity and the related risk of low adherence to the treatments, association of kinetic, genetic and metabolic markers predictive of therapeutic or toxicity outcomes could represent a more complete approach for optimizing antiretroviral therapy.

Mucosal tissue pharmacokinetics of the integrase inhibitor raltegravir in a humanized mouse model: Implications for HIV pre-exposure prophylaxis

Orally administered anti-retroviral drugs show considerable promise for HIV/AIDS pre-exposure prophylaxis (PrEP). For the success of these strategies, pharmacokinetic (PK) data defining the optimal concentration of the drug needed for protection in relevant mucosal exposure sites is essential. Here we employed a humanized mouse model to derive comprehensive PK data on the HIV integrase inhibitor raltegravir (RAL), a leading PrEP drug candidate. Under steady state conditions following oral dosing, plasma and multiple mucosal tissues were sampled simultaneously. RAL exhibited higher drug exposure in mucosal tissues relative to that in plasma with one log higher exposure in vaginal and rectal tissue and two logs higher exposure in intestinal mucosa reflecting the trends seen in the human studies. These data demonstrate the suitability of RAL for HIV PrEP and validate the utility of humanized mouse models for deriving important preclinical PK-PD data.

RTG-loaded nanomicelles (CS–VES–NAC) for oral anti-HIV drug delivery

An acetylcysteine–chitosan–vitamin E succinate copolymer (CVN) was synthesized from chitosan (CS), vitamin E succinate (VES) and N-acetyl-l-cysteine (NAC) as self-assembled nanomicelles for multifunctional delivery of anti-HIV drug Raltegravir (RTG).

Pharmacokinetics and 48-Week Safety and Efficacy of Raltegravir for Oral Suspension in Human Immunodeficiency Virus Type-1-Infected Children 4 Weeks to 2 Years of Age

BACKGROUND

IMPAACT P1066 is a Phase I/II open-label multicenter trial to evaluate safety, tolerability, pharmacokinetics (PK), and efficacy of multiple raltegravir (RAL) formulations in human immunodeficiency virus (HIV)-infected youth.

METHODS

Dose selection of the oral suspension formulation for each cohort (IV: 6 months to <2 years and V: 4 weeks to <6 months) was based on review of short-term safety (4 weeks) and intensive PK evaluation. Safety data through Weeks 24 and 48 and Grade ≥3 or serious adverse events (AEs) were assessed. The primary virologic endpoint was achieving HIV RNA <400 copies/mL or ≥1 log10 reduction from baseline at Week 24 (Success). For Cohort IV, optimized background therapy (OBT) could have been initiated with RAL either at study entry or after intensive PK sampling was completed at Day 5-12. An OBT was started when RAL was initiated for Cohort V subjects because they were not permitted to have received direct antiretroviral therapy before enrollment.

RESULTS

Total accrual was 27 subjects in these 2 cohorts, including 1 subject who was enrolled but never started study drug (excluded from the analyses). The targeted PK parameters (area under the curve [AUC]0-12hr and C12hr) were achieved for each cohort allowing for dose selection. Through Week 48, there were 10 subjects with Grade 3+ AEs. Two were judged related to study drug. There was 1 discontinuation due to an AE of skin rash, 1 event of immune reconstitution syndrome, and no drug-related deaths. At Week 48, for Cohorts IV and V, 87.5% of subjects achieved virologic success and 45.5% had HIV RNA <50 copies/mL. At Week 48, gains in CD4 cells of 527.6 cells/mm(3) and 7.3% were observed.

CONCLUSIONS

A total of 6 mg/kg per dose twice daily of RAL for oral suspension was well tolerated and showed favorable virologic and immunologic responses.

Raltegravir Pharmacokinetics in Patients on Asunaprevir-Daclatasvir

Raltegravir pharmacokinetics was studied in 20 patients included in the ANRS HC30 QUADRIH Study before and after addition of anti-hepatitis C virus (anti-HCV) quadritherapy, including pegylated-interferon-ribavirin and asunaprevir plus daclatasvir. Raltegravir pharmacokinetic parameters remained unchanged whether administered on or off anti-HCV therapy. In addition, concentrations of raltegravir, asunaprevir, and daclatasvir were not affected by liver cirrhosis. These data suggest that in human immunodeficiency virus (HIV)-HCV-coinfected patients, whether cirrhotic or not, asunaprevir and daclatasvir could be administered safely with raltegravir.

The preclinical discovery and development of dolutegravir for the treatment of HIV

INTRODUCTION

Integration of the viral genome into the host cell chromatin is a central step in the replication cycle of HIV. Blocking the viral integrase (IN) enzyme therefore provides an attractive therapeutic strategy, as evidenced by the recent clinical approval of three IN strand transfer inhibitors. Dolutegravir is a therapy that is unique in its ability to evade HIV drug resistance in treatment-naïve patients.

AREAS COVERED

This review starts by providing a brief summary of the history of HIV-1 IN inhibitors. The authors follow this with details of the discovery and preclinical and clinical developments of dolutegravir. Finally, the authors provide details of dolutegravir's post-launch including the launch of the combination pill of dolutegravir, abacavir and lamivudine in August 2014.

EXPERT OPINION

The launch of raltegravir, the first IN inhibitor from Merck & Co., has created new hopes for the patient. Indeed, pharmaceutical companies have not lost courage by attempting to address the major drawbacks of this first-in-class molecule. And while the drug elvitegravir has been inserted into a four-drug combination pill providing a once-daily dosing alternative, dolutegravir has demonstrated superiority in terms of its efficacy and resistance.

Comparison of the pharmacokinetics of raltegravir given at 2 doses of 400 mg by swallowing versus one dose of 800 mg by chewing in healthy volunteers: a randomized, open-label, 2-period, single-dose, crossover phase 1 study

BACKGROUND

The pharmacokinetics of raltegravir (RAL) in HIV patients is characterized by high interindividual and intraindividual variability. We documented previously that HIV patients taking RAL at 400 mg bid by chewing the tablets had significantly higher drug absorption and reduced pharmacokinetic variability than patients taking the drug by swallowing the tablets. This study extends our previous findings.

METHODS

An open-label, 2-period crossover study compared the pharmacokinetics of 2 doses of RAL given at 400 mg every 12 hours (that mimics a bid administration) by swallowing with 1 dose of 800 mg (that mimics a qd administration) by chewing the tablets in 12 healthy volunteers. RAL plasma concentrations were measured by a chromatographic method coupled with mass spectrometry.

RESULTS

Subjects taking RAL by chewing had significantly higher drug exposure (RAL area under the curve[AUC](0-24): 40722 ± 14843 versus 21753 ± 12229 ng · h/mL, P < 0.0001) and reduced pharmacokinetic variability compared with those taking the drug by swallowing the whole tablet, with no difference in the minimum RAL concentrations (RAL C(min): 36 ± 23 versus 43 ± 23 ng/mL, P = 0.298). Subjects taking RAL by chewing the tablets had significantly higher drug absorption and reduced pharmacokinetic variability compared with those taking the drug by swallowing. No differences were observed in the minimum RAL concentrations.

CONCLUSIONS

RAL at 800 mg once daily by chewing the tablets may represent a novel therapeutic option for the treatment of HIV being associated with higher drug absorption, reduced pharmacokinetic variability, and potentially better compliance compared with patients swallowing the 400-mg bid intact tablets.

Pharmacokinetic determinants of virological response to raltegravir in the in vitro pharmacodynamic hollow-fiber infection model system

Daily administration (q24h) of raltegravir has been shown to be as efficacious as twice-daily administration (q12h) in the hollow-fiber infection model (HFIM) system. However, q24h regimens were not noninferior to q12h dosing in a clinical trial. We hypothesized that between-patient variability in raltegravir pharmacokinetics (PK) was responsible for the discordance in conclusions between the in vitro and in vivo studies. Hollow-fiber cartridges were inoculated with HIV-infected H9 cells and uninfected CEM-SS cells. Four cartridges received the total daily exposure (800 mg) q24h and four received half the daily exposure (400 mg) q12h. PK profiles with half-lives of 8, 4, 3, and 2 h were simulated for each dosing interval. Cell-to-cell viral spread was assessed by flow cytometry. Viral inhibition was similar between q24h and q12h dosing at the 8- and 4-h half-lives. The q24h dosing was not as efficacious as the q12h dosing when faster half-lives were simulated; a lack of viral suppression was observed at days 3 and 4 for the 2- and 3-h half-lives, respectively. The discrepancy in conclusions between the in vitro HFIM system studies and clinical trials is likely due to the large interindividual variation in raltegravir PK.

Population pharmacokinetic analysis of raltegravir pediatric formulations in HIV-infected children 4 weeks to 18 years of age

P1066 is an open-label study of raltegravir in HIV positive youth, ages 4 weeks-18 years. Here we summarize P1066 pharmacokinetic (PK) data and a population PK model for the pediatric chewable tablet and oral granules. Raltegravir PK parameters were calculated using noncompartmental analysis. A 2-compartment model was developed using data from P1066 and an adult study of the pediatric formulations. Interindividual variability was described by an exponential error model, and residual variability was captured by an additive/proportional error model. Twelve-hour concentrations (C12h ) were calculated from the model-derived elimination rate constant and 8-hour observed concentration. Simulated steady-state concentrations were analyzed by noncompartmental analysis. Target area under the curve (AUC0-12h ) and C12h were achieved in each cohort. For the pediatric formulations, geometric mean AUC0-12h values were 18.0-22.6 μM-hr across cohorts, and C12h values were 71-130 nM, with lower coefficients of variation versus the film-coated tablet. A 2-compartment model with first-order absorption adequately described raltegravir plasma PK in pediatric and adult patients. Weight was a covariate on clearance and central volume and was incorporated using allometric scaling. Raltegravir chewable tablets and oral granules exhibited PK parameters consistent with those from prior adult studies and older children in P1066, as well as lower variability than the film-coated tablet.

Raltegravir pharmacokinetics in neonates following maternal dosing

: International Maternal Pediatric Adolescent AIDS Clinical Trials P1097 was a multicenter trial to determine washout pharmacokinetics and safety of in utero/intrapartum exposure to raltegravir in infants born to HIV-infected pregnant women receiving raltegravir-based antiretroviral therapy. Twenty-two mother-infant pairs were enrolled; evaluable pharmacokinetic data were available from 19 mother-infant pairs. Raltegravir readily crossed the placenta, with a median cord blood/maternal delivery plasma raltegravir concentration ratio of 1.48 (range, 0.32-4.33). Raltegravir elimination was highly variable and extremely prolonged in some infants; [median t1/2 26.6 (range, 9.3-184) hours]. Prolonged raltegravir elimination likely reflects low neonatal UGT1A1 enzyme activity and enterohepatic recirculation. Excessive raltegravir concentrations must be avoided in the neonate because raltegravir at high plasma concentrations may increase the risk of bilirubin neurotoxicity. Subtherapeutic concentrations, which could lead to inadequate viral suppression and development of raltegravir resistance, must also be avoided. Two ongoing International Maternal Pediatric Adolescent AIDS Clinical Trials studies are further investigating the pharmacology of raltegravir in neonates.

Optimizing antiretroviral therapy for women living with HIV

PURPOSE OF REVIEW

This review considers the evidence available to guide clinicians in their choice of optimal antiretroviral therapy (ART) for women with HIV.

RECENT FINDINGS

Cohort and clinical trial data indicate that ART is as efficacious in women as men, although women are more likely to discontinue therapy, which compromises effectiveness. For many drugs, women have higher plasma levels than men, although whether this is secondary to differing metabolism in women or because on average women have a lower body mass than men is not clear. For many drugs, women experience more adverse events secondary to ART. Opinion on the use of efavirenz in pregnancy differs between countries. The average age of women with HIV is increasing. Although virological responses to ART are not affected by age, immunological responses may be poorer. Older women with HIV face issues such as neurocognitive impairment, early menopause, osteoporosis and polypharmacy, which will have the potential to impact on their use of ART.

SUMMARY

When planning ART regimes with women, clinicians need to be mindful of the woman's social situation and stage in the life course, as well as the scientific data on individual drug effectiveness according to sex.

Long-term efficacy and safety of raltegravir in the management of HIV infection

Raltegravir is an integrase strand-transfer inhibitor approved for the treatment of HIV infection. It was the first medication in a novel class of antiretroviral agents to be approved for use in the United States in 2007. Raltegravir exhibits potent activity against wild-type HIV-1, but resistance development has been noted through three different pathways. It is metabolized primarily through uridine diphosphate glucuronosyltransferase 1A1 and has a single inactive glucuronide metabolite. Raltegravir is not a substrate, inhibitor, or inducer of cytochrome P450 enzymes and exhibits low potential for drug–drug interactions; however, strong uridine diphosphate glucuronosyltransferase 1A1 inhibitors or inducers can alter the pharmacokinetics of raltegravir. It is well tolerated, and the most commonly reported adverse effects include headache, nausea, and diarrhea. Serious adverse effects with raltegravir are rare but include rhabdomyolysis and severe skin and hypersensitivity reactions. It has been approved for use in both treatment-naïve and treatment-experienced patients and is a preferred first-line agent in both United States and European HIV treatment guidelines. Although initial approval was granted on 48-week data, 5-year clinical data have recently been published. This article reviews the data supporting long-term efficacy and safety of raltegravir in the treatment of HIV infection.

Pharmacokinetic study of dual therapy with raltegravir 400 mg twice daily and Darunavir/Ritonavir 800/100 mg once daily in HIV-1-infected patients

BACKGROUND

Combinations of new classes of antiretroviral drugs are attractive options to avoid toxicity associated with nucleoside reverse transcriptase inhibitors (NRTIs) and to provide a full active regimen in patients with some degree of resistance to NRTIs. However, data on the pharmacokinetic (PK) profiles of these regimens are limited. We explore the plasma PK profile of raltegravir (RAL) at a dose of 400 mg twice a day plus darunavir/ritonavir (DRV/RTV) at a dose of 800/100 mg once a day in HIV-1-infected patients.

METHODS

This was a pilot, open-label, fixed-sequence, prospective, single-center single-arm PK study. The treating physician chose an NRTI-sparing regimen because of toxicity or resistance mutations to NRTIs, which included DRV/RTV 800/100 mg once daily plus RAL 400 mg twice daily. All patients were RAL and DRV naive and had no evidence of protease inhibitor mutations. After at least 15 days on therapy, patients were admitted for a 24-hour PK study. Laboratory tests to assess efficacy and safety were performed at all study visits.

RESULTS

Fifteen patients were included. The geometric mean values for DRV were AUC0-24 68,730 ng·h·mL [95% confidence interval (CI): 58,970-86,480], Ctrough 1330 ng/mL (95% CI: 1110-1760; IC-50 for wild-type and resistant HIV-1 strains was 55 and 550 ng/mL, respectively), Cmax 7630 ng/mL (95% CI: 6740-9000), and t1/2 10.9 hours (95% CI: 9.20-13.99). Geometric mean values for RAL were AUC0-12 3050 ng·h·mL (95% CI: 2530-5180); Ctrough 40 ng/mL (95% CI: 30-80), Cmax 970 ng/mL (95% CI: 840-2270), t1/2 2.68 hours (95% CI: 1.97-4.40). No adverse effects including rash or laboratory test abnormalities were noted. At week 24, the HIV-1 viral load was below 37 copies/mL in all patients.

CONCLUSIONS

Our data suggest that dual therapy with RAL 400 mg twice daily plus DRV/RTV 800/100 mg once daily had a favorable PK profile for both drugs and that short-term efficacy and tolerability of this combination were adequate.

Hepatic safety and tolerability of raltegravir among HIV patients coinfected with hepatitis B and/or C

BACKGROUND

Potential liver toxicity is an important consideration for antiretroviral selection among patients coinfected with HIV and viral hepatitis (B and/or C). We sought to describe the hepatic safety profile of raltegravir in this population.

METHODS

Using data from HIV clinical cohorts at Johns Hopkins University and the University of North Carolina at Chapel Hill, we evaluated factors associated with liver enzyme elevations (LEEs) and calculated adverse event incidence rates for patients initiated on raltegravir-containing regimens prior to 1 January 2010. LEEs were graded according to Division of AIDS definitions.

RESULTS

During the study period, 456 patients received raltegravir - of whom 36% were hepatitis-coinfected (138 HCV, 17 HBV, 11 HBV+HCV). Coinfected patients were more likely to have baseline abnormal LEEs and developed severe (grade 3-4) LEEs at a rate 3.4× that of HIV-monoinfected patients (95% CI 1.28, 9.61). Among all participants, the incidence rate for first occurrence of severe LEEs was 5 per 100 person-years (95% CI 3, 7). In adjusted analyses, coinfected patients had a 2.7-fold increased hazard of severe LEEs (95% CI 1.03, 7.04). 60% of severe abnormalities occurred within 6 months after starting raltegravir; the drug was discontinued in 3 (1.3%) coinfected patients and 18 (6.2%) monoinfected patients.

CONCLUSIONS

Compared with HIV-monoinfected patients, those with HIV-hepatitis coinfection are at increased hazard of developing LEEs on raltegravir, at a level similar to other antiretrovirals. Severe events were uncommon, rarely leading to raltegravir discontinuation. With appropriate monitoring, raltegravir-based therapy is safe in hepatitis-coinfected patients.

Validation of an UPLC-MS/MS method for quantitative analysis of raltegravir in human plasma samples

BACKGROUND

An ultra-performance liquid chromatography-tandem mass spectrometry method was developed for the quantification of raltegravir (RTG) plasma concentrations in samples from HIV patients treated with the drug.

METHODS

Plasma samples were extracted by liquid-liquid extraction followed by evaporation to dryness and reconstitution in mobile phase. The chromatographic separation was carried out on an AQUITY UPLC C18 column with an isocratic mobile phase consisting of water containing 0.1% formic acid and acetonitrile containing 0.1% formic acid (50:50 vol/vol). The detection was performed on a triple quadrupole tandem mass spectrometer using multi-reaction monitoring via electrospray ionization source with positive ionization mode.

RESULTS

Under these conditions, a single chromatographic run could be completed within 1 minute. The method was validated by estimating the precision and the accuracy for inter- and intra-day analysis in the concentration range of 5-2560 ng/mL. The method was linear over the investigated range with all the correlation coefficients, r, greater than 0.995 on 5 replicates. The intra- and inter-day precision (percentage of coefficient of variation) ranged from 2.4% to 11.2%, and the inaccuracy (percent of relative standard deviation) ranged from 2.5% to 12.9%. No significant matrix effect was observed. The mean recovery value of RTG was 80%.

CONCLUSIONS

This rapid and sensitive method was validated and could be applied to pharmacokinetic studies for the determination of RTG concentrations in human plasma samples.

Dolutegravir: a new integrase strand transfer inhibitor for the treatment of HIV

The first two integrase strand transfer inhibitors (INSTIs) approved for treatment of patients infected with human immunodeficiency virus (HIV) were raltegravir and elvitegravir. Both raltegravir and elvitegravir are now guideline-preferred agents as part of an antiretroviral regimen for treatment-naive patients. However, raltegravir is dosed twice/day. Elvitegravir is available in a single-tablet regimen and dosed once/day because it is administered with the pharmacokinetic booster cobicistat, a potent CYP3A4 inhibitor that can lead to clinically significant drug-drug interactions. In addition, raltegravir and elvitegravir have a low genetic barrier to resistance and are associated with cross-resistance. Dolutegravir is a new-generation INSTI administered once/day without a pharmacokinetic booster and can be coformulated in a single-tablet regimen. Phase III studies have demonstrated the efficacy and safety of dolutegravir for treatment-naive and treatment-experienced patients. Compared with other INSTIs, dolutegravir has a higher genetic barrier to resistance. Dolutegravir was approved by the U.S. Food and Drug Administration in August 2013 and joins raltegravir and elvitegravir as guideline-preferred agents for the management for HIV-infected treatment-naive patients.

One-month transplacental pharmacokinetics of raltegravir in a premature newborn after short-course treatment of the HIV-1-infected mother

We describe the pharmacokinetics of raltegravir of a preterm newborn after short-course treatment of the mother tested HIV + the day of delivery. At age 1 month, the circulating concentration of raltegravir in the newborn was 29 ng/ml (the IC95 of RAL against HIV-1 is 15 ng/ml). Raltegravir should therefore be considered a potential transplacental postexposure prophylaxis for HIV-1 and an alternative to the use of boosted lopinavir in this context.

Variability of raltegravir plasma levels in the clinical setting

Therapeutic drug monitoring of raltegravir Ctrough levels was carried out in the setting of the Raltegravir Switch for Toxicity or Adverse events (RASTA) trial, a randomized pilot study exploring a 48-week safety and efficacy of treatment switch to raltegravir associated with tenofovir/emtricitabine or abacavir/lamivudine in patients with regimens with optimal virologic control. Blood sampling for measurement of raltegravir plasma levels was carried out at weeks 4, 12, 24, 36 and 48. Plasma samples were analysed by a recently developed and validated UPLC-MS method. A total of 164 samples from 39 patients were assayed. Analysis for intra- and inter-subject variability was restricted to those patients with 4 or more determinations, including 30 patients and 142 determinations. The intra- and inter-subject variability measures were 85.9 and 124.6%, respectively, with an intra-/inter-subject variability ratio of 69%. We also analysed data from a subset of patients with well-documented adherence to protocol, defined as protocol compliant population, including 21 patients and 93 determinations. In this subpopulation, we estimated intra- and inter-subject variability of 79.87% and 110%, respectively, with an intra-/inter-subject variability ratio of 72.6%. This study confirms the notion that raltegravir is a highly variable drug according to the European Medicines Agency criteria. While this condition does not favour the adoption of therapeutic drug monitoring in the clinical practice, the latter is deemed useful in patients with drug plasma concentrations below or near the threshold level of efficacy (since intracellular raltegravir levels might be as low as 5% of the corresponding plasma levels), or to identify drug-drug interactions of potential clinical relevance.