Pharmacokinetic and safety profile of raltegravir and ribavirin, when dosed separately and together, in healthy volunteers

The Influence of Antiretroviral Therapy on Hepatitis C Virus Viral Load and Liver Fibrosis in Human Immunodeficiency Virus-Coinfected Patients: An Observational Study

BACKGROUND

The role of antiretroviral therapy (ART) for Hepatitis C viral load (HCV-VL) and liver fibrosis is poorly understood. This study aimed at evaluating the influence of ART on HCV-VL and liver fibrosis in human immunodeficiency virus (HIV)/HCV-coinfected patients.

METHODS

We conducted a retrospective cohort study of HIV/HCV-coinfected patients followed at a tertiary university hospital.

RESULTS

In total, 143 patients were included. In 61 patients, ART initiation was accompanied by an increase in HCV-VL and a decrease in HIV viral load (HIV-VL), whereas ART suspension led to a decrease in HCV-VL and an increase in HIV-VL. Among the 55 HIV-suppressed patients who switched to a raltegravir (RAL)-containing regimen, median HCV-VL levels decreased significantly, while switching to a rilpivirine-containing regimen did not yield a significant reduction.

DISCUSSION

If the -treatment of chronic hepatitis starts before ART, ART initiation should be delayed as much as possible. If ART has been started, it is advisable to wait 1 year before initiating chronic hepatitis treatment. RAL as the third agent in an ART regimen could be beneficial in HIV/HCV-coinfected patients, in comparison to other antiretroviral drugs.

CONCLUSION

The start and the suspension of ART significantly interferes with HCV-VL in HIV/HCV-coinfected patients.

Pharmacokinetic profile of raltegravir, elvitegravir and dolutegravir in plasma and mucosal secretions in rhesus macaques

OBJECTIVES

Pharmacokinetic studies in animal models are important for assessing the prophylactic potential of antiretroviral drugs for HIV prevention. This study sought to identify clinically relevant doses of the marketed integrase inhibitors raltegravir, elvitegravir and dolutegravir in macaques and investigate drug penetration and antiviral activity in mucosal secretions.

METHODS

Macaques received one oral dose of raltegravir, elvitegravir or dolutegravir alone or in combination with emtricitabine and tenofovir disoproxil fumarate followed by drug level measurements in blood and rectal and vaginal secretions. Antiviral activity was investigated in TZM-bl cells exposed to SHIV162p3 in the presence of rectal secretions collected from treated animals.

RESULTS

Plasma drug concentrations with 50 mg/kg raltegravir or elvitegravir were within the range seen in humans receiving 400-800 mg of raltegravir or 800 mg of unboosted elvitegravir but lower than with 150 mg of elvitegravir boosted with cobicistat. AUC0-24 values for dolutegravir increased proportionally with the dose, with a calculated human-equivalent dose of 20 mg/kg. Elvitegravir showed the highest penetration in rectal and vaginal fluids despite the absence of pharmacological boosting, followed by raltegravir and dolutegravir. Rectal secretions collected at 24 h from treated macaques blocked infection of TZM-bl cells by 50% at dilutions of 1/1000 (raltegravir), 1/800 (dolutegravir) and >1/30 000 (elvitegravir).

CONCLUSIONS

We defined macaque doses of HIV integrase inhibitors that recapitulate human clinical doses, which will facilitate efficacy and dose escalation studies in macaques. High and sustained drug concentrations and activity in mucosal secretions suggest that integrase inhibitors are promising candidates for HIV prevention.

A switch to Raltegravir improves antiretroviral associated hepatotoxicity in individuals co-infected with HIV and hepatitis C

INTRODUCTION

Raltegravir is a switch option for HIV/HCV co-infected individuals due to its hepatic neutral profile. We evaluated the effect of a switch to Raltegravir from other antiretroviral agents in HIV and HCV-co-infected individuals naïve to HCV therapy.

METHODS

Observational, single-centre study. Data on alanine aminotransferase levels, HCV-VL, CD4 cell count, HIV viral load levels and hepatic fibrosis score were collated six months pre-switch, at the time of switch and six months post switch to Raltegravir therapy. Results were compared utilizing the Kruskal-Wallis test.

RESULTS

Twenty-seven individuals were identified. Median age was 43 years, median duration of HIV infection was 7 years and median documented period of HCV infection at the time of switch was 26 months. A sustained improvement in ALT levels was observed. Median ALT levels were 254 IU/L at the time of switch, decreasing significantly to 176 IU/L, (p = 0.0226) and 90 IU/L (p = 0.0138) 1 month post switch and 6 months post switch respectively. The median Hepatitis C viral load level at the time of the switch was 341,783 copies/mL, which decreased to 224,066 copies/mL 6 months after switch (p = 0.04).

DISCUSSION

A switch to Raltegravir in individuals with HIV/HCV co-infection was effective in maintaining HIV virological suppression with improvement in drug-associated hepatotoxicity as measured by ALT.

Pharmacology of HIV integrase inhibitors

PURPOSE OF REVIEW

The purpose of this study is to review recent and relevant pharmacology data for three HIV integrase inhibitors: raltegravir (marketed), dolutegravir, and elvitegravir (both in phase III drug development).

RECENT FINDINGS

Data from January 2011 to April 2012 were evaluated. These data better characterized integrase inhibitor pharmacokinetics, assessed dosing regimens, and investigated previously undescribed drug-drug interactions. Due to formulation challenges, raltegravir inter-patient and intra-patient pharmacokinetic variability is high. Twice-daily 400  mg dosing has been shown to be clinically superior to 800  mg once-daily dosing. A pediatric formulation of raltegravir with less variable pharmacokinetics and greater bioavailability was US Food and Drug Administration (US FDA)-approved in December 2011. Cobicistat-boosted elvitegravir, and the second-generation integrase inhibitor dolutegravir, have lower pharmacokinetic variability and are dosed once daily. Dolutegravir drug interactions are similar to raltegravir, whereas boosted elvitegravir participates in additional CYP3A-mediated interactions.

SUMMARY

Raltegravir's potent antiretroviral activity has resulted in widespread use in both treatment-naïve and experienced patients. Dolutegravir and cobicistat-boosted elvitegravir have some pharmacokinetic advantages. Pharmacokinetic data in special populations (pregnancy, pediatrics) to optimize dosing are still required.

Population pharmacokinetic analysis and pharmacogenetics of raltegravir in HIV-positive and healthy individuals

The objectives of this study were to characterize raltegravir (RAL) population pharmacokinetics in HIV-positive (HIV(+)) and healthy individuals, identify influential factors, and search for new candidate genes involved in UDP glucuronosyltransferase (UGT)-mediated glucuronidation. The pharmacokinetic analysis was performed with NONMEM. Genetic association analysis was performed with PLINK using the relative bioavailability as the phenotype. Simulations were performed to compare once- and twice-daily regimens. A 2-compartment model with first-order absorption adequately described the data. Atazanavir, gender, and bilirubin levels influenced RAL relative bioavailability, which was 30% lower in HIV(+) than in healthy individuals. UGT1A9*3 was the only genetic variant possibly influencing RAL pharmacokinetics. The majority of RAL pharmacokinetic variability remains unexplained by genetic and nongenetic factors. Owing to the very large variability, trough drug levels might be very low under the standard dosing regimen, raising the question of a potential relevance of therapeutic drug monitoring of RAL in some situations.