Assessing the Impact of Substance use and Hepatitis Coinfection on Atazanavir and Lopinavir Trough Concentrations in HIV-Infected Patients During Therapeutic Drug Monitoring

Lipid-Lowering Therapy in HIV-Infected Patients: Relationship with Antiretroviral Agents and Impact of Substance-Related Disorders

BACKGROUND

The use of combination antiretroviral therapy (cART) has significantly decreased the morbidity and mortality associated with human immunodeficiency virus (HIV) infection. Lipid disorders, including lipodystrophy, hypertriglyceridemia, and hypercholesterolemia, remain the most commonly reported metabolic disorders among those treated with long-term cART. Mounting evidence suggests an association between drug abuse and poor glycemic control and diabetes complications. Substance related disorders (SRD) may increase the risk of metabolic syndrome.

MATERIALS AND METHODS

The aim of this retrospective cohort study was to examine the relationship between SRD, cART, and lipid-lowering agent use in an HIV infected population. Patients received efavirenz or protease inhibitor-based cART for at least 6 months. Prescription information was retrieved from the medical records. The primary outcome was the use of lipid-lowering agents including statins, fibrates and fish oil. The impact of SRD and cART was assessed on the lipid-lowering agent use.

RESULTS

A total of 276 subjects with HIV infection were included, 90 (33%) received lipid-lowering agents, and 31 (34%) had SRD. Smoking was prevalent among subjects with SRD (84 vs 15%, p<0.001). Statins were the mainstay for the management of dyslipidemia (66%), followed by the fibrates (24%), omega-3 fatty acids (5%), nicotinic acid (3%) and the cholesterol absorption inhibitors (3%). Use of statins or fibrates was significantly higher among subjects without SRD than those with (40 vs 23%, p=0.005). The type of cART, including efavirenz and protease inhibitors, appeared to have no significant impact on the use pattern of lipid-lowering agents. Lopinavir/ritonavir (lopinavir/r) was mostly prescribed for subjects with SRD (25 vs 8%, p=0.02).

CONCLUSION

Among HIV-infected patients, statins remain the mainstay for the management of dyslipidemia in routine clinical care, followed by fibrates. A significant high risk of metabolic disorders among patients with SRD is implicated by heavy tobacco use and prevalent lopinavir/r-based treatment. Significantly low rate of lipid-lowering agent use in this population underscores the importance of lipid disorder scrutiny and cART treatment optimization for HIV-infected patients with SRD.

Therapeutic drug monitoring of protease inhibitors and efavirenz in HIV-infected individuals with active substance-related disorders

BACKGROUND

Achieving targeted antiretroviral (ARV) plasma concentrations during long-term treatment in human immunodeficiency virus (HIV)-infected patients with substance-related disorders (SRDs) may be challenging due to a number of factors, including medication adherence, coinfection with hepatitis B or C virus, medication intolerance, and drug interactions. One approach to investigate these factors is to conduct therapeutic drug monitoring to measure ARV exposure during treatment. The objective of this study was to utilize therapeutic drug monitoring to compare efavirenz (EFV) and protease inhibitor pharmacokinetics in patients with and without SRDs.

METHODS

This was a multicenter, cross-sectional open-label study in patients with HIV-1 infection receiving antiretroviral therapy (ART), with active (n=129) or without (n=146) SRD according to National Institute on Drug Abuse criteria. Two hundred seventy-five subjects who were receiving either protease inhibitor-based or EFV-based ART regimens for >6 months were enrolled at 4 HIV treatment centers with an equal distribution of SRD and non-SRD at each site. The patients were instructed during enrollment visits with regard to the importance of adherence before and after study visits. Demographics and routine clinical laboratory tests were recorded.

RESULTS

Among the 275 patients, 47% had SRD with at least 1 substance. There were no significant differences between SRD and non-SRD groups for race, gender, age, or CD4 count at entry. A significantly higher proportion of patients with SRD had an entry HIV RNA plasma concentration>75 copies per milliliter compared with patients without SRD (40% vs 28%, P=0.044). Logistic regression modeling revealed an association between HIV RNA plasma concentration and African American race (P=0.017). A significantly higher proportion of SRDs also had an EFV or protease inhibitor trough concentration below the desired range (23% vs 9%, P=0.048). Significantly lower trough concentrations were noted in patients with SRDs receiving atazanavir (0.290 vs 0.976 μg/mL) or lopinavir (3.75 vs 5.30 μg/mL).

CONCLUSIONS

The pharmacokinetic data indicate differences between HIV-infected patients with and without SRDs that may influence viral load suppression during long-term ART. These findings require additional investigation in a randomized design with more intensive pharmacokinetic assessment to identify individual factors that are contributing to suboptimal ARV exposure in patients with SRDs.

Non-injection drug use and HIV disease progression in the era of combination antiretroviral therapy

Little is known about the effects of non-injection drug use (NIDU) on HIV antiretroviral treatment outcomes. We conducted a systematic literature search and identified nine publications from prospective cohort studies investigating the relationship between NIDU and clinical HIV disease progression. Hazard ratios from studies estimating the effect of drug use on time to AIDS-related mortality ranged from 0.89 to 3.61, and only two of these were statistically significant. Hazard ratios from studies assessing time to an AIDS-defining event ranged from 1.19 to 2.51, with 8 of the 14 estimates falling between 1.55 and 1.65 regardless of drug use definition and measurement of use or frequency. It is suggested that NIDU may have a moderate effect of increasing the risk of progression to AIDS, but its impact on AIDS-related mortality is uncertain. NIDU may affect HIV antiretroviral treatment outcomes primarily through interaction with antiretroviral therapy and, to a lesser extent, through immune modulation and deterioration of general health. The limitations about published studies are discussed, and future perspectives on research on this topic are provided.

Within-Patient Atazanavir Trough Concentration Monitoring in HIV-1-Infected Patients

Objective: Protease inhibitors (PIs) exhibit considerable interpatient pharmacokinetic variability in plasma trough concentrations. Therapeutic drug monitoring (TDM) is occasionally used to guide chronic dosing to achieve target trough concentrations, but its clinical success assumes minimal intrasubject variability. Therefore, our primary objective was to evaluate intrapatient variability in atazanavir (ATV) plasma trough concentrations in HIV-1-infected patients. Design/Methods: In a single-site, prospective, cohort study, patients on atazanavir with or without ritonavir (ATV/r or ATV) for 2 clinic visits were enrolled. Adherence and time since last dose (TSLD) were verified at each visit. ATV was assayed with high-performance liquid chromatography. Intra- and interpatient variation was evaluated using the median intraindividual percentage coefficient of variation (ICV). Results: The mean 24-hour ATV trough concentrations for the first and second visit for the ATV/r group (n = 10) was 598 (CV 84%) and 525 ng/mL (CV 66%), respectively ( P = .511), and 300 (CV 81%) and 434 ng/mL (CV 106%) for the ATV group (n = 4), respectively ( P = .369). Median ICV was 43.1% for all patients (range: 0.6%-107.6%), 38.1% (0.6%-107.6%) for the ATV/r group, and 33.1% (2.3%-87.6%) for the ATV group. Conclusions: Potential intrapatient variability in ATV troughs suggests that repeated measurements may be required to ensure that target values are maintained.

Assessing the impact of hepatitis C virus coinfection on lopinavir/ritonavir trough concentrations in HIV-infected patients

PURPOSE

Chronic hepatitis C is an emerging issue in the management of human immunodeficiency virus (HIV) disease because both diseases have the same route of transmission, leading to a very high prevalence of hepatitis C virus (HCV)-coinfection in the HIV-positive patient population. Lopinavir is extensively metabolized by the hepatic cytochrome P450 3A4, and the pharmacokinetics of this protease inhibitor (PI) could be influenced by liver impairment. However, data currently available on the impact of HCV-coinfection on lopinavir plasma concentrations are both limited and conflicting.

METHODS

This was an observational, open-label study in which adult HIV-infected outpatients on stable antiretroviral treatment that included two nucleoside reverse transcriptase inhibitors (NRTIs) plus lopinavir/ritonavir for at least 4 weeks were asked to participate. The trough plasma concentration (C (trough)) of lopinavir and ritonavir was assessed at steady state by a validated high-performance liquid chromatography-tandem mass spectrometry method.

RESULTS

A total of 65 HIV-positive patients were enrolled in the study. These patients were stratified into two groups based on the absence/presence of HCV-coinfection: 45 were monoinfected (HIV+/HCV-) and 20 were coinfected (HIV+/HCV+). The lopinavir C (trough) in plasma was comparable between HIV+/HCV+ and HIV+/HCV- patients, without any statistically significant difference (geometric mean ratio 0.89, 95% confidence interval 0.61-1.42; p = 0.581). The mean ritonavir C (trough) was also comparable in the two groups. Almost all samples were found to be within the therapeutic plasma level range (97% in HIV+/HCV- group and 100% in HIV+/HCV+ group). No correlation was found between lopinavir plasma levels and adverse events (such as diarrhoea and hypertriglyceridaemia) or immune-virological parameters of HIV disease.

CONCLUSIONS

Among the HIV-positive patients participating in this study, the pharmacokinetics of lopinavir/ritonavir did not significantly change in those HIV-positive patients coinfected with HCV and in the absence of liver cirrhosis.

Atazanavir: its role in HIV treatment

Azatanavir is a protease inhibitor (PI) approved for the treatment of HIV-1 infection. Atazanavir is a substrate and inhibitor of cytochrome P450 isozyme 3A and an inhibitor and inducer of P-glycoprotein. It has similar virologic efficacy as efavirenz and ritonavir-boosted lopinavir in antiretroviral-naive individuals. Its impact on lipids is less than other PIs and it is suitable for those in whom hyperlipidemia is undesirable. Ritonavir boosting of atazanavir enhances the bioavailability of atazanavir but may result in some elevation of lipids and is recommended for treatment-experienced patients and those receiving efavirenz or tenofovir. Ritonavir-boosted atazanavir has similar antiviral activity as ritonavir-boosted lopinavir in both antiretroviral therapy-naive and -experienced patients. Atazanavir causes unconjugated bilirubinemia in over 40% of patients but results in less than 2% discontinuations. Atazanavir is licensed for once-daily use and atazanavir/ritonavir competes with lopinavir/ritonavir as the most commonly prescribed PI.