Reversible Reduction of Nevirapine Plasma Concentrations During Rifampicin Treatment in Patients Coinfected With HIV-1 and Tuberculosis

Effect of First-Line Antituberculosis Therapy on Nevirapine Pharmacokinetics in Children Younger than Three Years Old

Nevirapine-based antiretroviral therapy (ART) is one of the limited options in HIV-infected children younger than 3 years old (young children) with tuberculosis (TB) coinfection. To date, there are insufficient data to recommend nevirapine-based therapy during first-line antituberculosis (anti-TB) therapy in young children. We compared nevirapine pharmacokinetics (PK) in HIV-infected young children with and without TB coinfection. In the coinfected group, nevirapine PK was evaluated while on anti-TB therapy and after completing an anti-TB therapy regimen. Of 53 participants, 23 (43%) had TB-HIV coinfection. While the mean difference in nevirapine PK parameters between the two groups was not significant (P > 0.05), 14/23 (61%) of the children with TB-HIV coinfection and 9/30 (30%) with HIV infection had a nevirapine minimum concentration (Cmin) below the proposed target of 3.0 mg/liter (P = 0.03). In multivariate analysis, anti-TB therapy and the CYP2B6 516G>T genotype were joint predictors of nevirapine PK parameters. Differences in nevirapine PK parameters between the two groups were significant in children with CYP2B6 516GG but not the GT or TT genotype. Among 14 TB-HIV-coinfected participants with paired data, the geometric mean Cmin and area under the drug concentration-time curve from time zero to 12 h (AUC0-12) were about 34% lower when patients were taking anti-TB therapy, while the nevirapine apparent oral clearance (CL/F) was about 45% higher. While the induction effect of anti-TB therapy on nevirapine PK in our study was modest, the CYP2B6 genotype-dependent variability in the TB drug regimen effect would complicate any dose adjustment strategy in young children with TB-HIV coinfection. Alternate ART regimens that are more compatible with TB treatment in this age group are needed. (This study has been registered at ClinicalTrials.gov under identifier NCT01699633.).

Prevalence and Associations of Psychological Distress, HIV Infection and HIV Care Service Utilization in East Zimbabwe

The correlation between mental health and sexual risk behaviours for HIV infection remains largely unknown in low and middle income settings. The present study determined the prevalence of psychological distress (PD) in a sub-Saharan African population with a generalized HIV epidemic, and investigated associations with HIV acquisition risk and uptake of HIV services using data from a cross-sectional survey of 13,252 adults. PD was measured using the Shona Symptom Questionnaire. Logistic regression was used to measure associations between PD and hypothesized covariates. The prevalence of PD was 4.5% (95% CI 3.9-5.1%) among men, and 12.9% (95% CI 12.2-13.6%) among women. PD was associated with sexual risk behaviours for HIV infection and HIV-infected individuals were more likely to suffer from PD. Amongst those initiated on anti-retroviral therapy, individuals with PD were less likely to adhere to treatment (91 vs. 96%; age- and site-type-adjusted odds ratio = 0.38; 95% CI 0.15, 0.99). Integrated HIV and mental health services may enhance HIV care and treatment outcomes in high HIV-prevalence populations in sub-Saharan Africa.

Pharmacological interactions between rifampicin and antiretroviral drugs: challenges and research priorities for resource-limited settings

Coadministration of antituberculosis and antiretroviral therapy is often inevitable in high-burden countries where tuberculosis (TB) is the most common opportunistic infection associated with HIV/AIDS. Concurrent use of rifampicin and many antiretroviral drugs is complicated by pharmacokinetic drug-drug interactions. Rifampicin is a very potent enzyme inducer, which can result in subtherapeutic antiretroviral drug concentrations. In addition, TB drugs and antiretroviral drugs have additive (pharmacodynamic) interactions as reflected in overlapping adverse effect profiles. This review provides an overview of the pharmacological interactions between rifampicin-based TB treatment and antiretroviral drugs in adults living in resource-limited settings. Major progress has been made to evaluate the interactions between TB drugs and antiretroviral therapy; however, burning questions remain concerning nevirapine and efavirenz effectiveness during rifampicin-based TB treatment, treatment options for TB-HIV-coinfected patients with nonnucleoside reverse transcriptase inhibitor resistance or intolerance, and exact treatment or dosing schedules for vulnerable patients including children and pregnant women. The current research priorities can be addressed by maximizing the use of already existing data, creating new data by conducting clinical trials and prospective observational studies and to engage a lobby to make currently unavailable drugs available to those most in need.

Treatment optimization in patients co-infected with HIV and Mycobacterium tuberculosis infections: focus on drug-drug interactions with rifamycins

Tuberculosis (TB) and HIV continue to be two of the major causes of morbidity and mortality in the world, and together are responsible for the death of millions of people every year. There is overwhelming evidence to recommend that patients with TB and HIV co-infection should receive concomitant therapy of both conditions regardless of the CD4 cell count level. The principles for treatment of active TB disease in HIV-infected patients are the same as in HIV-uninfected patients. However, concomitant treatment of both conditions is complex, mainly due to significant drug-drug interactions between TB and HIV drugs. Rifamycins are potent inducers of the cytochrome P450 (CYP) pathway, leading to reduced (frequently sub-therapeutic) plasma concentrations of some classes of antiretrovirals. Rifampicin is also an inducer of the uridine diphosphate glucuronosyltransferase (UGT) 1A1 enzymes and interferes with drugs, such as integrase inhibitors, that are metabolized by this metabolic pathway. Rifampicin is also an inducer of the adenosine triphosphate (ATP) binding cassette transporter P-glycoprotein, which may also lead to decreased bioavailability of concomitantly administered antiretrovirals. On the other side, rifabutin concentrations are affected by the antiretrovirals that induce or inhibit CYP enzymes. In this review, the pharmacokinetic interactions, and the relevant clinical consequences, of the rifamycins-rifampicin, rifabutin, and rifapentine-with antiretroviral drugs are reviewed and discussed. A rifampicin-based antitubercular regimen and an efavirenz-based antiretroviral regimen is the first choice for treatment of TB/HIV co-infected patients. Rifabutin is the preferred rifamycin to use in HIV-infected patients on a protease inhibitor-based regimen; however, the dose of rifabutin needs to be reduced to 150 mg daily. More information is required to select optimal treatment regimens for TB/HIV co-infected patients whenever efavirenz cannot be used and rifabutin is not available. Despite significant pharmacokinetic interactions between antiretrovirals and antitubercular drugs, adequate clinical response of both infections can be achieved with an acceptable safety profile when the pharmacological characteristics of drugs are known, and appropriate combination regimens, dosing, and timing of initiation are used. However, more clinical research is needed for newer drugs, such as rifapentine and the recently introduced integrase inhibitor antiretrovirals, and for specific population groups, such as children, pregnant women, and patients affected by multidrug-resistant TB.

Nevirapine or efavirenz for tuberculosis and HIV coinfected patients: exposure and virological failure relationship

Objectives

We describe nevirapine and efavirenz exposure on and off tuberculosis treatment and consequences for virological efficacy and tolerance in patients included in the ANRS 12146/12214-CARINEMO trial.

Methods

Participants were randomly selected to receive either nevirapine at 200 mg twice daily (n = 256) or efavirenz at 600 mg daily (n = 270), both combined with two nucleoside analogues. Blood samples were drawn 12 h after nevirapine or efavirenz administration, while on tuberculosis treatment and after tuberculosis treatment discontinuation. In 62 participants, samples taken 12 h after drug administration were drawn weekly for the first month of ART. Sixteen participants participated in an extensive pharmacokinetic study of nevirapine. Concentrations were compared with the therapeutic ranges of 3000–8000 ng/mL for nevirapine and 1000–4000 ng/mL for efavirenz.

Results

Nevirapine concentrations at the end of the first week of treatment (on antituberculosis drugs) did not differ from concentrations off tuberculosis treatment, but declined thereafter. Concentrations at steady-state were 4111 ng/mL at week 12 versus 6095 ng/mL at week 48 (P < 0.0001). Nevirapine concentrations <3000 ng/mL were found to be a risk factor for virological failure. Efavirenz concentrations were higher on than off tuberculosis treatment (2700 versus 2450 ng/mL, P < 0.0001).

Conclusions

The omission of the 2 week lead-in dose of nevirapine prevented low concentrations at treatment initiation but did not prevent the risk of virological failure. Results support the WHO recommendation to use efavirenz at 600 mg daily in patients on rifampicin-based antituberculosis therapy.

Nevirapine versus efavirenz for patients co-infected with HIV and tuberculosis: a randomised non-inferiority trial

BACKGROUND

In countries with a high incidence of HIV and tuberculosis co-infection, nevirapine and efavirenz are widely used as antiretroviral therapy but both interact with antituberculosis drugs. We aimed to compare efficacy and safety of a nevirapine-based antiretroviral therapy (started at full dose) with an efavirenz-based regimen in co-infected patients.

METHODS

We did a multicentre, open-label, randomised, non-inferiority trial at three health centres in Maputo, Mozambique. We enrolled adults (≥18 years) with tuberculosis and previously untreated HIV infection (CD4 cell counts <250 cells per μL) and alanine aminotransferase and total bilirubin concentrations of less than five times the upper limit of normal. 4-6 weeks after the start of tuberculosis treatment, we randomly allocated patients (1:1) with central randomisation, block sizes of two to six, and stratified by site and CD4 cell count to nevirapine (200 mg twice daily) or efavirenz (600 mg once daily), plus lamivudine and stavudine. The primary endpoint was virological suppression at 48 weeks (HIV-1 RNA <50 copies per mL) in all patients who received at least one dose of study drug (intention-to-treat population); death and loss to follow-up were recorded as treatment failure. The non-inferiority margin for the difference of efficacy was 10%. We assessed efficacy in intention-to-treat and per-protocol populations and safety in all patients who received study drug. This study is registered with ClinicalTrials.gov, number NCT00495326.

FINDINGS

Between October, 2007, and March, 2010, we enrolled 285 patients into each group. 242 (85%) patients in the nevirapine group and 233 (82%) patients in the efavirenz group completed follow-up. In the intention-to-treat population, 184 patients (64·6%, 95% CI 58·7-70·1) allocated nevirapine achieved virological suppression at week 48, as did 199 patients (69·8%, 64·1-75·1) allocated efavirenz (one-sided 95% CI of the difference of efficacy 11·7%). In the per-protocol population, 170 (70·0%, 63·8-75·7) of 243 patients allocated nevirapine achieved virological suppression at week 48, as did 194 (78·9%, 73·2-83·8) of 246 patients allocated efavirenz (one-sided 95% CI 15·4%). The median CD4 cell count at randomisation was 89 cells per μL. 15 patients substituted nevirapine with efavirenz and six patients substituted efavirenz with nevirapine. 20 patients allocated nevirapine (7%) had grade 3-4 increase of alanine aminotransferase compared with 17 patients allocated efavirenz (6%). Three patients had severe rash after receipt of nevirapine (1%) but no patients did after receipt of efavirenz. 18 patients in the nevirapine group died, as did 17 patients in the efavirenz group.

INTERPRETATION

Although non-inferiority of the nevirapine-regimen was not shown, nevirapine at full dose could be a safe, acceptable alternative for patients unable to tolerate efavirenz.

FUNDING

French Research Agency for HIV/AIDS and hepatitis (ANRS).

Pharmacokinetics of nevirapine in HIV and tuberculosis-coinfected children receiving antiretroviral fixed-dose combination tablets while receiving rifampicin-containing tuberculosis treatment and after rifampicin discontinuation

We assessed the pharmacokinetics of nevirapine in HIV and tuberculosis-coinfected children while they were receiving nevirapine-containing fixed-dose combination tablets with rifampicin-based tuberculosis treatment and after discontinuation. The median age (range) was 9.7 (4.4-11.7) years. The nevirapine area under the concentration versus time curve from 0 to 12 hours and trough concentration with rifampicin were 85.3 (40.5-170.7) mg.h/mL and 6.4 (3.00-13.27) mg/mL, respectively, providing adequate exposure.

Systemic exposure to rifampicin in patients with tuberculosis and advanced HIV disease during highly active antiretroviral therapy in Burkina Faso

OBJECTIVES

Low plasma concentrations of rifampicin, an essential antituberculosis drug, have been reported particularly among HIV co-infected persons. In a prospective, longitudinal study we measured rifampicin systemic exposure at different timepoints during highly active antiretroviral therapy (HAART).

PATIENTS AND METHODS

From May 2006 to April 2007, 16 tuberculosis (TB)/HIV co-infected patients were enrolled in Ouagadougou, Burkina Faso. All patients received fixed dose combinations of rifampicin, isoniazid, pyrazinamide and ethambutol under direct observation and HAART, consisting of a fixed dose combination of stavudine, lamivudine and nevirapine. Rifampicin concentrations during the dosing interval were determined by HPLC at three different timepoints: (i) after 2 weeks of TB therapy and before starting HIV therapy (T0); (ii) after 4 weeks of combined therapy (T1); and (iii) after 10 weeks of combined therapy (T2).

RESULTS

The median values of the area under the curve (AUC(0-24)) of rifampicin increased by 39% at T1 (15.69 μg · h/mL; P = 0.01) and by 83% at T2 (20.65 μg · h/mL; P = 0.001) compared with T0 (11.28 μg · h/mL). Similar variations were observed for the median C(max) at T0 (2.24 μg/mL) compared with T2 (2.83 μg/mL; P = 0.003). However, none of the subjects had C(max) levels >8 μg/mL at either T0 or T2.

CONCLUSIONS

Rifampicin systemic exposure increased during combined TB and HIV therapy, possibly due to increased drug absorption or decreased oral clearance, but remained invariably low in this population. Studies to define the C(max) rifampicin concentrations, which are associated with a significantly increased risk of treatment failure, are urgently warranted.