The pharmacokinetics of nevirapine when given with isoniazid in South African HIV-infected individuals

Pharmacokinetics, Safety, and Tolerability of Once-Daily Darunavir With Cobicistat and Weekly Isoniazid/Rifapentine

BACKGROUND

Once-weekly isoniazid with rifapentine (HP) for 3 months is a recommended treatment for latent tuberculosis infection in persons with HIV. HP reduces exposures of certain antiretroviral medications, resulting in limited options for the concomitant use of these therapies. Here, we examined the pharmacokinetics (PK), safety, and tolerability of darunavir/cobicistat with HP.

METHODS

This was an open-label, fixed sequence, two-period crossover study in persons without HIV. Participants received darunavir 800 mg/cobicistat 150 mg once-daily alone for 4 days, then continued darunavir/cobicistat once-daily for days 5-19 with HP coadministration on days 5, 12, and 19. Intensive PK assessments were performed on days 4, 14, and 19. PK parameters were determined using noncompartmental methods. Geometric mean ratios with 90% confidence intervals (CIs) were calculated and compared between phases using mixed-effects models.

RESULTS

Thirteen participants were enrolled. Two withdrew after day 4, and one withdrew after day 14. Of the 3 withdrawals, 2 were attributed to drug-related adverse events. Darunavir area under the concentration-time curve, maximum concentrations (Cmax), and concentrations at 24 hours postdose (C24h) were reduced by 71%, 41%, and 96% ∼48-72 hours after HP administration (day 14), respectively, and 36%, 17%, and 89% with simultaneous HP administration (day 19), respectively. On day 14, 45% of the predose and 73% of C24h concentrations were below the darunavir EC50 (0.055 µg/mL).

CONCLUSIONS

Darunavir exposures were significantly decreased with HP coadministration. Temporal relationships between HP coadministration and the extent of induction or mixed inhibition/induction of darunavir metabolism were apparent. Coadministration of darunavir/cobicistat with 3HP should be avoided.

Pharmacogenetic interactions of rifapentine plus isoniazid with efavirenz or nevirapine

OBJECTIVES

The effect of rifapentine plus isoniazid on efavirenz pharmacokinetics was characterized in AIDS Clinical Trials Group protocol A5279 (NCT01404312). The present analyses characterize pharmacogenetic interactions between these drugs, and with nevirapine.

METHODS

A subset of HIV-positive individuals receiving efavirenz- or nevirapine-containing antiretroviral therapy in A5279 underwent pharmacokinetic evaluations at baseline, and again weeks 2 and 4 after initiating daily rifapentine plus isoniazid. Associations with polymorphisms relevant to efavirenz, nevirapine, isoniazid, and rifapentine pharmacokinetics were assessed.

RESULTS

Of 128 participants, 101 were evaluable for associations with rifapentine and its active 25-desacetyl metabolite, 87 with efavirenz, and 38 with nevirapine. In multivariable analyses, NAT2 slow acetylators had greater week 4 plasma concentrations of rifapentine (P = 2.6 × 10) and 25-desacetyl rifapentine (P = 7.0 × 10) among all participants, and in efavirenz and nevirapine subgroups. NAT2 slow acetylators also had greater plasma efavirenz and nevirapine concentration increases from baseline to week 4, and greater decreases from baseline in clearance. CYP2B6 poor metabolizers had greater efavirenz concentrations at all weeks and greater nevirapine concentrations at baseline. None of 47 additional polymorphisms in 11 genes were significantly associated with pharmacokinetics.

CONCLUSIONS

Among HIV-positive individuals receiving efavirenz or nevirapine, and who then initiated rifapentine plus isoniazid in A5279, NAT2 slow acetylators had greater rifapentine and 25-desacetyl rifapentine concentrations, and greater increases from baseline in plasma efavirenz and nevirapine concentrations. These associations are likely mediated by greater isoniazid exposure in NAT2 slow acetylators.

A Review of Clinical Pharmacokinetic and Pharmacodynamic Profiles of Select Antiretrovirals: Focus on Differences among Chinese Patients

OBJECTIVE

To identify the pharmacokinetic differences of antiretroviral drugs between HIV-infected Chinese patients and patients of other race/ethnicities.

STUDY DESIGN

Results from prospective, open-label pharmacokinetic studies among Chinese and historical data from other race/ethnicities.

PATIENTS

Pharmacokinetics of six commonly used antiretroviral drugs, including zidovudine, lamivudine, tenofovir disoproxil fumarate, nevirapine, efavirenz and lopinavir/ritonavir, was evaluated in HIV-infected Chinese patients and compared with historical data from other race/ethnicities.

ANALYSIS

Pharmacokinetic analyses were performed at the steady state among HIV-infected Chinese patients. Safety data were collected during the follow-up. The pharmacokinetic parameters including maximal concentrations (Cmax), area-under-curve (AUC) and clearance (Cl/F) from the Chinese patients were compared to the historic data from other race/ethnicities.

RESULTS

Current evidence, though limited, suggested that these antiretroviral agents were generally safe and effective among HIV-infected Chinese patients. However, compared with other racial groups, Chinese patients exhibited higher C_max , AUC and lower Cl/F for most of the agents, and the incidences of adverse reactions, for example, liver toxicity, rash, and bone health, were more frequent.

CONCLUSIONS

These pharmacokinetic differences suggest that lower dosages for commonly prescribed antiretroviral drugs in China might be appropriate to reduce drug-related adverse reactions, while maintain the antiviral efficacy.

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.).

Tolerability of Isoniazid Preventive Therapy in an HIV-Infected Cohort of Paediatric and Adolescent Patients on Antiretroviral Therapy from a Resource-Limited Setting: A Retrospective Cohort Study

BACKGROUND

Treating patients with latent tuberculosis infection (LTBI) to prevent development of active disease is an essential strategy for eliminating TB. There are concerns regarding the use of isoniazid due to the potential for hepatotoxicity. This study was conducted to determine the incidence of adverse hepatic events after isoniazid preventive therapy (IPT) commencement in a cohort of HIV-infected paediatric and adolescent patients on antiretroviral therapy (ART).

METHODS

This was a retrospective records review, using data from HIV-infected paediatric and adolescent patients collected during routine clinical visits at Newlands Clinic, Harare, Zimbabwe. Patients included in the analysis had commenced IPT between January 2014 and June 2015 (inclusive) whilst receiving ART. A survival analysis was conducted for the period that participants were receiving IPT with end-points defined by grade 3 or grade 4 elevations in alanine aminotransferase (ALT) levels.

RESULTS

Data from 438 patients commenced on IPT were analysed; 202 (46.1%) of them were female. The median age at IPT commencement was 10 (IQR = 7-12) years. Twenty-eight patients developed grade 3 or 4 elevations in ALT. Concomitant use of nevirapine as part of an ART regimen was the only factor that showed a statistically significant association with ALT elevation [relative risk (RR): 2.7; confidence interval (CI): 1.2-6.3, p = 0.012] compared with those not receiving nevirapine. The incidence of grade 3 or 4 elevations in ALT was 31.5/100 person-years (CI 20.9-45.5).

CONCLUSION

The incidence of IPT-associated ALT elevations was high in this population. We recommend vigilant monitoring of liver enzymes for patients receiving IPT, especially in patients concomitantly receiving nevirapine.

A Comparison of Adverse Drug Reaction Profiles in Patients on Antiretroviral and Antitubercular Treatment in Zimbabwe

INTRODUCTION

Few studies describe the adverse drug event profiles in patients simultaneously receiving antiretroviral and anti-tubercular medicines in resource-limited countries.

OBJECTIVES

To describe and compare the adverse drug reaction profiles in patients on highly active antiretroviral therapy only (HAART), HAART and isoniazid preventive therapy (HHART), and HAART and antitubercular treatment (ATTHAART).

METHODS

We analysed individual case safety reports (ICSRs) for patients on antiretroviral therapy and antitubercular treatment submitted to the national pharmacovigilance centre during the targeted spontaneous reporting (TSR) programme from 1 September 2012 through 31 August 2016. All reports considered certain, probable or possible were included in the analysis.

RESULTS

A total of 1076 ICSRs were included in the analysis. Most of the reports were from the HAART only group (n = 882; 82.0%), followed by patients on HHART (n = 132; 12.3%), and ATTHAART (n = 62; 5.7%). The ATTHAART (35.5%) and HHAART (34.1%) had a higher frequency of hepatic disorders than the HAART group (5.0%) (p < 0.0001). A higher frequency of rash was reported in the HHAART (35.6%) and HAART groups (29.4%) than the ATTHAART group (14.5%) (p = 0.011). Peripheral neuropathy occurred more frequently in the ATTHAART group (19.3%) than other groups (p = 0.001) while Stevens-Johnson syndrome (14.7%; p < 0.001), gynaecomastia (18.2%; p < 0.001), and lipodystrophy (4.5%; p = 0.012) occurred more frequently in the HAART group. The HHAART group was associated with a higher frequency of psychosis (4.5%; p = 0.002).

CONCLUSION

Antiretroviral therapy was associated with a higher frequency of Stevens-Johnson syndrome, gynaecomastia, and lipodystrophy. Co-administration of antiretroviral and antitubercular medicines was associated with a higher frequency of drug-induced liver injury and peripheral neuropathy. Similarly, co-administration of isoniazid preventive therapy and antiretroviral drugs was associated with a higher risk for psychosis. There is a need to carefully manage TB/HIV co-infected patients, due to the higher risk of adverse drug reactions which may lead to poor treatment adherence and outcomes.

Antiretroviral treatment in HIV-infected children who require a rifamycin-containing regimen for tuberculosis

INTRODUCTION

In high prevalence settings, tuberculosis and HIV dual infection and co-treatment is frequent. Rifamycins, especially rifampicin, in combination with isoniazid, ethambutol and pyrazinamide are key components of short-course antituberculosis therapy. Areas covered: We reviewed available data, for which articles were identified by a Pubmed search, on rifamycin-antiretroviral interactions in HIV-infected children. Rifamycins have potent inducing effects on phase I and II drug metabolising enzymes and transporters. Antiretroviral medications are often metabolised by the enzymes induced by rifamycins or may suppress specific enzyme activity leading to drug-drug interactions with rifamycins. These may cause significant alterations in their phamacokinetic and pharmacodynamic properties, and sometimes that of the rifamycin. Recommended strategies to adapt to these interactions include avoidance and dose adjustment. Expert opinion: Despite the importance and frequency of tuberculosis as an opportunistic disease in HIV-infected children, current data on the management of co-treated children is based on few studies. We need new strategies to rapidly assess the use of rifamycins, new anti-tuberculosis drugs and antiretroviral drugs together as information on safety and dosing of individual drugs becomes available.

The pharmacokinetics of lopinavir/ritonavir when given with isoniazid in South African HIV-infected individuals

Isoniazid preventive therapy is recommended in patients on antiretroviral treatment (ART) with latent tuberculous infection to prevent progression to active tuberculosis disease. Isoniazid (INH) inhibits cytochrome (CY) P3A4, which metabolises lopinavir (LPV). The administration of INH may cause higher LPV concentrations, which may increase LPV toxicity. LPV bioavailability is increased by co-formulated ritonavir (r), which may enhance the interaction of INH on LPV. We studied the effect of INH on LPV concentrations by administering INH for 7 days and performing intensive pharmacokinetic sampling in 16 human immunodeficiency virus infected patients established on LPV/r-based ART. INH did not significantly increase steady-state LPV area under the plasma concentration-time curve calculated for the 12 h-dosing interval.

Lipid-based nutrient supplements do not affect efavirenz but lower plasma nevirapine concentrations in Ethiopian adult HIV patients

OBJECTIVES

Lipid-based nutrient supplements (LNSs) are increasingly used in HIV programmes in resource-limited settings. However, the possible effects of LNSs on the plasma concentrations of antiretroviral drugs have not been assessed. Here, we aimed to assess the effects of LNSs on plasma efavirenz and nevirapine trough concentrations in Ethiopian adult HIV-infected patients.

METHODS

The effects of LNSs were studied in adults initiating antiretroviral therapy (ART) in a randomized trial. Patients with body mass index (BMI) > 17 kg/m(2) (n = 282) received daily supplementation of an LNS containing whey (LNS/w), an LNS containing soy (LNS/s) or no LNS. Trough plasma concentrations of efavirenz and nevirapine were measured at 1 and 2 months. Genotyping for 516 G>T and 983 T>C polymorphisms of the cytochrome P450 (CYP) 2B6 locus was performed. Multilevel linear mixed-effects models were used to assess the associations between LNS and plasma efavirenz and nevirapine concentrations.

RESULTS

In patients with BMI > 17 kg/m(2), nevirapine concentrations were lower in the LNS/w and LNS/s groups by a median of -2.3 μg/mL [interquartile range (IQR) -3.9; -0.9 μg/mL; P = 0.002] and -2.1 μg/mL (IQR -3.9; -0.9 μg/mL; P = 0.01), respectively, compared with the group not receiving supplements. There were no differences between groups with respect to efavirenz plasma concentrations. The CYP2B6 516 G>T polymorphism was associated with a 5 μg/mL higher plasma efavirenz concentration compared with the wild type (P < 0.0001), while it was not associated with plasma nevirapine concentrations.

CONCLUSIONS

Intake of an LNS was associated with lower plasma nevirapine trough concentrations, indicating possible drug-LNS interactions. The clinical relevance of such reductions in nevirapine exposure is not clear. Plasma efavirenz concentration was not affected by the LNS.

Pharmacokinetics of isoniazid in low-birth-weight and premature infants

Isoniazid (INH) is recommended for use as posttuberculosis exposure preventive therapy in children. However, no pharmacokinetic data are available for INH treatment in low-birth-weight (LBW) infants, who undergo substantial developmental and physiological changes. Our objectives in this study were to determine the pharmacokinetic parameters of INH at a dose of 10 mg/kg of body weight/day and to define its pharmacokinetics relative to the arylamine N-acetyltransferase-2 (NAT2) genotype. An intensive prospective pharmacokinetic sampling study was conducted at Tygerberg Children's Hospital, South Africa, in which we measured INH blood plasma concentrations at 2, 3, 4 and 5 h postdose. Twenty LBW infants (14 male, 16 exposed to HIV) were studied. The median birth weight was 1,575 g (interquartile range, 1,190 to 2,035 g) and the median gestational age was 35 weeks (interquartile range, 34 to 38 weeks). The NAT2 acetylation statuses of the infants were homozygous slow (SS) (5 infants), heterozygous intermediate (FS) (11 infants), and homozygous fast (FF) (4 infants). Using a noncompartmental analysis approach, the median maximum drug concentration in blood serum (Cmax) was 5.63 μg/ml, the time after drug administration to reach CmaxTmax) was 2 h, the area under the concentration-time curve from 2 to 5 h (AUC2-5) was 13.56 μg · h/ml, the half-life (t1/2) was 4.69 h, and the elimination constant rate (kel) was 0.15 h(-1). The alanine aminotransferase levels were normal, apart from 2 isolated values at two and three times above the normal levels. Only the three-times-elevated value was repeated at 6 months and normalized. All LBW infants achieved target INH blood plasma concentrations comparable to the adult values. Reduced elimination was observed in smaller and younger infants and in slow acetylators, cautioning against higher doses. The safety data, although limited, were reassuring. More data, however, are required for newborn infants.