Hemodialysis does not significantly affect the pharmacokinetics of nevirapine in HIV-1-infected persons requiring hemodialysis: results from ACTG A5177

PBPK Modeling to Recommend Nevirapine Dosing in HIV and HIV-TB Co-infected Patients: Leveraging Enzyme Auto-Induction, Drug Interactions, and Ethnic Variability

Nevirapine, primarily metabolized by CYP2B6 and CYP3A4, exhibits enzyme auto-induction and significant ethnic variability in its pharmacokinetics (PK). These complexities are further exacerbated in HIV-TB co-infected patients, where nevirapine is often co-administered with rifampicin/isoniazid-based anti-tuberculosis (TB) therapies. Rifampicin, a strong CYP3A4 inducer and moderate CYP2B6 inducer, and isoniazid, a moderate CYP3A4 inhibitor, create intricate drug interactions that challenge optimal nevirapine dosing strategies, leading to clinical uncertainty and debate. We developed a physiologically based pharmacokinetic (PBPK) model for nevirapine that integrates auto-induction, drug interactions, and ethnic variability. The model successfully captured the time-dependent PK of nevirapine across Caucasian, African, and Asian populations, with and without rifampicin/isoniazid co-administration. Simulations revealed that the standard nevirapine regimen (200 mg QD lead-in, 200 mg BID maintenance) was appropriate for Caucasian and African HIV patients but required adjustment to 150 mg QD lead-in and 150 mg BID maintenance for Asians to minimize toxicity. In HIV-TB co-infected patients, nevirapine co-administration with rifampicin/isoniazid was unsuitable for Caucasians due to sub-therapeutic levels. For Africans, an increased regimen (200 mg QD lead-in, 300 mg BID maintenance) was recommended, while drug interactions did not alter the reduced dosing recommendation of nevirapine for Asians. Our findings underscore the necessity of incorporating ethnic variability and drug interaction profiles into nevirapine dosing strategies to optimize therapeutic efficacy and safety in HIV and HIV-TB co-infected patients.

Antiretrovirals for People with HIV on Dialysis

In the era of widespread use of antiretroviral therapy (ART), people with HIV (PWH) have a near-normal life expectancy. However, PWH have high rates of kidney diseases and progression to end-stage renal disease at a younger age. PWH have multiple risks for developing acute and chronic kidney diseases, including traditional risk factors such as diabetes, hypertension, and HIV-related factors such as HIV-associated nephropathy and increased susceptibility to infections and exposure to nephrotoxic medications. Despite an improvement in access to kidney transplant among PWH, the number of PWH on dialysis continues to increase. The expansion of the number of antiretrovirals (ARVs) and kidney replacement modalities, the absence of pharmacokinetic data, and therapeutic drug monitoring make it very challenging for providers to dose ARVs appropriately leading to medication errors, adverse events, and higher mortality. Most of the recommendations are either based on small sample size studies or extrapolated based on physiochemical characteristics of ART. We aim to review the most available and most current literature on ART in PWH with renal insufficiency and ART dosing recommendations on dialysis to ensure that PWH are provided with the safest and most effective ART regimen.

Pharmacotherapeutic options for kidney disease in HIV positive patients

INTRODUCTION

Since the developmentof combined antiretroviral therapy (cART), HIV-associated mortality and the incidence of HIV-associated end-stage kidney disease (ESKD) has decreased. However, in the United States, an increase in non-HIV-associated kidney diseases within the HIV-positive population is expected.

AREAS COVERED

In this review, the authors highlight the risk factors for kidney disease within an HIV-positive population and provide the current recommendations for risk stratification and for the monitoring of its progression to chronic kidney disease (CKD), as well as, treatment. The article is based on literature searches using PubMed, Medline and SCOPUS.

EXPERT OPINION

The authors recommend clinicians (1) be aware of early cART initiation to prevent and treat HIV-associated kidney diseases, (2) be aware of cART side effects and discriminate those that may become more nephrotoxic than others and require dose-adjustment in the setting of eGFR ≤ 30ml/min/1.73m², (3) follow KDIGO guidelines regarding screening and monitoring for CKD with a multidisciplinary team of health professionals, (4) manage other co-infections and comorbidities, (5) consider changing cART if drug induced toxicity is established with apparent eGFR decline of ≥ 10ml/min/1.73m² or rising creatinine (≥0.5mg/dl) during drug-drug interactions, and (6) strongly consider kidney transplant in appropriately selected individuals with end stage kidney failure.

Novel Antiretroviral Drugs in Patients with Renal Impairment: Clinical and Pharmacokinetic Considerations

Highly active antiretroviral therapy (HAART) has dramatically increased the survival of HIV-infected patients from Western countries reducing the incidence of opportunistic infections and AIDS-related malignancies, and improving the patients' quality of life compared with the pre-HAART era. HIV is thus now considered in the West as a chronic disease, with the majority of HIV-infected patients successfully reaching an optimal immune and virological outcome a few months after starting HAART. However, this switch from acute to chronic disease has been accompanied by an increased incidence of chronic kidney disease (CKD), reported in up to 60% of HIV-infected patients. Tenofovir disoproxil fumarate (TDF) is considered to play a significant role in the development of CKD in these patients. It has been proposed that tenofovir alafenamide (TAF), a prodrug formulation able to providing lower systemic and renal drug exposure, could potentially contribute to reduce the development of CKD in HAART-treated patients. On the other hand, the pharmacokinetics of some components of HAART can be significantly altered in HIV-infected patients developing CKD. TDF- or TAF-based antiretroviral regimens should be avoided in patients with a creatinine clearance of less than 50 or 30 mL/min, respectively. This review focuses on the pharmacokinetic changes of novel antiretroviral drugs in HIV-infected patients with renal impairment or requiring renal replacement therapy, and provides some suggestions on how to change drug doses in these clinical settings.

A Physiologically-Based Pharmacokinetic Model to Predict Human Fetal Exposure for a Drug Metabolized by Several CYP450 Pathways

BACKGROUND

Pregnant women and their fetuses are exposed to numerous drugs; however, they are orphan populations with respect to the safety and efficacy of drugs. Therefore, the prediction of maternal and fetal drug exposure prior to administration would be highly useful.

METHODS

A physiologically-based pharmacokinetic (PBPK) model for nevirapine, which is metabolized by the cytochrome P450 (CYP) 3A4, 2B6 and 2D6 pathways, was developed to predict maternal and fetal pharmacokinetics (PK). The model was developed in both non-pregnant and pregnant women, and all physiological and enzymatic changes that could impact nevirapine PK were taken into account. Transplacental parameters estimated from ex vivo human placenta perfusion experiments were included in this PBPK model. To validate the model, observed maternal and cord blood concentrations were compared with predicted concentrations, and the impact of fetal clearance on fetal PK was investigated.

RESULTS

By implementing physiological changes, including CYP3A4, 2D6 and 2B6 inductions, we predicted a clearance increase of 21 % in late pregnancy. The PBPK model successfully predicted the disposition for both non-pregnant and pregnant populations. Parameters obtained from the ex vivo experiments allowed the prediction of nevirapine concentrations that matched observed cord blood concentrations. The fetal-to-maternal area under the curve ratio (0-24 h interval) was 0.77, and fetal metabolism had no significant effect on fetal PK.

CONCLUSIONS

The PBPK approach is a useful tool for quantifying a priori the drug exposure of metabolized drugs during pregnancy, and can be applied to evaluate alternative dosing regimens to optimize drug therapy. This approach, including ex vivo human placental perfusion parameters, is a promising approach for predicting human fetal exposure.