Management of the Drug-Drug Interactions Between Valproic Acid and Dolutegravir-A Case Study

OBJECTIVE

Preliminary evidence shows that concomitant administration of valproic acid can reduce the exposure to dolutegravir with limited clinical impacts. Here, we describe a male living with HIV who experienced a drastic reduction in dolutegravir trough concentrations a few weeks after starting valproic acid treatment as identified by therapeutic drug monitoring. Concomitantly, pharmacists recommended a supplementation of magnesium to improve insomnia.

CASE REPORT

A 62-year-old man with HIV on antiretroviral therapy with dolutegravir and lamivudine recently added valproic acid to clonazepam and sertraline to treat severe sleep disturbances. An 84% reduction in dolutegravir trough concentrations was observed compared with the previous outpatient visit (418 versus 2714 ng/mL), with values close to the minimum effective drug concentration (300 ng/mL). Considering this, we strongly discourage the use of magnesium.

CONCLUSIONS

We are confident that our findings can contribute to a better understanding of the clinical problems that infectious disease physicians encounter in their daily management of people with HIV and how therapeutic drug monitoring may add value in this context. This case also highlights the importance of multidisciplinary services for the optimal management of polypharmacy in people with HIV.

Clinical Relevance of Drug Interactions in People Living with Human Immunodeficiency Virus on Antiretroviral Therapy-Update 2022: Systematic Review

BACKGROUND

The clinical outcomes of antiretroviral drugs may be modified through drug interactions; thus, it is important to update the drug interactions in people living with HIV (PLHIV).

AIM

To update clinically relevant drug interactions in PLHIV on antiretroviral therapy with novel drug interactions published from 2017 to 2022.

METHODS

A systematic review in Medline/PubMed database from July 2017 to December 2022 using the Mesh terms antiretroviral agents and drug interactions or herb-drug interactions or food-drug interactions. Publications with drug interactions in humans, in English or Spanish, and with full-text access were retrieved. The clinical relevance of drug interactions was grouped into five levels according to the gravity and probability of occurrence.

RESULTS

A total of 366 articles were identified, with 219 (including 87 citation lists) were included, which allowed for the identification of 471 drug interaction pairs; among them, 291 were systematically reported for the first time. In total 42 (14.4%) and 137 (47.1%) were level one and two, respectively, and 233 (80.1%) pairs were explained with the pharmacokinetic mechanism. Among these 291 pairs, protease inhibitors (PIs) and ritonavir/cobicistat-boosted PIs, as well as integrase strand transfer inhibitors (InSTIs), with 70 (24.1%) and 65 (22.3%) drug interaction pairs of levels one and two, respectively, were more frequent.

CONCLUSIONS

In PLHIV on antiretroviral therapy, we identify 291 drug interaction pairs systematically reported for the first time, with 179 (61.5%) being assessed as clinically relevant (levels one and two). The pharmacokinetic mechanism was the most frequently identified. PIs, ritonavir/cobicistat-boosted PIs, and InSTIs were the antiretroviral groups with the highest number of clinically relevant drug interaction pairs (levels one and two).

Pharmacokinetic interactions of modern antiretroviral therapy

Drug--drug interactions (DDIs) have been a clinical challenge in HIV medicine for over two decades. The newer antiretroviral drugs (ARTs) have significantly fewer DDIs than protease inhibitors and boosted integrase inhibitors (INSTIs). The lower propensity of such newer antiretrovirals (e.g. unboosted integrase inhibitors; doravirine) to cause DDIs, has been largely offset by the ageing cohort of patients with multiple comorbidities, who are taking multiple chronic medicines. Furthermore, the introduction of newly marketed drugs into clinical practice needs to be closely monitored, as the new drugs may be perpetrators of DDIs, leading to a potential change in the efficacy or toxicity of the coadministered antiretrovirals.

The dolutegravir/valproic acid drug-drug interaction is primarily based on protein displacement

OBJECTIVES

The dolutegravir/valproic acid drug-drug interaction (DDI) is suggested to be caused by protein displacement. Here, we assess the underlying mechanism.

METHODS

Participants in a randomized controlled trial investigating valproic acid as an HIV latency reversing agent were recruited in a predefined pharmacokinetic substudy if they were on once-daily 50 mg dolutegravir-containing combination ART (cART) for >12 months with a plasma HIV-RNA <50 copies/mL (trial registration: ClinicalTrials.gov NCT03525730). Participants were randomized to receive 30 mg/kg/day valproic acid orally (divided into two equal doses) for 14 days or not. Total and unbound dolutegravir concentrations were measured on day 0 (before intake of valproic acid and 6 h after intake of valproic acid) and on days 1, 7, 14 and 42. Intra- and inter-subject dolutegravir concentrations and geometric means (GMs) were evaluated.

RESULTS

Six of 10 participants on dolutegravir were randomized to receive valproic acid. During 14 days of valproic acid treatment, the GM total dolutegravir concentration decreased sharply from 1.36 mg/L on day 0 to 0.85, 0.31 and 0.20 mg/L on days 0, 1, 7 and 14, respectively, while total dolutegravir concentrations in the controls remained comparable during the same period: 1.27-1.49 mg/L. We observed a parallel increase in unbound dolutegravir fractions ranging from 0.39% to 0.58% during valproic acid administration, compared with 0.25% to 0.28% without valproic acid. Unbound dolutegravir concentrations were above the established in vitro EC90 value for unbound dolutegravir in 85% of the tested samples.

CONCLUSIONS

This study confirms protein displacement as the main mechanism for this DDI, although additional mechanisms might be involved too. If dolutegravir is taken with food, this DDI is probably not clinically relevant.

Antiretroviral concentrations in the presence and absence of valproic acid

OBJECTIVES

An unexpected drug-drug interaction has been recently reported between dolutegravir, an HIV integrase inhibitor, and valproic acid. Despite there being several potential underlying mechanisms, plasma protein displacement has been suggested. The aim of this study was to assess plasma concentrations of several antiretrovirals when administered with or without valproic acid.

METHODS

We performed a therapeutic drug monitoring registry analysis and identified patients concomitantly taking antiretrovirals and valproic acid and without clinical affecting conditions or interacting drugs.

RESULTS

One hundred and thirty-four patients were identified. Median (IQR) age and BMI were 49.7 years (45-56) and 23.4 kg/m2 (20.8-26.3) and 78 were male (58.2%). Despite small groups, we observed no major effect on antiretroviral exposure, even when considering highly protein-bound compounds (such as etravirine), with the exception of dolutegravir trough concentrations [median (IQR) = 132 ng/mL (62-227) in individuals on valproic acid versus 760 ng/mL (333-1407) in those not receiving valproic acid].

CONCLUSIONS

Valproic acid does not have a major effect on antiretrovirals other than dolutegravir. The mechanism of this unexpected drug-drug interaction may be the combination of protein displacement, reduced absorption and CYP3A4 induction.

Dolutegravir-Based Antiretroviral Regimens for HIV Liver Transplant Patients in Real-Life Settings

Background and Objectives

Liver transplantation is now considered a safe procedure in patients with HIV because of the advent of potent antiretroviral therapies (ART).

Objective

We aimed to describe the use of dolutegravir-based maintenance ART in patients with HIV and liver transplant regularly followed in our hospital.

Methods

We searched the database of our Department of Infectious Diseases for liver transplant recipients receiving calcineurin inhibitor-based maintenance immunosuppression concomitantly treated with dolutegravir for at least 1 month.

Results

Ten HIV-positive liver transplant recipients were identified. At 4.6 ± 3.5 years post-transplant, all the patients were switched to dolutegravir-based therapies for treatment simplification. However, at 1 year after the switch, five of the ten patients returned to their previous ART regimens because of increased serum transaminases (n = 1), reversible increased serum creatinine (n = 4), repeated episodes of nausea/vomiting (n = 1) and variable out-of-range concentrations of tacrolimus or cyclosporine (n = 2). However, it should be recognized that these events cannot be unequivocally ascribed to dolutegravir and, in the case of increased serum creatinine, are predictable.

Conclusions

The management of HIV-positive liver transplant recipients in clinical practice is a complex task, where possibility of simplifying antiretroviral regimens must be balanced with the need to guarantee optimal immunosuppression and the finest treatment tolerability. A multidisciplinary approach involving physicians and clinical pharmacologists/pharmacists could help achieve this goal.

Epilepsy management in pregnant HIV+ women in sub-Saharan Africa, clinical aspects to consider: a scoping review

BACKGROUND

Since the introduction of highly active antiretroviral therapy (HAART), acquired immune deficiency syndrome (AIDS) related mortality has markedly declined. As HAART is becoming increasingly available, the infection with human immunodeficiency virus (HIV+) in sub-Saharan Africa (SSA) is becoming a chronic condition. While pregnancy in HIV+ women in SSA has always been considered a challenging event for the mother and the fetus, for pregnant HIV+ women also diagnosed with epilepsy (WWE), there are additional risks as HIV increases the odds of developing seizures due to the vulnerability of the central nervous system to other infections, immune dysfunction, and overall metabolic disturbances. In light of a growing proportion of HIV+ WWE on HAART and an increasing number of pregnant women accessing mother-to-child transmission of HIV programs through provision of HAART in SSA, there is a need to develop contextualized and evidenced-based clinical strategies for the management of epilepsy in this population. In this study, we conduct a literature scoping review to identify issues that warrant consideration for clinical management.

RESULT

Twenty-three articles were retained after screening, which covered six overarching clinical aspects: status epilepticus (SE), Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN), dyslipidemia, congenital malformation (CM), chronic kidney disease (CKD), and neurological development. No studies for our population of interest were identified, highlighting the need for a cautionary approach to be employed when extrapolating findings.

CONCLUSION

High risks of CM and drug interactions with first-line antiepileptic drugs (AEDs) warrant measures to increase the accessibility and choices of safer second-line AEDs. To ensure evidence-based management of epilepsy within this population, the potential high prevalence of SE, CKD, dyslipidemia, and SJS/TEN and the cumulative effect of drug-drug interactions should be considered. Further understanding of the intersections between pregnancy and drug-drug interactions in SSA is needed to ensure evidenced-based management of epilepsy in pregnant HIV+ WWE. To prevent SE, the barriers for AED treatment adherence in pregnant HIV+ women should be explored. Our review underscores the need to conduct cohort studies of HIV+ WWE in reproductive age over time and across pregnancies to capture the cumulative effect of HAART and AED to inform clinical management.

Drug-Drug Interactions with Antiretroviral Drugs in Pregnant Women Living with HIV: Are They Different from Non-Pregnant Individuals?

BACKGROUND AND OBJECTIVE

Although the separate effects of drug-drug interactions and pregnancy on antiretroviral drug pharmacokinetics have been widely studied and described, their combined effect is largely unknown. Physiological changes during pregnancy may change the extent or clinical relevance of a drug-drug interaction in a pregnant woman. This review aims to provide a detailed overview of the mechanisms, magnitude, and clinical significance of antiretroviral drug-drug interactions in pregnant women.

METHODS

We performed a literature search and selected studies that compared the magnitude of drug-drug interactions with antiretroviral drugs in pregnant vs non-pregnant women.

RESULTS

Forty-eight papers examining drug-drug interactions during pregnancy were selected, of which the majority focused on pharmacokinetic boosting. Other selected studies examined the drug-drug interactions between efavirenz and lumefantrine, efavirenz and tuberculosis drugs, etravirine and tenofovir disoproxil fumarate, atazanavir and tenofovir disoproxil, and mefloquine and nevirapine in pregnant compared to non-pregnant women. The clinical significance of antiretroviral drug-drug interactions changed during pregnancy from a minimal effect to a contra-indication. In almost all cases, the clinical significance of a drug-drug interaction was more relevant in pregnant women, owing to the combined effects of pregnancy-induced physiological changes and drug-drug interactions leading to a lower absolute drug exposure.

CONCLUSIONS

Multiple studies show that the clinical relevance of a drug-drug interaction can change during pregnancy. Unfortunately, many potential interactions have not been studied in pregnancy, which may place pregnant women living with human immunodeficiency virus and their newborns at risk.

Assessment of Antiepileptic Drug Concentrations in HIV-Infected versus HIV-Negative Patients: A Retrospective Analysis

INTRODUCTION

A higher rate of subtherapeutic psychotropic drug concentrations was recently found in HIV-infected versus HIV-negative patients. In this study, we sought to investigate if this trend could also apply to antiepileptic drugs.

METHODS

Overall, 700 HIV-infected patients were screened during the first 2 years after the introduction of our outpatient polytherapy management service (Gestione Ambulatoriale Politerapie [GAP]) in the search for subjects with antiepileptic drug trough concentration assessments. The distribution of such concentrations was compared with that in HIV-negative patients monitored over the same period.

RESULTS

The search identified 97 HIV-infected patients concomitantly receiving antiretroviral and antiepileptic drugs, for a total of 310 drug measurements. Overall, 30%, 64% and 6%, versus 28%, 65% and 7%, of the antiepileptic concentrations measured in HIV-infected versus HIV-negative patients (1090 patients, for a total of 3488 antiepileptic concentrations measured) were below, within, or above the therapeutic targets, respectively. The antiepileptic drug valproate was associated with the highest risk of subtherapeutic drug concentrations, with 57% and 46% of determinations below the therapeutic range in HIV-positive and HIV-negative patients, respectively. Remarkably, the concentrations of valproate were significantly lower in HIV-infected versus HIV-negative patients (47.9 ± 21.2 versus 53.9 ± 21.6 mg/L; p < 0.05).

CONCLUSION

In our retrospective study, most HIV-infected patients had antiepileptic drug concentrations falling within the therapeutic targets, with the exception of valproate, which was associated with a higher rate of subtherapeutic concentrations compared with other antiepileptic drugs.

Older Age is Associated with Higher Dolutegravir Exposure in Plasma and Cerebrospinal Fluid of People Living with HIV

BACKGROUND

People living with human immunodeficiency virus are ageing under combination antiretroviral treatments but data on drug exposure in serum and cerebrospinal fluid are limited. Dolutegravir is a widely used second-generation integrase strand transfer inhibitor: conflicting data suggest that neuropsychiatric side effects may present at a higher frequency in patients with higher dolutegravir serum concentrations.

METHODS

We performed a retrospective analysis of our therapeutic drug monitoring registry identifying patients receiving once-daily dolutegravir without concomitant interacting drugs and significant clinical conditions. Data were analysed stratifying time after drug dose intake (maximum concentration 0.5-4 and trough concentration 21-27 h). Cerebrospinal fluid samples from patients enrolled in neurological studies and receiving dolutegravir were analysed for dolutegravir cerebrospinal fluid concentrations and cerebrospinal fluid-to-plasma ratios. Serum and cerebrospinal fluid concentrations were measured through validated chromatographic methods.

RESULTS

We included 207 (providing 457 serum samples) and 41 patients (providing 41 cerebrospinal fluid samples). Participants were mostly male (68.2-72.8%) of median age of 50 years (50-53 years). Non-significant changes in dolutegravir maximum concentration and trough concentration were observed with age at Spearman's test (p values > 0.05); linear logistic regression showed a significant effect of age on dolutegravir trough concentration (p = 0.0013) (Fig. 1). Dolutegravir maximum concentration [3830 ng/mL (2311-5057) vs 4230 ng/mL (2919-5272), p = 0.311] and trough concentration [838 ng/mL (362-1587) vs 966 ng/mL (460-2085), p = 0.056] were non-significantly or borderline higher in patients aged > 50 years. Cerebrospinal dolutegravir concentrations were associated with plasma concentrations (ρ = 0.374, p = 0.016) and age (ρ = 0.537, p = 0.003); cerebrospinal fluid dolutegravir concentrations (13.8 vs 7.3 ng/mL, p = 0.015) and cerebrospinal fluid-to-plasma ratios (0.57 vs 0.32%, p = 0.017] were higher in participants aged > 50 years.

CONCLUSIONS

We observed an increase in dolutegravir exposure in serum and in cerebrospinal fluid in older patients living with human immunodeficiency virus.

Dolutegravir plus lamivudine for the treatment of HIV-1 infection

Introduction: Recent data on the 2-drug regimen (2DR) with dolutegravir (DTG) plus lamivudine (3TC) have shown high efficacy and tolerability both in treatment-naïve and experienced HIV-positive patients. Current guidelines recommend DTG+3TC as an alternative to triple antiretroviral therapy (ART) in selected patients to reduce long-term toxicity and costs.Areas covered: This review is intended to provide insight about the efficacy, safety, and tolerability of a 2DR with DTG+3TC in naïve and treatment-experienced patients.Expert opinion: Data from clinical trials and from real-life show that DTG+3TC is an effective and safe switch option for the treatment of experienced patients. In treatment-naïve patients, DTG+3TC has shown non-inferiority compared to standard 3-drug regimens but is less effective in severely immunocompromised naïve patients (i.e. with a CD4+ cell count below 200 cell/mm3); furthermore, current guidelines have upgraded this dual regimen to recommended first-line strategy, but indicate that it should not be used without genotypic resistance results. Moreover, this regimen is not feasible for HBV-coinfected individuals and should not be used during pregnancy. Currently, out of 2-drug regimens, DTG+3TC is one of clinicians' preferred option as it requires no pharmacokinetic booster, has a low risk of drug interaction, and does not require food intake.

Drug-drug interactions of a two-drug regimen of dolutegravir and lamivudine for HIV treatment

INTRODUCTION

The GEMINI trials have recently shown that a two-drug regimen of dolutegravir plus lamivudine was non-inferior to a three-drug regimen in HIV-infected naïve patients. Accordingly, it is important that physicians be aware and confident about the drug-drug interactions (DDIs) involving dolutegravir, lamivudine, and other medications. Areas covered: Here, we firstly update the available information on the pharmacokinetic features of dolutegravir and lamivudine; subsequently, the articles mainly deals with the predictable DDIs for both antiretroviral drugs, attempting to underline their clinical implications. This review focuses on the DDIs of dolutegravir/lamivudine combined regimen and, therefore, does not provide an exhaustive list of all the potential DDIs involving the two single agents. A MEDLINE Pubmed search for articles published from January 2000 to December 2018 was completed matching the terms dolutegravir or lamivudine with pharmacokinetics, DDIs, and pharmacology. Moreover, additional studies were identified from the reference list of retrieved articles. Expert opinion: The antiretroviral dual regimen of dolutegravir and lamivudine represents an attractive therapeutic option for HIV in terms of DDIs. This is particularly relevant considering that the population with HIV is aging and is increasingly experience age-related comorbidities, increasing pill burden, polypharmacy and the risk of DDIs.

Pharmacokinetic Considerations with the Use of Antiepileptic Drugs in Patients with HIV and Organ Transplants

PURPOSE OF REVIEW

Antiepileptic drugs are frequently administered to patients with HIV infection or in recipients of organ transplants. The potentially serious drug-drug interactions between the "classic" antiepileptic drugs, antiretrovirals, and immunosuppressants have been extensively studied. Evidence-based information on the second and third generation of antiepileptic drugs is almost non-existent. The purpose of this review is to analyze the pharmacokinetic profile of these newer agents to assess their potential for drug interactions with antiretrovirals and immunosuppressants.

RECENT FINDINGS

As a group, the newer generations of antiepileptic drugs have shown a more favorable drug interaction potential compared to the "classic" ones. A group of moderate enzyme-inducing drugs includes eslicarbazepine acetate, oxcarbazepine, rufinamide, and topiramate. These drugs are not as potent inducers as the "classic" drugs but may potentially decrease the serum concentrations of some antiretrovirals and immunosuppressants. Antiepileptic drugs with no or minimal enzyme-inducing properties include brivaracetam, gabapentin, lacosamide, lamotrigine, levetiracetam, perampanel, pregabalin, and vigabatrin. The newer generations of antiepileptic drugs have expanded the therapeutic options in patients with HIV infection or organ transplants.