Efavirenz biotransformation as an up-stream event of mood changes in HIV-infected patients

Quantification of Efavirenz Hydroxymetabolites in Human Plasma Using LC-HRMS/MS

BACKGROUND

Efavirenz (EFV) is a drug used to treat HIV. Low plasma concentrations of EFV result in suboptimal viral suppression, whereas high concentrations can cause adverse neuropsychiatric side reactions. Some studies have identified a correlation between the plasma concentrations of EFV metabolites and neurotoxicity. To our knowledge, no studies have investigated the metabolism of EFV in young children and its effect on treatment outcomes. Therefore, the aim of this study was to develop and validate a method for quantifying EFV and its metabolites in human plasma derived from children.

METHODS

Sample preparation was performed using protein precipitation of 100 µL plasma. Thereafter, an aliquot of the supernatant was used to quantify EFV, 7-hydroxyefavirenz (7-OH-EFV), 8-hydroxyefavirenz (8-OH-EFV), and a newly discovered metabolite ("EFAdeg") associated with 8-OH-EFV. A second aliquot of the supernatant was hydrolyzed using β-glucuronidase/arylsulfatase and used with the first aliquot to quantify phase II metabolites. The analyses were performed using a Dionex Ultimate 3000RS LC-system coupled with a Q Exactive Orbitrap mass spectrometer.

RESULTS

The method has a measuring range of 100-50,000 ng/mL (EFV, 8-OH-EFV), 125-25,000 ng/mL (7-OH-EFV), and 200-10,000 ng/mL ("EFAdeg"). All criteria of the European Medicines Agency guidelines regarding precision, accuracy, and selectivity were met. Of note, carryover must be considered for 8-OH-EFV. Overall, the validated method was successfully applied to plasma samples obtained from children and confirmed the presence of the newly discovered metabolite, "EFAdeg."

CONCLUSIONS

An LC-HRMS/MS method for the quantification of EFV and its phase I and II metabolites was developed and validated. This method is suitable for analyzing plasma samples from children. Furthermore, studies using this method identified an additional metabolite that may influence the concentration of 8-OH-EFV in patient samples.

Influence of efavirenz and 8-hydroxy-efavirenz plasma levels on cognition and central nervous system side effects

OBJECTIVES

To investigate whether efavirenz (EFV) or 8-hydroxy-EFV (8-OH-EFV) plasma levels are associated with neurocognitive impairment and central nervous system (CNS) side effects.

METHODS

We conducted a cross-sectional analysis to explore the potential links between EFV/8-OH-EFV levels and cognitive performance or CNS-related side effects in patients screened within a randomized trial involving a switch from EFV to rilpivirine. The Mann-Whitney test was employed to compare drug levels in patients with or without cognitive impairment, depression, anxiety, sleep disorder or CNS symptoms. Additionally, Spearman's test was used to assess correlations between drug levels and test scores.

RESULTS

Among 104 patients, neither EFV nor 8-OH-EFV levels were linked to cognitive impairment, although trends towards higher EFV levels were observed in those with impaired executive function (p = 0.055) and language performances (p = 0.021). On the other hand, elevated 8-OH-EFV levels, but not EFV levels, were associated with more CNS side effects (222 vs. 151 ng/mL, p = 0.027), depressive symptoms (247 vs. 164 ng/mL, p = 0.067) and sleep impairment (247 vs. 164 ng/mL, p = 0.078). Consistently, a trend towards a correlation between EFV levels and lower z-scores in executive function and motor function was observed, while 8-OH-EFV levels, but not EFV levels, were directly correlated with symptom scores.

CONCLUSIONS

Higher levels of 8-OH-EFV were associated with CNS side effects, while EFV levels were only marginally associated with cognitive performance, thus suggesting that EFV and its metabolite may act differently in determining detrimental neurological effects.

Biotransformation of Efavirenz and Proteomic Analysis of Cytochrome P450s and UDP-Glucuronosyltransferases in Mouse, Macaque, and Human Brain-Derived In Vitro Systems

Antiretroviral drugs such as efavirenz (EFV) are essential to combat human immunodeficiency virus (HIV) infection in the brain, but little is known about how these drugs are metabolized locally. In this study, the cytochrome P450 (P450) and UDP-glucuronosyltransferase (UGT)-dependent metabolism of EFV was probed in brain microsomes from mice, cynomolgus macaques, and humans as well as primary neural cells from C57BL/6N mice. Utilizing ultra high performance liquid chromatography high-resolution mass spectrometry (uHPLC-HRMS), the formation of 8-hydroxyefavirenz (8-OHEFV) from EFV and the glucuronidation of P450-dependent metabolites 8-OHEFV and 8,14-dihydroxyefavirenz (8,14-diOHEFV) were observed in brain microsomes from all three species. The direct glucuronidation of EFV, however, was only detected in cynomolgus macaque brain microsomes. In primary neural cells treated with EFV, microglia were the only cell type to exhibit metabolism, forming 8-OHEFV only. In cells treated with the P450-dependent metabolites of EFV, glucuronidation was detected only in cortical neurons and astrocytes, revealing that certain aspects of EFV metabolism are cell type specific. Untargeted and targeted proteomics experiments were used to identify the P450s and UGTs present in brain microsomes. Eleven P450s and 11 UGTs were detected in human brain microsomes, whereas seven P450s and 14 UGTs were identified in mouse brain microsomes and 15 P450s and four UGTs, respectively, were observed in macaque brain microsomes. This was the first time many of these enzymes have been noted in brain microsomes at the protein level. This study indicates the potential for brain metabolism to contribute to pharmacological and toxicological outcomes of EFV in the brain. SIGNIFICANCE STATEMENT: Metabolism in the brain is understudied, and the persistence of human immunodeficiency virus (HIV) infection in the brain warrants the evaluation of how antiretroviral drugs such as efavirenz are metabolized in the brain. Using brain microsomes, the metabolism of efavirenz by both cytochrome P450s (P450s) and UDP-glucuronosyltransferases (UGTs) is established. Additionally, proteomics of brain microsomes characterizes P450s and UGTs in the brain, many of which have not yet been noted in the literature at the protein level.

Algae-mediated processes for the treatment of antiretroviral drugs in wastewater: Prospects and challenges

The prevalence of pharmaceuticals (PCs), especially antiretroviral (ARV) drugs in various aquatic ecosystems has been expansively reported, wherein wastewater treatment plants (WWTPs) are identified as the primary point source. Consequently, the occurrence, ecotoxicity and treatment of ARV drugs in WWTPs have drawn much attention in recent years. Numerous studies have shown that the widely employed activated sludge-based WWTPs are incapable of removing ARV drugs efficiently from wastewater. Recently, algae-based wastewater treatment processes have shown promising results in PCs removal from wastewater, either completely or partially, through different processes such as biosorption, bioaccumulation, and intra-/inter-cellular degradation. Algal species have also shown to tolerate high concentrations of ARV drugs than the reported concentrations in the environmental matrices. In this review, emphasis has been given on discussing the current status of the occurrence of ARV drugs in the aquatic environment and WWTPs. Besides, the current trends and future perspectives of PCs removal by algae are critically reviewed and discussed. The potential pathways and mechanisms of ARV drugs removal by algae have also been discussed.

A simple method to measure sulfonation in man using paracetamol as probe drug

Sulfotransferase enzymes (SULT) catalyse sulfoconjugation of drugs, as well as endogenous mediators, gut microbiota metabolites and environmental xenobiotics. To address the limited evidence on sulfonation activity from clinical research, we developed a clinical metabolic phenotyping method using paracetamol as a probe substrate. Our aim was to estimate sulfonation capability of phenolic compounds and study its intraindividual variability in man. A total of 36 healthy adult volunteers (12 men, 12 women and 12 women on oral contraceptives) received paracetamol in a 1 g-tablet formulation on three separate occasions. Paracetamol and its metabolites were measured in plasma and spot urine samples using liquid chromatography-high resolution mass spectrometry. A metabolic ratio (Paracetamol Sulfonation Index—PSI) was used to estimate phenol SULT activity. PSI showed low intraindividual variability, with a good correlation between values in plasma and spot urine samples. Urinary PSI was independent of factors not related to SULT activity, such as urine pH or eGFR. Gender and oral contraceptive intake had no impact on PSI. Our SULT phenotyping method is a simple non-invasive procedure requiring urine spot samples, using the safe and convenient drug paracetamol as a probe substrate, and with low intraindividual coefficient of variation. Although it will not give us mechanistic information, it will provide us an empirical measure of an individual’s sulfonator status. To the best of our knowledge, our method provides the first standardised in vivo empirical measure of an individual’s phenol sulfonation capability and of its intraindividual variability. EUDRA-CT 2016-001395-29, NCT03182595 June 9, 2017.

Pharmacogenomics and pharmacokinetics of efavirenz 400 or 600 mg in 184 treatment-naive HIV-infected patients in China

Background: The pharmacogenomics and pharmacokinetics/pharmacodynamics of 400 mg efavirenz have rarely been reported. Materials & methods: A total of 184 treatment-naive HIV-infected patients were randomly assigned (1:1) to receive a lower dose (tenofovir disoproxil 200 mg, efavirenz 400 mg and lamivudine) or a standard dose regimen. Relationships between pharmacogenomics and efavirenz pharmacokinetics/pharmacodynamics were explored at 48 weeks. Results: There was no relationship between pharmacogenomics and adverse reactions of the central nervous system and antiretoviral efficacy. CYP2B6 516G>T, 785A>G, 18492C>T and ABCB1 3435C>T T/C were associated with higher efavirenz plasma levels in the standard but not the lower dose group. No relationship was found between pharmacogenomics and antiretoviral efficacy. Patients who were <60 kg had higher efavirenz concentration compared with those with weight ≥60 kg when using 600 mg efavirenz, this was not observed with 400 mg efavirenz. Conclusion: The effect of pharmacogenomics and body weight on the efavirenz concentration was significant in the 600 mg group but not in the 400 mg group.

Efavirenz and Efavirenz-like Compounds Activate Human, Murine, and Macaque Hepatic IRE1α-XBP1

Efavirenz (EFV), a widely used antiretroviral drug, is associated with idiosyncratic hepatotoxicity and dyslipidemia. Here we demonstrate that EFV stimulates the activation in primary hepatocytes of key cell stress regulators: inositol-requiring 1α (IRE1α) and X-box binding protein 1 (XBP1). Following EFV exposure, XBP1 splicing (indicating activation) was increased 35.7-fold in primary human hepatocytes. In parallel, XBP1 splicing and IRE1α phosphorylation (p-IRE1α, active IRE1α) were elevated 36.4-fold and 4.9-fold, respectively, in primary mouse hepatocytes. Of note, with EFV treatment, 47.2% of mouse hepatocytes were apoptotic; which was decreased to 23.9% in the presence of STF 083010, an inhibitor of XBP1 splicing. Experiments performed using pregnane X receptor (PXR)-null mouse hepatocytes revealed that EFV-mediated XBP1 splicing and hepatocyte death were not dependent on PXR, which is a nuclear receptor transcription factor that plays a crucial role in the cellular response to xenobiotics. Interestingly, incubation with the primary metabolite of EFV, 8-hydroxyefavirenz (8-OHEFV), only resulted in 10.3- and 2.9-fold increased XBP1 splicing in human and mouse hepatocytes and no change in levels of p-IRE1α in mouse hepatocytes. To further probe the structure-activity relationship of IRE1α-XBP1 activation by EFV, 16 EFV analogs were employed. Of these, an analog in which the EFV alkyne is replaced with an alkene and an analog in which the oxazinone oxygen is replaced by a carbon stimulated XBP1 splicing in human, mouse, and macaque hepatocytes. These data demonstrate that EFV and compounds sharing the EFV scaffold can activate IRE1α-XBP1 across human, mouse, and macaque species.

Unmasking efavirenz neurotoxicity: Time matters to the underlying mechanisms

Efavirenz is an anti-HIV drug that presents relevant short- and long-term central nervous system adverse reactions. Its main metabolite (8-hydroxy-efavirenz) was demonstrated to be a more potent neurotoxin than efavirenz itself. This work was aimed to understand how efavirenz biotransformation to 8-hydroxy-efavirenz is related to its short- and long-term neuro-adverse reactions. To access those mechanisms, the expression and activity of Cyp2b enzymes as well as the thiolomic signature (low molecular weight thiols plus S-thiolated proteins) were longitudinally evaluated in the hepatic and brain tissues of rats exposed to efavirenz during 10 and 36days. Efavirenz and 8-hydroxy-efavirenz plasma concentrations were monitored at the same time points. Cyp2b induction had a delayed onset in liver (p<0.001), translating into increases in Cyp2b activity in liver and 8-hydroxy-efavirenz plasma concentration (p<0.001). Moreover, an increase in S-cysteinyl-glycinylated proteins (p<0.001) and in free low molecular weight thiols was also observed in liver. A distinct scenario was observed in hippocampus, which showed an underexpression of Cyp2b as well as a decrease in S-cysteinylated and S-glutathionylated proteins. Additionally, the observed changes in tissues were associated with a marked increase of S-glutathionylation in plasma. Our data suggest that the time course of efavirenz biotransformation results from different mechanisms for its short- and long-term neurotoxicity. The difference in the redox profile between liver and hippocampus might explain why, despite being mostly metabolized by the liver, this drug is neurotoxic. If translated to clinical practice, this evidence will have important implications in efavirenz short- and long-term neurotoxicity prevention and management.