Absence seizures associated with efavirenz initiation

The Pharmacogenetics of Efavirenz Metabolism in Children: The Potential Genetic and Medical Contributions to Child Development in the Context of Long-Term ARV Treatment

Efavirenz (EFV) is a well-known, effective anti-retroviral drug long used in first-line treatment for children and adults with HIV and HIV/AIDS. Due to its narrow window of effective concentrations, between 1 and 4 μg/mL, and neurological side effects at supratherapeutic levels, several investigations into the pharmacokinetics of the drug and its genetic underpinnings have been carried out, primarily with adult samples. A number of studies, however, have examined the genetic influences on the metabolism of EFV in children. Their primary goal has been to shed light on issues of appropriate pediatric dosing, as well as the manifestation of neurotoxic effects of EFV in some children. Although EFV is currently being phased out of use for the treatment of both adults and children, we share this line of research to highlight an important aspect of medical treatment that is relevant to understanding the development of children diagnosed with HIV.

Neuropsychiatric and Neurocognitive Manifestations in HIV-Infected Children Treated With Efavirenz in South Africa-A Retrospective Case Series

Background: Efavirenz is associated with transient neuropsychiatric manifestations but the impact on neurocognition in children is unknown. Genetically slow metabolizers of efavirenz may be at risk of toxicity. This study describes neuropsychiatric and neurocognitive manifestations of South African children with suspected efavirenz neurotoxicity. Method: This retrospective study describes clinical features of 12 children with features consistent with efavirenz neurotoxicity between 2008 and 2014. Results: Twelve children (4 males, 8 females) aged 3-12 years (median 8.4 years) were referred to a dedicated pediatric neuroHIV service. Eight were of indigenous African (black) ancestry and 4 were of mixed ancestry. The total duration on efavirenz-containing ART at the time of referral was 6-72 (mean 31) months. Two children (both of black ancestry) were phenotypically slow metabolizers and presented with acute manifestations and high plasma efavirenz concentrations above normal range resulting in discontinuation of efavirenz. Ten other children had clinical presentations compatible with efavirenz neurotoxicity but had normal or sub-therapeutic plasma efavirenz concentrations and continued treatment with efavirenz. The acute neuropsychiatric manifestations reported included drowsiness, seizures, sleep disturbances, personality changes, ataxia, and slurred speech. These were noticed 2-8 weeks (mean 5 weeks) after commencing efavirenz and resolved over a few weeks. Nine children had neurocognitive deficits and showed poor performance in all neurocognitive domains that were tested. Interpretation: Efavirenz causes transient neuropsychiatric adverse effects and may contribute to poor long-term neurocognitive outcomes in HIV-infected children. Prospective studies comparing efavirenz-treated and efavirenz-naïve children are needed to further elucidate the manifestations of efavirenz toxicity.

Seizures in Children with HIV infection in South Africa: A retrospective case control study

PURPOSE

Data relating to the role that Human immunodeficiency virus (HIV) contributes towards seizures in HIV-infected children is limited. The management of seizures in this group is complex due to potential interactions between antiseizure medication and antiretroviral therapies. This study explores the seizure semiology and course of a population of affected children based on questions raised from a previous epidemiological study.

METHODS

A retrospective case-control study of all patients presenting to an HIV neurology clinic between 2008-2015 was conducted. A multinomial logistic regression model was used to identify risk factors for seizure occurrence in HIV-infected children, as well as factors associated with seizure control.

RESULTS

Of 227 HIV-infected children (median 82 months, interquartile range 41-109), 52 (23%) reported a past or present history of seizures. Prior bacterial meningitis (p =  0.03, OR 12.5, 95% CI 1.2-136.1), cerebrovascular accident (CVA, p =  0. 005, OR 8.1, 95% CI 1.9-34.9) and or tuberculous meningitis (TBM, p =  0.0004) was associated with an increased risk of seizures in HIV-infected children. Generalised tonic-clonic seizures were the predominant seizure type (64%) with the majority caused by an infectious aetiology (62%). Thirty-two (62%) of these patients had epilepsy in-line with the latest diagnostic criteria. HIV-infected children with epilepsy who were treated with efavirenz were more likely to have poor seizure control (OR 23.1 95% CI 3.4-159.6, p =  0.0001).

CONCLUSIONS

This study provides new data highlighting the complex clinical presentation and management challenges of HIV-infected children with seizures.

Neuropsychiatric complications of efavirenz in children with HIV infection

Efavirenz is an effective antiretroviral agent widely used as part of first-line regimen in HIV1-infected children and adults. Neuropsychiatric adverse effects are reported in up to 50% of users. These include dizziness, insomnia, abnormal dreams, headache and impaired concentration. The plasma level of efavirenz may be key in the development of these adverse effects. Even among individuals taking recommended doses for weight, the plasma levels vary widely. Genetic polymorphisms leading to different allelic variants of the CYP2B6 enzyme, making some individuals slow metabolizers may play a role. These allelic variants are highest in people of African descent. This report examines the neuropsychiatric adverse effects of efavirenz, and the strength of the data that the product may result in neuronal damage.

A 33-year-old patient with human immunodeficiency virus on antiretroviral therapy with efavirenz-induced complex partial seizures: a case report

Background

Efavirenz is a commonly prescribed antiretroviral drug that is largely well tolerated. However, seizure disorder is a rare side effect. Prompt identification and immediate replacement of efavirenz with an alternative drug would effectively stop the seizures. To the best of our knowledge, we present the first reported case in the literature of complex partial seizures arising due to efavirenz.

Case presentation

We report a case of a 33-year-old Nigerian man treated with an efavirenz-based antiretroviral regimen for human immunodeficiency virus infection. He presented with seizures soon after commencement of antiretroviral drugs. His magnetic resonance imaging results were unremarkable. His blood levels of sodium, glucose, urea, and creatinine were within normal limits. However, his electroencephalogram showed intermittent bursts of high-voltage sharp waves and spikes bilaterally over frontotemporoparietal regions, a finding consistent with complex partial seizures. His efavirenz plasma level was 209.55 μg/ml. His seizures stopped following a switch to a non-efavirenz-based regimen.

Conclusions

This report brings to light the occurrence of complex partial seizures in patients on efavirenz. It also demonstrates the effective resolution of seizures when efavirenz treatment is replaced with a non-efavirenz-based regimen.

Case report: Severe central nervous system manifestations associated with aberrant efavirenz metabolism in children: the role of CYP2B6 genetic variation

Background

Efavirenz, widely used as part of antiretroviral drug regimens in the treatment of paediatric human immunodeficiency virus infection, has central nervous system side effects. We describe four children presenting with serious, persistent central nervous system adverse events who were found to have elevated plasma efavirenz concentrations as a result of carrying CYP2B6 single nucleotide polymorphisms, known to play a role in the metabolism of EFV. None of the children had a CYP2B6 wildtype haplotype. We believe this is the first case of cerebellar dysfunction associated with efavirenz use to be described in children.

Case presentation

Four black African children, between the ages of 4 and 8 years presenting between 1 and 20 months post-efavirenz initiation, are described. Cerebellar dysfunction, generalised seizures and absence seizures were the range of presenting abnormalities. Plasma efavirenz levels ranged from 20-60 mg/L, 5–15 times the upper limit of the suggested reference range. All abnormal central nervous system manifestations abated after efavirenz discontinuation.

Conclusion

Efavirenz toxicity should always be considered in human immunodeficiency virus-infected children with unexplained central nervous system abnormalities. Our findings further our understanding of the impact of genetic variants on antiretroviral pharmacokinetics in children across various ethnic groups. Screening for potential EFV-toxicity based on the CYP2B6 c.516 SNP alone, may not be adequate.

Efavirenz-Based Antiretroviral Therapy Among Nevirapine-Exposed HIV-Infected Children in South Africa: A Randomized Clinical Trial

IMPORTANCE

Advantages of using efavirenz as part of treatment for children infected with human immunodeficiency virus (HIV) include once-daily dosing, simplification of co-treatment for tuberculosis, preservation of ritonavir-boosted lopinavir for second-line treatment, and harmonization of adult and pediatric treatment regimens. However, there have been concerns about possible reduced viral efficacy of efavirenz in children exposed to nevirapine for prevention of mother-to-child transmission.

OBJECTIVE

To evaluate whether nevirapine-exposed children achieving initial viral suppression with ritonavir-boosted lopinavir-based therapy can transition to efavirenz-based therapy without risk of viral failure.

DESIGN, SETTING, AND PARTICIPANTS

Randomized, open-label noninferiority trial conducted at Rahima Moosa Mother and Child Hospital, Johannesburg, South Africa, from June 2010 to December 2013, enrolling 300 HIV-infected children exposed to nevirapine for prevention of mother-to-child transmission who were aged 3 years or older and had plasma HIV RNA of less than 50 copies/mL during ritonavir-boosted lopinavir-based therapy; 298 were randomized and 292 (98%) were followed up to 48 weeks after randomization.

INTERVENTIONS

Participants were randomly assigned to switch to efavirenz-based therapy (n = 150) or continue ritonavir-boosted lopinavir-based therapy (n = 148).

MAIN OUTCOMES AND MEASURES

Risk difference between groups in (1) viral rebound (ie, ≥1 HIV RNA measurement of >50 copies/mL) and (2) viral failure (ie, confirmed HIV RNA >1000 copies/mL) with a noninferiority bound of -0.10. Immunologic and clinical responses were secondary end points.

RESULTS

The Kaplan-Meier probability of viral rebound by 48 weeks was 0.176 (n = 26) in the efavirenz group and 0.284 (n = 42) in the ritonavir-boosted lopinavir group. Probabilities of viral failure were 0.027 (n = 4) in the efavirenz group and 0.020 (n = 3) in the ritonavir-boosted lopinavir group. The risk difference for viral rebound was 0.107 (1-sided 95% CI, 0.028 to ∞) and for viral failure was -0.007 (1-sided 95% CI, -0.036 to ∞). We rejected the null hypothesis that efavirenz is inferior to ritonavir-boosted lopinavir (P < .001) for both end points. By 48 weeks, CD4 cell percentage was 2.88% (95% CI, 1.26%-4.49%) higher in the efavirenz group than in the ritonavir-boosted lopinavir group.

CONCLUSIONS AND RELEVANCE

Among HIV-infected children exposed to nevirapine for prevention of mother-to-child transmission and with initial viral suppression with ritonavir-boosted lopinavir-based therapy, switching to efavirenz-based therapy compared with continuing ritonavir-boosted lopinavir-based therapy did not result in significantly higher rates of viral rebound or viral failure. This therapeutic approach may offer advantages in children such as these.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01146873.

Cytochrome P450 pharmacogenetics in African populations: implications for public health

INTRODUCTION

Africa harbors a disproportionate burden of disease when taking into account the triple challenge caused by HIV/AIDS, tuberculosis (TB) and malaria, against a backdrop of an increasing burden of noncommunicable diseases. More than 80% of therapeutic drugs used in the management of these diseases/conditions are metabolized by CYP enzymes that exhibit genetic polymorphisms.

AREAS COVERED

There is variability in the expression and activities of CYPs resulting in interindividual differences in the response to standard doses of therapeutic drugs, due to genetic polymorphisms, which exhibit both quantitative and qualitative differences between racial and between ethnic groups. The review aims to evaluate the implications of the genetic variation in CYPs on the public health of Africans. The CYPs reviewed here metabolize most of the commonly used therapeutic drugs and include CYP1A2, 2A6, 2B6, 2C8, 2C9, 2C19, 2D6, 3A4 and 3A5. Allele frequencies are compared between African ethnic groups and among populations of African, Asian and European origin. Data are obtained from our own studies and literature.

EXPERT OPINION

The variability in the pattern of genetic variation between populations translates into differences in drug response. Understanding CYP variability improves rational drug use and has public health significance.

Safe Treatment of Seizures in the Setting of HIV/AIDS

OPINION STATEMENT

HIV(+) patients are at increased risk for developing seizures due to the vulnerability of the central nervous system to HIV-associated diseases, immune dysfunction, and metabolic disturbances. In patients with acute seizures, standard protocols still apply with urgent seizure cessation being the priority. Management of the person with established epilepsy who contracts HIV is challenging, but the decision to initiate chronic antiepileptic drug (AED) therapy in an HIV(+) patient is also difficult. Chronic treatment guidelines emphasize the interactions between AEDs and antiretroviral (ARV) medications, but provide no explicit advice regarding when to initiate an AED, what medication to select, and/or the duration of treatment. Epidemiologic data regarding seizure recurrence risk in HIV(+) individuals is not available. The risk of further seizures likely depends upon the underlying etiology for the seizure(s) and patients' immune status and may be increased by the use of efavirenz (an ARV). The issues for consideration include AED-ARV interactions, organ dysfunction, seizure type, and drug side effects, which may worsen or be confused with symptoms of HIV and/or epilepsy. Co-administration of enzyme inducing (EI)-AEDs and ARVs can result in virological failure, breakthrough seizure activity, AED toxicity, and/or ARV toxicity. Where available, the AED of choice in HIV(+) patients is levetiracetam due to its broad spectrum activity, ease of use, minimal drug interactions, and favorable side effect profile. Lacosamide, gabapentin, and pregabalin are also favored choices in patients with partial onset seizures and/or those failing levetiracetam. Where newer AEDs are not available, valproic acid may be the treatment of choice in terms of an AED, which will not cause enzyme induction-associated ARV failure, but its side effect profile causes other obvious problems. In resource-limited settings (RLS) where only EI-AEDs are available, there are no good treatment options and further pressure needs to be placed upon policymakers to address this care gap and public health threat.

Effectiveness of efavirenz-based regimens in young HIV-infected children treated for tuberculosis: a treatment option for resource-limited settings

BACKGROUND

Antiretroviral treatment (ART) options for young children co-infected with HIV and tuberculosis are limited in resource-poor settings due to limited data on the use of efavirenz (EFV). Using available pharmacokinetic data, an EFV dosing schedule was developed for young co-infected children and implemented as the standard of care at Macha Hospital in Southern Province, Zambia. Treatment outcomes in children younger than 3 years of age or weighing less than 10 kg receiving either EFV-based ART plus anti-tuberculous treatment or nevirapine-based (NVP) ART were compared.

METHODS

Treatment outcomes were measured in a cohort of HIV-infected children seeking care at Macha Hospital in rural Zambia from 2007 to 2010. Information on the diagnosis and treatment of tuberculosis was abstracted from medical records.

RESULTS

Forty-five children treated for tuberculosis initiated an EFV-based regimen and 69 children initiated a NVP-based regimen, 7 of whom also were treated for tuberculosis. Children receiving both regimens were comparable in age, but children receiving EFV started ART with a lower CD4(+) T-cell percentage and weight-for-age z-score. Children receiving EFV experienced increases in both CD4(+) T-cell percentage and weight-for-age z-score during follow-up, such that levels were comparable to children receiving NVP after two years of ART. Cumulative survival after 12 months of ART did not differ between groups (NVP:87%;EFV:80%;p = 0.25). Eleven children experienced virologic failure during follow-up.The adjusted hazard ratio of virologic failure comparing EFV to NVP was 0.25 (95% CI:0.05,1.24) and 0.13 (95% CI:0.03,0.62) using thresholds of 5000 and 400 copies/mL, respectively.Five children receiving EFV were reported to have had convulsions after ART initiation compared to only one child receiving NVP (p = 0.04).

CONCLUSIONS

Despite poorer health at ART initiation, children treated for tuberculosis and receiving EFV-based regimens showed significant improvements comparable to children receiving NVP-based regimens. EFV-based regimens should be considered for young HIV-infected children co-infected with tuberculosis in resource-limited settings.

Recent advances in pharmacovigilance of antiretroviral therapy in HIV-infected and exposed children

PURPOSE OF REVIEW

Antiretroviral therapy (ART) has greatly improved the survival of HIV-infected children. However, ART is associated with immediate and long-term adverse events. Pharmacovigilance systems, although imperfect, have been developed in many high-income countries (HICs), but coverage in low- and middle-income countries (LMICs) is poor and uneven. This review covers the recent advances in the understanding of adverse events following perinatal ART exposure, including surveillance from birth cohorts; we also describe the adverse events of antiretroviral drugs among HIV-infected children, focussing particularly on those relevant to LMICs, where more than 90% of HIV-infected children live.

RECENT FINDINGS

ART is largely safe in both HIV-infected and HIV-exposed uninfected children, in whom no significant increase in birth defects has been noted. Among HIV-infected children, toxicity to some drugs may be less frequent than in adults, possibly related to immature immune systems in younger children. As per WHO guidelines, many countries are moving from stavudine-based to zidovudine-based or abacavir-based fixed-dose combination (with nevirapine/lamivudine) paediatric mini-pills. However, reassuring data are emerging about short-term stavudine use in LMICs, as this remains an important first-line regimen for young children, as well as an alternative to zidovudine for anaemic children. Zidovudine appears to be well tolerated in young children living in nonmalarious areas, and, among African children, concerns about abacavir hypersensitivity have not been substantiated.

SUMMARY

Optimization of first-line ART regimens needs to take account of the toxicities in HIV-infected children, in particular as they will take ART much longer than adults and during the period of growth and development. The benefits of ART in pregnancy are clear, but long-term follow-up of ART-exposed infants in LMICs through integrated surveillance systems would be invaluable.