Pharmacology
Why do some HIV patients get side effects from efavirenz?
Open access · cc by · source: Europe PMC
Most Ugandan patients starting the HIV drug efavirenz had neuropsychiatric side effects such as vivid dreams, and these were linked to higher blood levels of the drug, which in turn depended on a patient's CYP2B6 gene variant, while taking TB drugs at the same time made no difference.
Study at a glance
- Design
- Cohort — Prospective cohort: treatment-naive HIV patients started efavirenz 600 mg daily (plus zidovudine and lamivudine); TB co-infected patients also took rifampicin-based TB therapy. Mid-dose efavirenz levels were measured from day 3 to week 12, five drug-handling genes were genotyped, and neuropsychiatric symptoms were assessed at baseline, week 2 and week 12.
- N
- N=197 · 197 patients: 59 with HIV only on efavirenz alone and 138 with HIV-TB co-infection also receiving rifampicin; 89.9% were assessed at week 12.
- Population
- Newly diagnosed, antiretroviral-naive adults with HIV, with or without tuberculosis, at two national referral hospitals in Kampala, Uganda (2008-2009).
- Outcome
- Incidence and type of neuropsychiatric symptoms (sleep disorders, hallucinations, cognition on an adjusted MMSE) over 12 weeks, and their relation to plasma efavirenz concentration, rifampicin co-treatment and genotype.
Structured fields used in claim comparison tables when every cited study has a complete layer.
Key findings
About 74% of patients developed at least one efavirenz-related neuropsychiatric symptom within 12 weeks, mostly sleep disturbances (60.5%, largely vivid dreams) and hallucinations (30.7%), nearly all starting in the first two weeks. Patients with symptoms had higher plasma efavirenz, and CYP2B6 genotype predicted drug levels at every time point; almost everyone with two copies of the slow-metabolising CYP2B6*6 variant had symptoms, though the direct genotype-symptom link was only a trend. Rifampicin lowered efavirenz levels only in the first week, and symptom rates were almost identical with and without it (74% versus 72%). Cognition actually improved on treatment, with severe cognitive impairment falling from 46 to 22 patients.
Methodology
The researchers followed 197 newly diagnosed HIV patients in Kampala who started efavirenz-based treatment; 138 also had tuberculosis and were taking rifampicin, a drug known to speed up the breakdown of other medicines. They measured efavirenz blood levels repeatedly over the first 12 weeks, genotyped variants in CYP2B6, CYP3A5, CYP2A6, ABCB1 and NR1I3, and had a psychiatric nurse assess sleep problems, hallucinations and cognition at baseline, week 2 and week 12.
Limitations
There was no comparison group of patients on a different HIV drug, so symptoms such as vivid dreams cannot be attributed to efavirenz with certainty, and assessment relied partly on patients' memory of sleep and hallucinations. The study was too small to confirm direct effects of less common gene variants, many results are described only as tendencies, and brain (cerebrospinal fluid) drug levels were not measured. Findings come from one Ugandan population and may not transfer to other African or non-African groups with different gene frequencies.
How this study connects
Role on claims
Each row is a claim on a concept or method page where this paper supports, challenges, or qualifies the statement. Roles are hand-checked — not a model guess.
Genotype mattered more than the TB drug for efavirenz exposure.
TB co-treatment complicates HIV drug therapy less than expected for efavirenz: rifampicin lowered efavirenz levels only in the first week in a Ugandan cohort (symptoms 74% vs 72%), and made no significant difference to clearance in a Zimbabwean population-pharmacokinetic study.
Evidence for the claim as stated.
Exposure links genotype to side effects, imperfectly.
Higher efavirenz exposure tracked neuropsychiatric symptoms in a Ugandan cohort of 197 adults: 74% developed a symptom within 12 weeks, symptomatic patients had higher plasma levels, and CYP2B6 genotype predicted levels at every time point, though the direct genotype-symptom link was only a trend.
Evidence for the claim as stated.
Whether efavirenz levels explain CNS side effects differs between studies: the Ugandan prospective cohort linked higher levels to symptoms, while the Zimbabwean cross-sectional study of patients already on therapy found no difference. Timing matters, as Ugandan symptoms arose mostly in the first two weeks.
Evidence for the claim as stated.
Open questions
Tensions this paper is part of
From concept pages' “where studies disagree.” Disagreement means the same question; scope means different assays, populations, or outcomes.
Whether efavirenz levels explain CNS side effects differs between studies: the Ugandan prospective cohort linked higher levels to symptoms, while the Zimbabwean cross-sectional study of patients already on therapy found no difference. Timing matters, as Ugandan symptoms arose mostly in the first two weeks.
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