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Objectives: Single nucleotide polymorphisms in the cytochrome P450 (CYP) 2B6 gene have been associated with high interindividual variation in efavirenz pharmacokinetics. However, clinical data on the relationship of CYP2B6 polymorphisms with the occurrence of efavirenz-induced central nervous system (CNS) symptoms are limited., Methods: We analysed four polymorphisms in the CYP2B6 (516 G>T), CYP3A5 (6986 A>G) and ATP-binding cassette, sub-family B, member 1 (ABCB1) (2677 G>T/A and 3435 C>T) genes in HIV-infected adults virologically suppressed on a protease inhibitor-based regimen who switched to a regimen containing emtricitabine, didanosine and efavirenz in the setting of the ANRS ALIZE trial. Kaplan-Meier methods and Cox regression analysis were used to investigate their association with efavirenz plasma levels and CNS events up to 48 months after switching., Results: In total, 191 patients with a median age of 41 years, who were 87% male and 85% Caucasian, were enrolled in the study. Variant allelic frequencies were 0.49, 0.93, 0.59 and 0.63 for CYP2B6 516, CYP3A5 392, ABCB1 2677 and ABCB1 3435, respectively. The median efavirenz plasma concentration (MEPC) was 2.2 mg/L [interquartile range (IQR) 1.7-2.8 mg/L] and was significantly higher in patients with the deficient CYP2B6 516T. Overall, 242 CNS events were reported in 104 individuals (54%). No correlation was found between MEPC and CNS events. The occurrence of a first CNS event was lower in patients with the CYP2B6 516 G/G genotype vs. CYP2B6 516 T genotypes [50% (IQR: 40-60%) vs. 66% (IQR: 56-75%), respectively; P = 0.02]. In an adjusted Cox regression model, there was a tendency towards a higher risk of a first CNS event among carriers of the variant CYP2B6 516 T allele (relative risk 1.4 [95% CI, 0.99-2.1]; P?=?.06), compared with noncarriers., Conclusions: The deficient CYP2B6 516 T allele is associated with higher efavirenz plasma drug levels and more frequent CNS-related symptoms., (© 2017 British HIV Association.)

Background: once-daily combinations of efavirenz and two nucleoside analogues are recommended for the treatment of HIV infection. Long-term efficacy and safety data are scarce for the combination of efavirenz, emtricitabine and didanosine., Methods: the ALIZE ANRS 099 trial enrolled 355 adults with plasma HIV RNA levels of <400 copies/mL under a protease inhibitor-based regimen, who were randomized to remain on this regimen or to switch to a once-daily regimen of emtricitabine, didanosine and efavirenz for 48 weeks. An extended 4 year follow-up was available for the 178 patients who switched to the efavirenz-containing regimen, and assessed plasma HIV RNA levels, CD4 cell counts, safety and tolerability., Results: after a median follow-up of 42 months, 121 patients (68%) remained on an efavirenz-based regimen, and 62% and 57% had plasma HIV RNA levels of <400 and <50 copies/mL, respectively, in an intent-to-continue analysis with missing data and treatment discontinuation considered as failure. There was a significant increase in CD4 cell count of 41 cells/mm(3). Drug-related adverse events were the main reason for treatment discontinuation in 26 patients (15%), and 15 were reported during the first year of therapy (58%). There was no emergence of clinically defined lipodystrophy, and lipid and glucose profiles were favourable with a significant increase from baseline of high-density lipoprotein cholesterol levels (median increase 12 mg/dL, P < 10(-4))., Conclusions: a once-daily regimen of emtricitabine, didanosine and efavirenz provided a durable antiretroviral response and was well tolerated through 4 years of therapy.

Background: Once-daily combination therapy with emtricitabine, didanosine and efavirenz has been highly effective in clinical trials but its long-term efficacy and safety has not been previously reported., Methods: This multicentre, single-arm, open-label trial enrolled 40 antiretroviral-naive HIV-1-infected patients who received a once-daily regimen of emtricitabine, didanosine and efavirenz. The objective was to assess the long-term effects of this combination on plasma HIV RNA levels, CD4+ T-cell counts, safety and tolerability., Results: After 5 years, 73% and 68% of patients had plasma HIV RNA levels < 400 and < 50 copies/ml, respectively, in an intent-to-treat, missing-equals-failure analysis. Genotypic resistance on treatment emerged in six patients. There was a significant increase in CD4+ T-cell count of 294 x 10(6) cells/l. Only six patients discontinued study treatment, because of non-severe adverse events. Lipodystrophy was infrequent, and lipid and glucose profiles were favourable with a significant increase in high-density lipoprotein cholesterol., Conclusion: A convenient once-daily regimen of emtricitabine, didanosine and efavirenz provided durable antiretroviral response and was well tolerated through 5 years of therapy.