Efavirenz 400 mg Shows Noninferiority to 600 mg in Treatment-Naïve Chinese PatientsTrial shows lower dose of efavirenz works for HIV treatment

International journal of infectious diseases : IJID : official publication of the International Society for Infectious Diseases Published September 5, 2026 Study authors: Hang Qi, Ziyan Wang, Xiaojing Song, Min Wang, Haibo Ding, Hanhui Ye, Zhihao Meng, Shenghua He, Yun H… PubMed ↗ NCT04463784 ↗ DOI ↗ Editorial oversight: Dr. Amelia Tan, PhD · Internal Medicine & Chronic Disease

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Key Takeaway

Efavirenz 400 mg is noninferior to 600 mg for virological suppression while offering a superior safety profile.

This multicenter randomized controlled trial evaluated the efficacy and safety of two different efavirenz dosages in 422 treatment-naïve Chinese adults with HIV-1. Patients were randomized to receive either 400 mg or 600 mg of efavirenz combined with lamivudine and tenofovir. The primary endpoint was virological suppression, defined as HIV-RNA levels below 50 copies/ml at week 72.

Results demonstrated that 86.5% of patients receiving 400 mg achieved virological suppression compared to 84.1% in the 600 mg cohort. This difference was not statistically significant (p=0.57), indicating that the lower dose is noninferior to the standard 600 mg dose for maintaining viral suppression over the 72-week period.

Safety profiles revealed significant differences in tolerability. The 600 mg group experienced a significantly higher incidence of serious non-rash adverse events. Additionally, the 400 mg dose was associated with lower rates of drug discontinuation. These findings suggest that the 400 mg dose provides a viable, well-tolerated alternative for managing HIV-1 in this population.

How this fits prior evidence

How this fits prior evidence: This finding addresses a gap in optimal dosing for efavirenz in treatment-naïve populations. While previous coverage confirmed that dolutegravir and lamivudine achieved 78% HIV-1 RNA suppression in patients with isolated reactive anti-HBc, and that dolutegravir-based regimens showed comparable viral suppression rates at week 48, this study specifically addresses the noninferiority of a lower efavirenz dose. It provides a specific comparison for efavirenz dosing that was not covered in the previously discussed dolutegravir or bictegravir regimens.

Researchers conducted a multicenter trial involving 422 treatment-naïve Chinese adults living with HIV-1. The study compared two different doses of the medication efavirenz when combined with lamivudine and tenofovir. One group received 400 mg of efavirenz, while the other received 600 mg.

At the 72-week mark, the results showed that 86.5% of patients in the 400 mg group achieved virological suppression, compared to 84.1% in the 600 mg group. This small difference was not considered statistically significant. This means both doses were effective at keeping the virus at low levels in the blood.

However, the study did find differences in safety. The group taking the higher 600 mg dose had a significantly higher number of serious non-rash side effects. While the 400 mg dose was reported to have better tolerability, the long-term effects of reducing the dose beyond 48 weeks are not fully known. Patients should discuss these specific dosage options and safety profiles with their healthcare provider.

What this means for you:

A 400 mg dose of efavirenz showed similar effectiveness to a 600 mg dose but with fewer serious side effects.

Common questions

Is the lower dose of efavirenz as effective as the higher dose?

Yes, the study found that the 400 mg dose was not significantly different from the 600 mg dose in terms of virological suppression. At 72 weeks, 86.5% of the 400 mg group and 84.1% of the 600 mg group achieved the target of having fewer than 50 copies of HIV-RNA per ml.

Are there safety concerns with the higher dose of efavirenz?

The study reported that the 600 mg dose group had a significantly higher incidence of serious non-rash adverse events. While the 400 mg dose was noted for better tolerability, the long-term safety of lower doses beyond 48 weeks is not fully known.

Who was included in this study?

The study included 422 Chinese adults who were treatment-naïve, meaning they had not previously received treatment for HIV-1. The study followed these participants for at least 72 weeks to monitor both the effectiveness and the safety of the medications.

Study Details

Study typeRct

Sample sizen = 422

EvidenceLevel 2

Follow-up11.1 mo

PublishedSep 2026

PMID42235914

TrialNCT04463784

View Original Abstract ↓

BACKGROUND: Optimizing efavirenz (EFV) dosing to minimize adverse events (AEs) remains a critical issue. Studies indicate that reducing the EFV dose from 600 to 400 mg daily lowers side effect intensity while maintaining virological suppression. We previously showed that 600 mg daily EFV may lead to unnecessarily high exposure in Chinese patients, but the long-term efficacy and safety of dose reduction beyond 48 weeks in this population remain unknown. METHODS: We conducted a multicenter, randomized controlled trial comparing EFV 400 vs 600 mg, each combined with lamivudine (3TC) and tenofovir (TDF), in antiretroviral therapy-naïve Chinese adults with human immunodeficiency virus (HIV)-1. The primary endpoint was virological suppression (HIV-ribonucleic acid [RNA] <50 copies/ml) at week 72. A total of 422 participants were randomized (215 in the 400 mg group, 207 in the 600 mg group); 334 (169 and 165, respectively) completed the week 72 primary endpoint assessment, while an optional extension to week 96 was conducted for exploratory analyses. RESULTS: At baseline, demographic and clinical characteristics were comparable between groups. At week 72, virological suppression (HIV-RNA <50 copies/ml) was achieved in 86.5% (186/215) of the EFV 400 mg group and 84.1% (174/207) of the EFV 600 mg group (difference +2.5 percentage points, 95% confidence interval -4.3 to 9.2, P = 0.57), meeting the noninferiority criteria. While overall AE profiles were comparable, the EFV 600 mg group exhibited a significantly higher incidence of serious nonrash AEs (P = 0.042), and a numerically higher but nonsignificant rate of drug discontinuation due to AEs (4.8% vs 1.9%, P = 0.094). CONCLUSION: EFV 400 mg is noninferior to EFV 600 mg in treatment-naïve Chinese patients over 72 weeks, offering improved safety and tolerability. TRIAL REGISTRATION: #NCT04463784 on ClinicalTrials.gov, Registered by Peking Union Medical College Hospital on April 1, 2018 (URL: https://clinicaltrials.gov/study/NCT04463784).

Efavirenz 400 mg Shows Noninferiority to 600 mg in Treatment-Naïve Chinese PatientsTrial shows lower dose of efavirenz works for HIV treatment

How this fits prior evidence

Common questions

Study Details

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Efavirenz 400 mg Shows Noninferiority to 600 mg in Treatment-Naïve Chinese PatientsTrial shows lower dose of efavirenz works for HIV treatment

How this fits prior evidence

Common questions

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