Estiva 600mg Tablet

Estiva 600mg Tablet (Efavirenz) – Generic Sustiva by Hetero Drugs | HIV-1 NNRTI Antiretroviral

Reviewed by a licensed physician | Last updated: April 2026 Prescription required | NPPA regulated | Always used in combination with other antiretrovirals | Never as monotherapy

What It Is

Estiva 600mg contains Efavirenz 600mg — an oral non-nucleoside reverse transcriptase inhibitor (NNRTI) and the active molecule in branded Sustiva® (Bristol Myers Squibb, USA) and Stocrin® (MSD/Merck, Europe/Africa). Manufactured by Hetero Drugs Ltd (Hyderabad, India) — one of India's largest antiretroviral producers and a major WHO-prequalified ARV supplier globally.

Other Indian brands at the same 600mg strength include: Efavir (Cipla), Efcure (Sun Pharma), Viranz (Aurobindo). All contain identical active substance.

Important clinical context: Efavirenz 600mg was the WHO preferred first-line HIV-1 treatment until June 2018. It was replaced as preferred by dolutegravir (DTG) due to superior tolerability and resistance profile. However, efavirenz 600mg remains a WHO-listed alternative with specific clinical roles where it is still the right choice — explained below.

When Efavirenz Is Still the Right Choice in 2025

Efavirenz 600mg is not obsolete — it remains clinically appropriate and WHO-recommended in specific situations:

This is the honest clinical picture — and it is what buyers and prescribers actually need to know.

How It Works

HIV replicates by converting its RNA genome into DNA using the enzyme reverse transcriptase. This DNA then integrates into the host cell's genome, producing new virus. Efavirenz is an NNRTI — it binds to a specific allosteric pocket on reverse transcriptase (not the active site), locking the enzyme in a non-functional conformation. This blocks DNA synthesis and stops HIV replication.

Unlike NRTIs (nucleoside analogues that compete at the active site), efavirenz's allosteric binding means it does not require intracellular activation and has a rapid onset of action. Plasma efavirenz levels reach steady state within 6–7 days of once-daily dosing.

Efavirenz does not cure HIV. It suppresses viral load to undetectable levels in combination with other antiretrovirals, preserving CD4 cell count and immune function, and preventing AIDS-defining illness.

Dosage

Always take at bedtime on an empty stomach. This is the most important administration instruction. CNS side effects (dizziness, vivid dreams, insomnia) are most intense in the first 2–4 weeks — taking at bedtime means patients sleep through the worst of them. High-fat meals increase efavirenz absorption by up to 50%, increasing CNS side effect risk.

Always combined with 2 NRTIs — standard backbone: Tenofovir + Lamivudine (TDF/3TC) or Tenofovir + Emtricitabine (TDF/FTC). Fixed-dose combinations (Vonavir, Atripla, Trustiva: TDF + FTC + EFV) are available and preferred for adherence.

Side Effects

CNS effects — the defining characteristic of efavirenz: Dizziness, vivid dreams or nightmares, insomnia, difficulty concentrating, and a "floating" or dissociative sensation occur in 52% of patients in the first 2–4 weeks. These are predictable, manageable, and resolve in most patients within 4 weeks. Bedtime dosing significantly reduces impact. Patients must be counselled before starting — these effects are alarming if unexpected but harmless and temporary for most.

Common: Rash (usually mild, weeks 1–2, usually resolves without stopping treatment). Nausea. Raised liver enzymes.

Serious — report immediately: Severe rash with blistering or mucosal involvement (rare Stevens-Johnson syndrome). Severe depression, suicidal ideation, or psychosis — particularly in patients with pre-existing mental health conditions. Jaundice or severe liver enzyme elevation. Persistent CNS symptoms beyond 4 weeks at full intensity.

Pregnancy: Efavirenz has been associated with neural tube defects in early pregnancy in animal studies. Avoid in the first trimester. If pregnancy is detected during efavirenz treatment, do not abruptly stop — discuss with HIV specialist. Post-first-trimester use is generally considered acceptable.

FAQ

Is Estiva the same as Sustiva? Yes — identical active molecule (efavirenz 600mg), manufactured by Hetero Drugs in a WHO-GMP facility. Same mechanism, same efficacy.

Has efavirenz been replaced by dolutegravir? Dolutegravir is now the WHO preferred first-line NNRTI alternative. However, efavirenz 600mg remains WHO-recommended for TB-HIV coinfection with rifampicin, for stable patients already on it, and where DTG is unavailable. It is not obsolete.

Why does efavirenz cause vivid dreams? Efavirenz crosses the blood-brain barrier and has activity at CNS receptors — producing the characteristic neuropsychiatric effects. Taking it at bedtime means the peak concentration occurs during sleep, significantly reducing waking impact. Most patients find these effects greatly diminish after 2–4 weeks.

Can I take Estiva with food? Take on an empty stomach at bedtime. High-fat meals significantly increase absorption and intensify CNS side effects — particularly in the first weeks of treatment.

Is Estiva used for HIV-2? No. Efavirenz is not effective against HIV-2 — the NNRTI binding pocket in HIV-2 reverse transcriptase has a different structure that confers intrinsic resistance to the entire NNRTI class.

References

1. Estiva 600mg — Hetero Healthcare Official Product Page https://www.heterohealthcare.com/estiva-600-tablet
2. Efavirenz — DrugBank DB00625 (NNRTI mechanism, pharmacokinetics, interactions) https://go.drugbank.com/drugs/DB00625
3. WHO Consolidated Guidelines on HIV Prevention, Testing, Treatment, Service Delivery and Monitoring — WHO 2021. Dolutegravir as preferred; efavirenz as alternative including TB coinfection. https://www.who.int/publications/i/item/9789240031593
4. Dolutegravir or Low-Dose Efavirenz — NAMSAL ANRS 12313 Trial — NEJM (2019) https://www.nejm.org/doi/full/10.1056/NEJMoa1904340
5. Comparative efficacy of dolutegravir vs efavirenz — Network meta-analysis supporting WHO guidelines — ScienceDirect (2020) https://www.sciencedirect.com/science/article/pii/S2589537020303175