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Efavirenz (Sustiva)

Antiretroviralprescriptionoral · inferred

First-generation non-nucleoside reverse transcriptase inhibitor (NNRTI); 600 mg PO once daily at bedtime. Long plasma half-life (~40-55h) enables once-daily dosing. Oral bioavailability ~50%; highly protein bound. Strong CYP2B6 metabolism with CYP2B6 516G>T polymorphism driving large exposure variability. Potent CYP3A4 inducer generating many drug interactions. Prominent CNS adverse effects (vivid dreams, dizziness, mood changes) typically improve after 2-4 weeks; rare suicidality signal. Teratogenic in animals.

Projected serum levels — 600 mg, once daily

Efavirenz (Sustiva)
Efavirenz (Sustiva) modeled serum levels, 600 mg once daily over 18 days Population-based pharmacokinetic estimate. Steady state reached after approximately 6 days. 0 500 1k 1.5k 2k Day 0 Day 5 Day 9 Day 14 Day 18 Time on a regular schedule ≈ steady state · day 6
Efavirenz (Sustiva) modeled serum levels with a loading dose of 1.8k mg, then 600 mg once daily The first dose is larger so levels approach steady state faster. 0 500 1k 1.5k 2k Day 0 Day 5 Day 9 Day 14 Day 18 Time on a regular schedule

Maintenance schedule: 600 mg once daily (oral).

Loading schedule: 1.8k mg on day 1, then 600 mg once daily — reaching therapeutic levels sooner.

Modeled steady state after ~6 days: peak ≈ 1.0k mg, trough ≈ 776 mg body load. Population-based estimate over 18 days for a 600 mg dose at a 70 kg reference body mass — the interactive app scales curves to your doses, timing, and body mass.

Key facts

Category
Antiretroviral
Route modeled
Oral
Model confidence
inferred
Half-life
2.2 days
Common dose
600 mg
Suggested maximum
600 mg/day
Reference dose range
200–600 mg (single dose)
Suggested cadence
once daily
Validated against
600 mg oral — Cmax 4.1 mg/L at 5 h

Documented interactions

  • contraindicated
    7-Hydroxymitragynine (7-OH) + Efavirenz (Sustiva) CYP induction

    Efavirenz (Sustiva) inducer of CYP3A4 predicted to change 7-Hydroxymitragynine (7-OH) AUC by ~0.16x

  • contraindicated
    Albendazole (Albenza) + Efavirenz (Sustiva) CYP induction

    Efavirenz (Sustiva) inducer of CYP3A4 predicted to change Albendazole (Albenza) AUC by ~0.18x

  • contraindicated
    Alfuzosin (Uroxatral) + Efavirenz (Sustiva) CYP induction

    Efavirenz (Sustiva) inducer of CYP3A4 predicted to change Alfuzosin (Uroxatral) AUC by ~0.12x

  • contraindicated
    Alprazolam (Xanax) + Efavirenz (Sustiva) CYP induction

    Efavirenz (Sustiva) inducer of CYP3A4 predicted to change Alprazolam (Xanax) AUC by ~0.12x

  • contraindicated
    Amlodipine (Norvasc) + Efavirenz (Sustiva) CYP induction

    Efavirenz (Sustiva) inducer of CYP3A4 predicted to change Amlodipine (Norvasc) AUC by ~0.12x

  • contraindicated
    Anastrozole (Arimidex) + Efavirenz (Sustiva) CYP induction

    Efavirenz (Sustiva) inducer of CYP3A4 predicted to change Anastrozole (Arimidex) AUC by ~0.14x

Serum checks 559 modeled interaction pairings for efavirenz (sustiva) across your whole stack — absorption conflicts, enzyme inhibition, and nutrient depletion included.

Research behind this entry

  1. Efavirenz plasma levels can predict treatment failure and central nervous system side effects in HIV-1-infected patients Marzolini C et al. · AIDS, 2001 DOI

    Seminal exposure-response analysis linking efavirenz plasma concentrations to both virologic failure (low) and CNS toxicity (high), establishing therapeutic range ~1000-4000 ng/mL.

  2. Population pharmacokinetics and effects of CYP2B6 polymorphisms on efavirenz plasma concentrations in HIV-infected patients Csajka C et al. · Clinical Pharmacology & Therapeutics, 2003 DOI

    Population PK analysis identifying CYP2B6 genotype as a major determinant of efavirenz clearance and exposure variability.

2 published studies referenced in the app, each with a plain-language summary.