Yes. Efavirenz may be taken with or without food. A high-fat meal can slightly increase absorption, which might intensify central nervous system effects for some individuals.
In the UK, the 200 mg tablet typically bears the imprint “EF 200” and the 600 mg tablet “EF 600”. Imprints help verify authenticity when compared with the packaging insert.
Efavirenz is not a controlled substance and is not screened for in standard workplace drug testing panels. However, any antiretroviral medication will be listed on a medical questionnaire if required.
Yes. Efavirenz is marketed as a generic tablet by multiple manufacturers. The active ingredient and dosage are identical; only the branding differs.
Both belong to the NNRTI class, but efavirenz has a longer half-life allowing once-daily dosing, whereas nevirapine often requires twice-daily dosing. Efavirenz is more commonly associated with vivid dreams and CNS side effects, while nevirapine has a higher risk of hepatotoxicity.
Yes, but you should carry a copy of the prescription and a letter from your clinician confirming medical necessity, as some countries require documentation for antiretroviral drugs at customs.
St. John’s wort induces CYP enzymes and can reduce efavirenz concentrations, potentially compromising viral suppression. Patients should discuss any herbal products with their healthcare provider.
Mild rashes can be monitored, but if the rash spreads, is accompanied by fever, or blisters, stop the medication and seek urgent medical attention as it could signal a serious skin reaction.
Because efavirenz can cause dizziness, visual disturbances, or sleep-related side effects, individuals operating aircraft or heavy machinery should assess their response to the medication before performing safety-critical tasks. In the UK, the Civil Aviation Authority requires reporting of any medication that may impair performance.
Most patients achieve an undetectable viral load within 12 weeks when efavirenz is part of a fully suppressive HAART regimen, though individual response may vary based on baseline viral load and adherence.
Sustiva is a brand-name medication that contains efavirenz as its active ingredient. It belongs to the antiretroviral class of drugs used to treat Human Immunodeficiency Virus (HIV) infection. In the United Kingdom, Sustaina is a prescription-only medicine (POM) regulated by the Medicines and Healthcare products Regulatory Agency (MHRA). It is supplied as a pill in two strengths: 200 mg and 600 mg.
Efavirenz is a non-nucleoside reverse transcriptase inhibitor (NNRTI). It binds directly to the HIV-1 reverse transcriptase enzyme, blocking the enzyme’s ability to copy viral RNA into DNA. This interruption prevents the virus from replicating inside host cells. The drug is absorbed well after oral administration, reaching peak plasma concentrations within 3-5 hours. Its half-life is long (≈40-55 hours), allowing once-daily dosing. By reducing the amount of circulating virus, efavirenz helps to restore and preserve immune function.
Sustiva is approved by the MHRA for use in combination with other antiretroviral agents as part of highly active antiretroviral therapy (HAART) for:
The medication is not approved for HIV-2 infection or for use as a single-agent therapy.
Major interactions
Ritonavir-boosted protease inhibitors - may increase efavirenz levels, risking toxicity.
CYP2B6 inducers (e.g., carbamazepine, phenobarbital) - can reduce efavirenz concentrations, potentially compromising viral suppression.
Moderate interactions
Azole antifungals (e.g., fluconazole) - may raise efavirenz levels modestly.
Warfarin - efavirenz may alter INR; more frequent monitoring is advised.
Mechanism - most interactions involve the cytochrome P450 enzyme system, particularly CYP2B6 and CYP3A4.
All dosing must be individualized by a qualified healthcare professional.
This article provides educational information about Sustiva and is not a substitute for professional medical advice. Treatment decisions, including use for unapproved indications, must be made under the guidance of a qualified healthcare provider. The content is intended for informational purposes and does not constitute medical recommendations. Always consult a physician before starting, stopping, or changing any medication regimen.
