Efavirenz – HIV Antiviral Therapy

Efavirenz is a potent first-generation non-nucleoside reverse transcriptase inhibitor (NNRTI) that has been a cornerstone of antiretroviral therapy for decades. The drug is well-known for its high virologic efficacy and its ability to penetrate the blood-brain barrier.

The mechanism of action involves direct, non-competitive binding to the HIV-1 reverse transcriptase enzyme. This binding induces conformational changes that block the enzyme's catalytic activity, preventing the conversion of viral RNA into DNA. Unlike nucleoside analogs, efavirenz does not require intracellular phosphorylation to become active. It is highly specific to HIV-1 and does not show activity against HIV-2 or human cellular DNA polymerases.

Due to its long half-life, efavirenz is administered once daily, which significantly supports long-term treatment adherence.

Wikipedia page
Efavirenz

Indications

Efavirenz is indicated for the treatment of HIV-1 infection in adults and pediatric patients:

  • Combination Therapy: must always be used in combination with other antiretroviral agents to prevent the emergence of drug resistance.
  • Co-infected Patients: often preferred for patients undergoing simultaneous treatment for HIV and tuberculosis (due to manageable interactions with rifampin).

Dosage and administration

Strict adherence to administration rules is essential to minimize the side effects of efavirenz.

  • Standard Adult Dose: 600 mg once daily.
  • Timing: it is strongly recommended to take the dose at bedtime on an empty stomach.
  • Food Effect: taking the drug with a high-fat meal significantly increases blood concentrations, leading to a higher frequency of nervous system side effects.
  • Pediatric Dosing: calculated based on body weight (available for children weighing at least 3.5 kg).

The use of efavirenz is contraindicated in the following situations:

  • Hypersensitivity: allergic reactions to efavirenz or any component of the formulation.
  • Severe Hepatic Impairment: due to the risk of toxicity from elevated drug levels.
  • Drug Interactions: co-administration with terfenadine, astemizole, pimozide, St. John's wort, or ergot alkaloids is prohibited.
  • Cardiac Conditions: a family history of QT prolongation or use of medications that prolong the QT interval.

Efavirenz is frequently associated with specific central nervous system reactions:

  • Neuropsychiatric: dizziness, insomnia, abnormal dreams, and impaired concentration (usually resolve after 2–4 weeks).
  • Psychiatric: depression, anxiety, and rarely, psychotic reactions or suicidal ideation.
  • Dermatologic: maculopapular skin rash (usually mild but requires monitoring).
  • Metabolic: increased cholesterol and triglycerides; lipodystrophy.
  • Hepatic: elevation of liver enzymes, particularly in patients co-infected with Hepatitis B or C.

Frequently Asked Questions

Efavirenz is a non-nucleoside reverse transcriptase inhibitor (NNRTI). It blocks the reverse transcriptase enzyme by binding directly to it, which prevents the HIV-1 virus from converting its RNA into DNA. This makes it impossible for the virus to infect new cells and replicate within the body.
The substance frequently causes central nervous system side effects (dizziness, drowsiness). Taking it at bedtime helps the patient "sleep through" the peak of these sensations. It is crucial to take it on an empty stomach because high-fat meals significantly increase absorption, which can worsen toxicity and side effects.
Efavirenz is known to cause vivid or abnormal dreams, hallucinations, confusion, or depressive states. These symptoms typically appear during the first few weeks of therapy and often subside over time. However, patients with a history of psychiatric disorders require close medical supervision.
While there were historical concerns regarding the teratogenicity of efavirenz, current data suggest the risk is not higher than with other antiretrovirals. Nevertheless, use during the first trimester should be evaluated by a physician. Women of childbearing potential are advised to use reliable contraception (barrier methods combined with hormonal ones).
Yes, long-term use of efavirenz can lead to increased levels of total cholesterol and triglycerides in the blood. Patients are advised to have their lipid profiles monitored regularly and, if necessary, follow a diet or take lipid-lowering medications as prescribed.

List of medicines by active substance Efavirenz

-18%
Trustiva 300 mg + 600 mg + 200 mg Hetero
View
Hetero

Trustiva

Tenofovir Disoproxil Fumarate + Efavirenz + Emtricitabine
300 mg + 600 mg + 200 mg 30 tablets
1626₴ 1978₴
-7%
Viraday 600 mg + 200 mg + 300 mg Cipla
View
Cipla

Viraday

Efavirenz + Emtricitabine + Tenofovir Disoproxil Fumarate
600 mg + 200 mg + 300 mg 30 tablets
2197₴ 2373₴
✅ All products loaded (2)

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