Efavirenz

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Contents

[edit] BRAND NAMES


Combinations:

  • Efavirenz/Emtricitabine/Tenofovir: Atripla

[edit] STRUCTURE

Efavirenz.jpg

[edit] MECHANISM OF ACTION

Efavirenz is a non-nucleoside reverse transcriptase inhibitor (NNRTI)

[edit] INDICATIONS

Efavirenz is indicated in combination with with tenofovir/emtricitabine (Truvada) for the treatment of human immunodeficiency virus type 1 infection in adults and in pediatric patients at least 3 months old and weighing at least 3.5 kg (FDA)

[edit] DOSAGE

Efavirenz should be taken orally once daily on an empty stomach, preferably at bedtime to reduce neurological and psychiatric adverse effects.

  • Recommended adult dose: 600 mg.
  • Pediatric dosing is based on weight: 

Patient Body Weight

Sustiva Daily Dose

Number of Capsules a or Tablets band Strength to Administer

3.5 kg to less than 5 kg

100 mg

two 50 mg capsules

5 kg to less than 7.5 kg

150 mg

three 50 mg capsules

7.5 kg to less than 15 kg

200 mg

one 200 mg capsule

15 kg to less than 20 kg

250 mg

one 200 mg + one 50 mg capsule

20 kg to less than 25 kg

300 mg

one 200 mg + two 50 mg capsules

25 kg to less than 32.5 kg

350 mg

one 200 mg + three 50 mg capsules

32.5 kg to less than 40 kg

400 mg

two 200 mg capsules

at least 40 kg

600 mg

one 600 mg tablet OR
three 200 mg capsules

[edit] DOSAGE FORMS AND STRENGTHS

  • Capsules: 200 mg and 50 mg
  • Tablets: 600 mg

[edit] CONTRAINDICATIONS

  • Patients with previously demonstrated hypersensitivity (eg, Stevens-Johnson syndrome, erythema multiforme, or toxic skin eruptions) to the drug.


  • Drugs that are contraindicated with Efavirenz:
    • Anti-migraine (ergot derivatives): dihydroergotamine, ergotamine, Ergonovine (Potential for serious and/or life-threatening reactions such as acute ergot toxicity characterized by peripheral vasospasm and ischemia of the extremities and other tissues)
    • Benzodiazepines: midazolam, triazolam (Potential for serious and/or life-threatening reactions such as prolonged or increased sedation or respiratory depression)
    • Gastrointestinal motility drugs: Cisapride (Potential for serious and/or life-threatening reactions such as cardiac arrhythmias).
    • Calcium channel blocker: bepridil (Potential for serious and/or life-threatening reactions such as cardiac arrhythmias)
    • Neuroleptic: pimozide (Potential for serious and/or life-threatening reactions such as cardiac arrhythmias)
    • St. John’s wort (Hypericum perforatum) (May lead to loss of virologic response and possible resistance to efavirenz or to the class of non-nucleoside reverse transcriptase inhibitors (NNRTIs))

[edit] PRECAUTIONS

  • Do not use as a single agent or add on as a sole agent to a failing regimen. Consider potential for cross resistance when choosing other agents.
  • Not recommended with ATRIPLA, which contains efavirenz, emtricitabine, and tenofovir disoproxil fumarate, unless needed for dose adjustment when coadministered with rifampin.
  • Serious psychiatric symptoms: Immediate medical evaluation is recommended for serious psychiatric symptoms such as severe depression or suicidal ideation.
  • Nervous system symptoms (NSS): NSS are frequent, usually begin 1-2 days after initiating therapy and resolve in 2-4 weeks. Dosing at bedtime may improve tolerability. NSS are not predictive of onset of psychiatric symptoms.
  • Pregnancy: Fetal harm can occur when administered to a pregnant woman during the first trimester. Women should be apprised of the potential harm to the fetus. Pregnancy registry is available.
  • Hepatotoxicity: Monitor liver function tests before and during treatment in patients with underlying hepatic disease, including hepatitis B or C coinfection, marked transaminase elevations, or who are taking medications associated with liver toxicity. Among reported cases of hepatic failure, a few occurred in patients with no pre-existing hepatic disease.
  • Rash: Rash usually begins within 1-2 weeks after initiating therapy and resolves within 4 weeks. Discontinue if severe rash develops.
  • Convulsions: Use caution in patients with a history of seizures.
  • Lipids: Total cholesterol and triglyceride elevations. Monitor before therapy and periodically thereafter.
  • Immune reconstitution syndrome: May necessitate further evaluation and treatment.
  • Redistribution/accumulation of body fat: Observed in patients receiving antiretroviral therapy

[edit] INTERACTIONS

CYP2B6 and CYP3A4

  • Efavirenz is an inducer of the CYP2B6 and CYP3A4. Compounds that are substrates of these enzymes may have decreased plasma concentrations when co-administered with efavirenz
  • Efavirenz is also a substrate of the CYP2B6 and CYP3A4; Efavirenz exposure may be increased when given with medicinal products (for example, ritonavir) or food (for example, grapefruit juice), which inhibit CYP3A4 or CYP2B6 activity.
  • Compounds or herbal preparations (for example Ginkgo biloba extracts and St. John’s wort) which induce these enzymes may give rise to decreased plasma concentrations of efavirenz. Concomitant use of St. John’s

wort is contraindicated. Concomitant use of Ginkgo biloba extracts is not recommended

Efavirenz lowers blood levels of most protease inhibitors. Dosages of amprenavir, atazanavir, or indinavir may need to be increased. The blood levels of saquinavir are dramatically lowered

[edit] PREGNANCY AND LACTATION

Pregnancy Category D (US): The clinical benefit of efavirenz outweighs the potential carcinogenic risk to humans.

[edit] SIDE EFFECTS

Psychiatric symptoms, including abnormal dreams, anxiety, depression, insomnia, are common, and more serious symptoms such as affect lability, aggression, confusional state, euphoric mood, hallucination, mania, paranoia, psychosis, , suicide attempt and suicide ideation are uncommon.

Rash, pruritus, abdominal pain, diarrhea, nausea, vomiting, hypertriglyceridemia, fatigue and headache are also common

[edit] RELATED LINKS

[edit] BIBLIOGRAPHY

[edit] REFERENCES