Efavirenz
Pronouncation: (EH-fah-VIE-renz)Class: Non-nucleoside reverse transcriptase inhibitor
Trade Names:
Sustiva
- Capsules 50 mg
- Capsules 100 mg
- Capsules 200 mg
- Tablets 600 mg
Pharmacology
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Noncompetitive inhibition of HIV-1 reverse transcriptase.
Pharmacokinetics
Absorption
C max is 1.6 to 9.1 mcM. T max is 3 to 5 h. Food significantly increases the AUC and C max . Take on empty stomach.
Distribution
Approximately 99.5% is protein bound, predominantly albumin.
Metabolism
Metabolized in the liver by CYP-450 (primarily CYP3A4 and CYP2B6) to inactive metabolites.
Elimination
The t ½ is 52 to 76 h (single-dose) and 40 to 55 h (multiple doses). Approximately 14% to 34% is excreted in the urine (less than 1% as unchanged drug), and 16% to 61% is excreted in the feces.
Indications and Usage
Treatment of HIV-1 infection in combination with other antiretroviral agents.
Contraindications
Concomitant use with cisapride, ergot derivatives, midazolam, or triazolam; hypersensitivity to product.
Dosage and Administration
AdultsPO 600 mg/day in combination with other antiretroviral agents.
Children 10 to less than 15 kgPO 200 mg/day in combination with other antiretroviral agents.
Children 15 to less than 20 kgPO 250 mg/day in combination with other antiretroviral agents.
Children 20 to less than 25 kgPO 300 mg/day in combination with other antiretroviral agents.
Children 25 to less than 32.5 kgPO 350 mg/day in combination with other antiretroviral agents.
Children 32.5 to less than 40 kgPO 400 mg/day in combination with other antiretroviral agents.
Children at least 40 kgPO 600 mg/day in combination with other antiretroviral agents.
General Advice
Administer at bedtime initially and when CNS symptoms are present to improve tolerance of these symptoms.
Storage/Stability
Store oral capsules and tablets at room temperature (77°F); excursions permitted (59° to 86°F).
Drug Interactions
Alprazolam, midazolam, triazolamMay increase blood levels of these drugs, which may produce extreme sedation and respiratory depression. Do not administer concurrently.
Clarithromycin, indinavir, methadone, saquinavirEfavirenz may decrease plasma concentrations, which could reduce activity of these agents.
Cisapride, ergot derivativesMay elevate levels of these drugs, which may increase the risk of arrhythmias, hematologic abnormalities, or other potentially serious adverse reactions. Do not coadminister.
Ethinyl estradiol, nelfinavir, ritonavirEfavirenz may increase plasma concentrations, which could increase activity or toxicity of these agents.
Phenytoin, carbamazepine, phenobarbitalPlasma concentrations of the anticonvulsant or efavirenz may decrease.
RifampinMay decrease plasma levels of efavirenz, which may reduce antiviral activity.
RitonavirMay increase efavirenz plasma level, which could increase adverse reactions.
St. John's wortMay reduce efavirenz plasma concentrations, which may decrease the clinical efficacy.
WarfarinPlasma concentrations may be increased or decreased.
Laboratory Test Interactions
False-positive urine assay screening test for cannabinoid may occur.
Adverse Reactions
Cardiovascular
Flushing; palpitations.
CNS
Dizziness (28.1%); fatigue; headache; hypesthesia; impaired concentration (8.3%); insomnia (16.3%); abnormal dreams (6.2%); somnolence (7%); depression; anorexia; nervousness; ataxia; confusion; impaired coordination; paresthesia; neuropathy; tremor; agitation; emotional lability; hallucination; psychosis.
Dermatologic
Maculopapular rash; rash (26.3%; eg, blistering, desquamation, mucosal involvement, fever); pruritus; increased sweating.
EENT
Abnormal vision; tinnitus.
GI
Nausea; vomiting; diarrhea; dyspepsia; abdominal pain.
Hepatic
Hepatitis; LFT elevation.
Metabolic
Increased total cholesterol; increased amylase.
Respiratory
Cough; dyspnea.
Miscellaneous
Arthralgia; myalgia; asthenia; fever; pain.
Precautions
Pregnancy
Category C .
Lactation
HIV-infected mothers should not breast-feed their infants.
Children
Ongoing study.
CNS symptoms
Reported in 53% of patients.
Hepatitis
Monitor liver enzymes in patients with known or suspected history of hepatitis B or C infection and in patients receiving medication associated with liver toxicity.
Monotherapy
Resistant virus may emerge rapidly.
Psychiatric symptoms
Serious adverse psychiatric experiences have been reported. Patients with a prior history of psychiatric disorders may be at greater risk. There have been occasional reports of death by suicide, delusions, and psychosis-like behavior.
Skin rash
Reported in 26% of adults and 46% of children.
Overdosage
Symptoms
Increased CNS symptoms, muscle contractions.
Patient Information
- Instruct patient to take efavirenz at the same time each day as prescribed in combination with other antiviral drugs and not to skip doses, which could increase the viral load.
- Inform patient not to alter the dose or discontinue therapy without consulting health care provider.
- Inform patient that efavirenz may cause dizziness, impaired concentration, or drowsiness, and to avoid potentially hazardous tasks such as driving or operating machinery if experiencing these symptoms.
- Inform patient that dosing at bedtime improves the tolerability of CNS symptoms.
- Alert patient to the potential for additive CNS effects when efavirenz is used concomitantly with alcohol or psychoactive drugs.
- Caution patient or family that long-term effects and adverse reactions are not known. Therefore, report any problems to the primary care provider.
- Warn patient of the potential adverse reactions and drug/drug interactions.
- Instruct patient to notify health care provider immediately if signs of rash or rash accompanied by fever, blistering, oral lesions, conjunctivitis, swelling, muscle or joint aches, general malaise, infection such as a sore throat, fever, cough, or respiratory congestion occur.
- Instruct patient to notify health care provider immediately if symptoms of serious psychiatric adverse reactions occur.
- Inform patient of potential false-positive urine cannabinoid test results.
- Inform patient that efavirenz has not been shown to reduce the risk of passing HIV to others through sexual contact or blood contamination. Encourage abstinence or practicing safe sex and not sharing needles.
- Advise women to use barrier contraception in combination with other methods of contraception (eg, oral or other hormonal contraceptives).
- Caution mothers to discontinue nursing while receiving efavirenz as there is potential for adverse reactions from the drug in nursing infants and transmission of the HIV virus.
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More Efavirenz resources:
Efavirenz - Includes detailed dosage instructions.
HIV Infection, Nonoccupational Exposure, Occupational Exposure
