Overview
11 DESCRIPTION Efavirenz, USP is an HIV-1 specific, non-nucleoside, reverse transcriptase inhibitor (NNRTI). Efavirenz is chemically described as(S)-6-chloro-4-(cyclopropylethynyl)-1,4-dihydro4(trifluoromethyl)-2H-3,1-benzoxazin-2-one. Its empirical formula is C 14 H 9 ClF 3 NO 2 and its structural formula is: Efavirenz,USP is a white to slightly pink crystalline powder with a molecular mass of...
Mechanism of Action
12 CLINICAL PHARMACOLOGY 12.1 Mechanism of Action Efavirenz is an antiviral drug [see Microbiology ( 12.4 )]. 12.2 Pharmacodynamics Cardiac Electrophysiology The effect of efavirenz on the QTc interval was evaluated in an open-label, positive and placebo controlled, fixed single sequence 3-period, 3-treatment crossover QT study in 58 healthy subjects enriched for CYP2B6 polymorphisms. The mean Cmax of efavirenz in subjects with CYP2B6 *6/*6 genotype following the administration of 600 mg daily dose for 14 days was 2.25-fold the mean Cmax observed in subjects with CYP2B6 *1/*1 genotype. A positive relationship between efavirenz concentration and QTc prolongation was observed.
Indications
- 1 INDICATIONS & USAGE Efavirenz in combination with other antiretroviral agents is indicated for the treatment of human immunodeficiency virus type 1 (HIV-1) infection in adults and in pediatric patients at least 3 months old and weighing at least 3.5 kg. Efavirenz is a non-nucleoside reverse transcriptase inhibitor indicated in combination with other antiretroviral agents 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.( 1 )
Common Doses
- 600 mg
- 800 mg
- 400 mg
- 300 mg
Dosage
2 DOSAGE & ADMINISTRATION • Efavirenz should be taken orally once daily on an empty stomach, preferably at bedtime. ( 2 ) • Recommended adult dose: 600 mg. ( 2.2 ) • With rifampin, increase efavirenz dose to 800 mg once daily for patients weighing 50 kg or more. ( 2.2 ) • Pediatric dosing is based on weight. ( 2.3 ) 2.1 Hepatic Function Monitor hepatic function prior to and during treatment with efavirenz [ see Warnings and Precautions ( 5.9 ) ]. Efavirenz is not recommended in patients with moderate or severe hepatic impairment (Child Pugh B or C) [ see Warnings and Precautions ( 5.
Contraindications
- 4 CONTRAINDICATIONS • Efavirenz is contraindicated in patients with previously demonstrated clinically significant hypersensitivity (e.g., Stevens-Johnson syndrome, erythema multiforme, or toxic skin eruptions) to any of the components of this product. • Coadministration of efavirenz with elbasvir and grazoprevir is contraindicated [ see Warnings and Precautions ( 5.1 ) and Drug Interactions ( 7.1 ) ]. •Patients with previously demonstrated hypersensitivity (e.g., Stevens-Johnson syndrome, erythema multiforme, or toxic skin eruptions to any of the components of this product.
Side Effects
- 6 ADVERSE REACTIONS The most significant adverse reactions observed in patients treated with efavirenz are: •psychiatric symptoms [see Warnings and Precautions ( 5.5 )], •nervous system symptoms [see Warnings and Precautions ( 5.6 )], •rash [see Warnings and Precautions ( 5.8 )]. •hepatotoxicity [see Warnings and Precautions ( 5.9 )] Most common adverse reactions (>5%, moderate-severe) are impaired concentration, abnormal dreams, rash, dizziness, nausea, headache, fatigue, insomnia, and vomiting.
Interactions
- 7 DRUG INTERACTIONS Coadministration of efavirenz can alter the concentrations of other drugs and other drugs may alter the concentrations of efavirenz. The potential for drug-drug interactions should be considered before and during therapy. ( 7 ) 7.1 Potential for efavirenz to Affect other Drugs Efavirenz has been shown in vivo to induce CYP3A and CYP2B6. Other compounds that are substrates of CYP3A or CYP2B6 may have decreased plasma concentrations when coadministered with efavirenz 7.2 Potential for Other Drugs to Affect efavirenz Drugs that induce CYP3A activity (e.g.