Title: Efavirenz
CAS Registry Number: 154598-52-4
CAS Name: (4S)-6-Chloro-4-(cyclopropylethynyl)-1,4-dihydro-4-(trifluoromethyl)-2H-3,1-benzoxazin-2-one
Manufacturers' Codes: DMP-266
Trademarks: Stocrin (Merck & Co.); Sustiva (BMS)
Molecular Formula: C14H9ClF3NO2
Molecular Weight: 315.67
Percent Composition: C 53.27%, H 2.87%, Cl 11.23%, F 18.06%, N 4.44%, O 10.14%
Literature References: Nonnucleoside HIV-1 reverse transcriptase inhibitor. Prepn: S. D. Young et al., EP 582455; eidem, US 5519021 (1994, 1996 both to Merck & Co.). Pharmacology: S. D. Young et al., Antimicrob. Agents Chemother. 39, 2602 (1995). Enantioselective synthesis: A. S. Thompson et al., Tetrahedron Lett. 36, 8937 (1995). Total synthesis and resolution of enantiomers: L. A. Radesca et al., Synth. Commun. 27, 4373 (1997). Ionization behavior: S. R. Rabel et al., Pharm. Dev. Technol. 1, 91 (1996). Clinical trial as component of combination therapy in HIV-1 infection in adults: S. Staszewski et al., N. Engl. J. Med. 341, 1865 (1999); in children: S. E. Starr et al., ibid. 1874. Review of clinical experience: C. Fortin, V. Joly, Expert Rev. Anti Infect. Ther. 2, 671-684 (2004).
Properties: Crystals from toluene:heptane, mp 139-141°. [a]D20 -84.7° (c = 0.005 g/ml in CH3Cl). [a]D25 -94.1° (c = 0.300 in methanol). pKa 10.2.
Melting point: mp 139-141°
pKa: pKa 10.2
Optical Rotation: [a]D20 -84.7° (c = 0.005 g/ml in CH3Cl); [a]D25 -94.1° (c = 0.300 in methanol)
Therap-Cat: Antiviral.
Keywords: Antiviral; Reverse Transcriptase Inhibitor.
Eflornithine Efloxate Efonidipine Efrotomycin EGCG

Systematic (IUPAC) name
Clinical data
Trade names Sustiva, Stocrin etc.
AHFS/Drugs.com monograph
MedlinePlus a699004
Pregnancy cat. D (U.S.)
Legal status POM (UK), ℞-only (U.S.)
Routes Oral
Pharmacokinetic data
Protein binding 99.5-99.75%
Metabolism Hepatic (CYP2A6 and CYP2B6-mediated)
Half-life 40-55 hours
Excretion Renal and fecal
CAS number 154598-52-4 YesY
ATC code J05AG03
PubChem CID 64139
DrugBank DB00625
ChemSpider 57715 YesY
KEGG D00896 YesY
ChEBI CHEBI:119486 YesY
NIAID ChemDB 032934
Chemical data
Formula C14H9ClF3NO2 
Mol. mass 315.675 g/mol
 YesY (what is this?)  (verify)

Efavirenz (EFV, brand names Sustiva, Stocrin, Efavir etc.) is a non-nucleoside reverse transcriptase inhibitor (NNRTI) and is used as part of highly active antiretroviral therapy (HAART) for the treatment of a human immunodeficiency virus (HIV) type 1.

For HIV infection that has not previously been treated, the United States Department of Health and Human Services Panel on Antiretroviral Guidelines currently recommends the use of efavirenz in combination with tenofovir/emtricitabine (Truvada) as one of the preferred NNRTI-based regimens in adults and adolescents.[1]

Efavirenz is also used in combination with other antiretroviral agents as part of an expanded postexposure prophylaxis regimen to reduce the risk of HIV infection in people exposed to a significant risk (e.g. needlestick injuries, certain types of unprotected sex etc.).

The usual adult dose is 600 mg once a day. It is usually taken on an empty stomach at bedtime to reduce neurological and psychiatric adverse effects.

Efavirenz was combined with the popular HIV medication Truvada, which consists of tenofovir and emtricitabine, all of which are reverse transcriptase inhibitors. This combination of three medications approved by the U.S. Food and Drug Administration (FDA) in July 2006 under the brand name Atripla, provides HAART in a single tablet taken once a day. It results in a simplified drug regimen for many patients.