Efavirenz is the most potent non-nucleoside reverse transcriptase inhibitor given orally to treat human immunodeficiency virus infection. The standard dosage is 600 mg once daily, taken in combination therapy.
This drug is contraindicated in the periconceptional period and during pregnancy, as suggested by animal teratology studies. In 3 (15%) of 20 pregnant cynomolgus monkeys, exposed at therapeutic doses similar to those used for humans, efavirenz produced the following malformations: anencephaly with unilateral anophthalmia (1 case), microphthalmia (1 case), and cleft palate (1 case).1,2 The manufacturer (DuPont Pharmaceuticals Company, Wilmington, Del) recommends that women who take efavirenz avoid pregnancy, and the drug is classified by the US Food and Drug Administration in pregnancy category C.1,2
De Santis M, Carducci B, De Santis L, Cavaliere AF, Straface G. Periconceptional Exposure to Efavirenz and Neural Tube Defects. Arch Intern Med. 2002;162(3):355-356. doi: