Rifampicin
Essential component of TB treatment (HRZE regimen) safe to use in pregnancy. No established teratogenicity at standard doses. At term, rifampicin induces fetal CYP enzymes and can deplete vitamin K-dependent clotting factors — administer prophylactic vitamin K (10 mg IM) to the neonate at birth if the mother was on rifampicin near delivery. Also a potent enzyme inducer that reduces levels of many coadministered drugs (e.g., reduces hormonal contraceptive efficacy).
