We don't have synonyms for rifampin yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are rifampicin, rifamycin and rifadin.
(n) :
(pharmacology) US form of rifampicin. [(pharmacology) A reddish-brown semisynthetic antibiotic C₄₃H₅₈N₄O₁₂ obtained from the bacterium Amycolaptosis mediterranei, used chiefly to treat tuberculosis, leprosy, and asymptomatic carriers of meningococci.]
(n) :
(pharmacology) US form of rifampicin. [(pharmacology) A reddish-brown semisynthetic antibiotic C₄₃H₅₈N₄O₁₂ obtained from the bacterium Amycolaptosis mediterranei, used chiefly to treat tuberculosis, leprosy, and asymptomatic carriers of meningococci.]