Generic and additional names: 5,6,9,17,19,21-hexahydroxy-23-methoxy-2,4,12,16,18,20,22-heptamethyl-8-[N-(4-methyl-1-piperazinyl)formimidoyl]-2,7-(epoxypentadeca[1,11,13]trienimino)naphtho[2,1-b]furan-1,11(2H)-dione 21-acetate; rifampicin; rifaldazine; rifamycin AMP; R/AMP

CAS name: 3-{[(4-Methyl-1-piperazinyl)imino]methyl}rifamycin

CAS registry #: 13292-46-1

Molecular formula: C₄₃H₅₈N₄O₁₂

Molecular weight: 822.94

Intellectual property rights: Generic. Parent compound originally identified as a natural product from Amycolatopsis at Lapetit, Milan, Italy.¹ Lapetit collaborated with Ciba-Geigy in the early development of this compound.¹

Brand names: Rifampin, rifampicin, rifamycin. Abrifam (Abbott); Eremfat (Fatol); Rifa (Grüunenthal); Rifadin(e), Rifaldin (Aventis); Rifapiam (Piam); Rifaprodin (Almirall); Rifoldin (Aventis); Rimactan(e) (Novartis)

Derivatives: Rifapentine, rifalazil, rifabutin

Solubility: Freely soluble in chloroform and DMSO; soluble in ethyl acetate, methanol, tetrahydrofuran; slightly soluble in acetone, water, carbon tetrachloride [Merck Index]

Polarity: Log P 3.719 [DrugBank]

Acidity/basicity: pKa 1.7 for the 4-hydroxy and pKa 7.9 for the 3-piperazine nitrogen [Merck Index]

Stability: Very stable in DMSO; rather stable in water [Merck Index].

Melting point: 183ºC [DrugBank]

Formulation and optimal human dosage: 300 mg tablets (Mycobution, Upjohn). Dose 10 mg/kg, in a single daily administration, not to exceed 600 mg/day, oral or i.v.

Rifampin is also available as part of fixed-dose combinations with other TB drugs such as isoniazid and pyrazinamide (Rifater^® is an example).