Rifampicin, also known as rifampin, is an ansamycin antibiotic used to treat several types of bacterial infections, including tuberculosis (TB), Mycobacterium avium complex, leprosy, and Legionnaires' disease.[1] It is almost always used together with other antibiotics with two notable exceptions: when given as a "preferred treatment that is strongly recommended"[2] for latent TB infection; and when used as post-exposure prophylaxis to prevent Haemophilus influenzae type b and meningococcal disease in people who have been exposed to those bacteria. Before treating a person for a long period of time, measurements of liver enzymes and blood counts are recommended.[1] See also Rifampicin.
Rifampicin inhibits bacterial DNA-dependent RNA synthesis by inhibiting bacterial DNA-dependent RNA polymerase.[3] (1i6v).
Crystal structure data and biochemical data suggest that within the DNA/RNA channel, but away from the active site.[4] The inhibitor prevents RNA synthesis by physically blocking elongation, and thus preventing synthesis of host bacterial proteins. By this "steric-occlusion" mechanism, rifampicin blocks synthesis of the second or third phosphodiester bond between the nucleotides in the RNA backbone, preventing elongation of the 5' end of the RNA transcript past more than 2 or 3 nucleotides.[4][5]
In a recent study Rifampicin was shown to bind to cytochrome P450 reductase and alter its conformation as well as activity towards supporting metabolism of progesterone via CYP21A2.[6]
