Mechanism of action of rifampicin?

Ans. b (DNA dependent RNA polymerase inhibition) (Ref. KDT 6th/pg. 471)RIFAMPICIN - Mechanism of Action has both intracellular and extracellular bactericidal activity. It blocks RNA synthesis by specifically binding and inhibiting DNA-dependent RNA polymerase.0RIFAMPICINIntroduction# Rifampin is a semisynthetic derivative of Streptomyces mediterranei.# It is considered the most important and potent antituberculous agent.# It is also active against a wide spectrum of other organisms, including some gram-positive and gram-negative bacteria, Legionella spp., M. kansasii, and M. marinum.Pharmacology# Rifampin is a fat-soluble complex macrocyclic antibiotic that is absorbed readily after either oral or intravenous administration.# Serum levels of 10 to 20 pg/mL follow a standard adult oral dose of 600 mg.# Rifampin distributes well throughout most body tissues, including inflamed meninges.# The fact that rifampin turns body fluids (urine, saliva, sputum, tears) a red-orange color makes it simple and inexpensive to check on patients' compliance with therapy.0# Rifampin is excreted primarily through the bile and the enterohepatic circulation, while 30 to 40% of a dose is excreted via the kidneys. 0# The drug is administered either twice weekly or daily at a dose of 600 mg for adults (10 mg/kg) and 10 to 20 mg/kg for children.Adverse Effects# The most common adverse event is gastrointestinal upset.# Hepatitis.# Rash (0.8%), -Hemolytic anemia (<1%), -Thrombocytopenia, and -Immunosuppression of unknown importance.# Rifampin is a potent inducer of the hepatic microsomal enzymes and thereby decreases the half-life of a number of drugs, including digoxin, warfarin, prednisone, cyclosporine, methadone, oral contraceptives, clarithromycin, the HIV protease inhibitors, the HIV nonnucleoside reverse transcriptase inhibitors, and quinidine.The dose of rifampin generally does not require reduction in patients with renal failure0MOC of some Anti-bacterial agentsAntibacterialSite of actionMechanism of actionVancomycinCell wallInterferes with addition of new cell-wall subunits (muramyl pentapeptides)BacitracinCell wallPrevents addition of cell wall subunits by inhibiting recycling of membrane lipid carrierMacrolides (erythromycin)Protein synthesisBind to 50S ribosomal subunitLinosamides (clinda)Protein synthesisBind to 50S ribosomal subunitChloramphenicolProtein synthesisBind to S0S ribosomal subunitTetracyclineProtein synthesisBind to 30S ribosomal subunitAminoglycosides (genta)Protein synthesisBind to 30S ribosomal subunitMupirocinProtein synthesisInhibit isoleucine tRNA synthetase