KOXIRIP

Ethambutol is bacteriostatic. It is effective against Mycobacterium tuberculosi and M.bovis with an MIC of 0.5–8µg per ml. The exact mechanism of action is unknown. While it has activity against some atypical mycobacteria including M.Kansasii, activity against other micro-organisms has not yet been reported.

Isoniazid is used mainly in the treatment of pulmonary tuberculosis but it appears to be effective also in the treatment of extrapulmonary lesions, including meningitis and genito-urinary disease.

Pyrazinamide exhibits tuberculostatic activity. Pyrazinamide is active only at an acid pH, and it is therefore active mainly on the tubercle bacilli located within the cell.

Rifampicin is an active bactericidial antituberculosis drug which is particularly active against the rapidly growing extracellular organisms and also has bactericidial activity intracellularly. Rifampicin inhibits DNA-dependent RNA polymerase activity in susceptible cells. Specifically, it interacts with bacterial RNA polymerase but does not inhibit the mammalian enzyme.