Pyrafat is an important sterilizing drug that shortens tuberculosis (TB) therapy. However, the mechanism of action of pyrazinamide is poorly understood because of its unusual properties. In literature it has been written that the pyrazinoic acid (POA), the active moiety of pyrazinamide, disrupted membrane energetics and inhibited membrane transport function at acid pH in Mycobacterium tuberculosis. The antimycobacterial activity appears to partly depend on conversion of the drug to POA. Susceptible strains of M. tuberculosis produce pyrazinamidase, an enzyme that deaminates pyrazinamide to POA, and the vitro susceptibility of a given strain of the organism appears to correspond to its pyrazinamidase activity. Experimental evidence suggests that pyrazinamide diffuses into M. tuberculosis in a passive manner, is converted into POA by pyrazinamidase, and because of an inefficient efflux system, accumulates in huge amounts in the bacterial cytoplasm. The accumulation of POA lowers the intracellular pH to a suboptimal level that is likely to inactivate a vital target enzyme such as fatty acid synthase.
Pyrafat for patients
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Pyrazinamide has been reported to interfere with ACETEST® and KETOSTIX® urine tests to produce a
pink-brown color. 5