Pyrazinamide kills or stops the growth of certain bacteria that cause tuberculosis (TB). It is used with other drugs to treat tuberculosis. It is a highly specific agent and is active only against Mycobacterium tuberculosis. In vitro and in vivo, the drug is active only at a slightly acid pH. Pyrazinamie gets activated to Pyrazinoic acid in the bacilli where it interferes with fatty acid synthase FAS I. This interferes with the bacteriums ability to synthesize new fatty acids, required for growth and replication.