What is the role of each drug during intensive phase?
Ans: INH has very high early bactericidal activity (EBA) and acts on rapidly multiplying extra-cellular bacilli. It accounts for 95% kill in bacillary population. Remaining bacilli metabolize slowly and are killed preferentially by Rifampicin . INH is also most effective drug for preventing resistance to other drugs. On the other hand, other drugs are not so efficient in preventing resistance to INH, which is therefore more common. Rifampicin also has high bactericidal activity but starts acting little later. It acts on rapid as well as intermittently (found in caseous lesions) multiplying bacilli. Pyrazinamide acts on intra-cellular bacilli that are particularly inhibited by acid environment inside macrophages. Ethambutol is the companion drug to prevent drug resistance.
Ans: INH has very high early bactericidal activity (EBA) and acts on rapidly multiplying extra-cellular bacilli. It accounts for 95% kill in bacillary population. Remaining bacilli metabolize slowly and are killed preferentially by ‘Rifampicin’. INH is also most effective drug for preventing resistance to other drugs. On the other hand, other drugs are not so efficient in preventing resistance to INH, which is therefore more common. Rifampicin also has high bactericidal activity but starts acting little later. It acts on rapid as well as intermittently (found in caseous lesions) multiplying bacilli. Pyrazinamide acts on intra-cellular bacilli that are particularly inhibited by acid environment inside macrophages. Ethambutol is the companion drug to prevent drug resistance.
