Capreomycin is an antibiotic, which is used in combination other antituberculosis drugs fro the treatment of pulmonary infections caused by capreomycin-susceptible strains of M. tuberculosis when the primary agents (isoniazid, rifampin, ethambutol, aminosalicylic acid, and streptomycin) have been ineffective or cannot be used because of toxicity or the presence of resistant tubercle bacilli. Little is known about capreomycin's exact mechanism of action, but it is thought to inhibit protein synthesis by binding to the 70S ribosomal unit. Capreomycin also binds to components in the bacterial cell which result in the production of abnormal proteins.

Ethionamide is a second-line agent, structurally similar to isoniazid, used as a second-line therapy for the treatment of multidrug-resistant tuberculosis or active tuberculosis in case of patient intolerance to other drugs. Depending on its the concentration at the infected site and the susceptibility of the infecting organism it may be bacteriostatic or bactericidal. When used alone rapidly develops bacterial resistance. Ethionamide was approved by FDA in 1965 as TRECATOR manufactured by Wyeth Pharmaceuticals Inc. (purchased by Pfizer in 2009). Ethionamide is specific for Mycobacteria and is thought to exert a toxic effect on mycolic acid components of the bacterial cell wall when activated through intermediate S-oxidation by EtaA. Mycolic acid synthesis was shown to be inhibited by ethionamide in the EthA protein-overexpressing mycobacteria,

Methaniazide (metaniazide) is the methanesulfonate derivative of isoniazid with antibacterial properties. It is used used primarily as a tuberculostatic. It remains the treatment of choice for tuberculosis.