Prothionamide is primarily used in the treatment of tuberculosis, particularly in cases where the bacteria have developed resistance to first-line drugs like isoniazid and rifampicin. It is often included in combination therapy to enhance effectiveness and reduce the risk of further resistance. The drug works by inhibiting the synthesis of mycolic acids, which are essential components of the bacterial cell wall, thereby stopping the growth of the Mycobacterium tuberculosis. Prothionamide is also employed in the management of leprosy, especially in multidrug therapy regimens, to target and eliminate the causative agent, Mycobacterium leprae. Its use is carefully monitored due to potential side effects, including gastrointestinal disturbances and liver toxicity, but it remains a valuable option in the fight against these persistent infections.