Ethionamide is primarily used as an antibiotic in the treatment of tuberculosis, particularly in cases where the disease is resistant to first-line medications like isoniazid and rifampin. It is often prescribed as part of a combination therapy to enhance its effectiveness and reduce the risk of developing further drug resistance. The compound works by inhibiting the synthesis of mycolic acids, which are essential components of the bacterial cell wall, thereby preventing the growth and replication of Mycobacterium tuberculosis. Due to its potential side effects, such as gastrointestinal disturbances and liver toxicity, it is typically administered under close medical supervision. Ethionamide is also sometimes used in the treatment of leprosy, though its use in this context is less common.