Ethionamide (2-ethylthioisonicotinamide) is a nicotinamide derivative, with antibacterial activity, used to treat tuberculosis. Although the exact mechanism of action of ethionamide is unknown, it may inhibit the synthesis of mycolic acid, a saturated fatty acid found in the bacterial cell wall, thereby inhibiting bacterial cell wall synthesis. This eventually leads to bacterial cell wall disruption and cell lysis. Ethionamide may be bacteriostatic or bactericidal in action, depending on the concentration of the drug at the site of infection and the susceptibility of the organism involved.

Ethionamide 是Isoniazid（INH）的结构类似物，它们均为前药，需要通过分枝杆菌酶的激活才能发挥抗菌活性。Ethionamide 的作用机制被认为与INH相同，尽管激活途径与INH不同。Ethionamide 通过EthA酶激活，生成具有明显优于原药的S氧化物代谢产物。[1]Ethionamide 抑制生物膜的形成并降低成熟生物膜的存活性。Ethionamide 减少隐球菌属的游离细胞中的麦角固醇含量，并破坏或增加真菌细胞膜的通透性，导致大分子物质泄漏。[2]一般情况下，Ethionamide 在0.50 mM以上浓度对HepG2、Caco-2和RAW巨噬细胞具有毒性，但当Ethionamide 载入微粒中时，毒性大大降低。Ethionamide 在热碳化多孔硅（TCPSi）颗粒存在下显示快速的代谢过程。[3]Ethionamide 在结核分枝杆菌中通过Rv3854c基因编码的蛋白质被激活。Ethionamide 似乎扰乱细胞壁的生物合成，并至少有一个共同的细胞靶标，即烯酰载体蛋白还原酶InhA。[4]