Tuberculosis and Isoniazid Acetylation: What A Clinician Needs to Know

Isoniazid (INH) acetylating status and its variability among different regions and parts of the world are well known; however, they are never elaborated much in day-to-day tuberculosis (TB) guidelines. Hence, we discuss three cases of pulmonary TB presenting with drug-induced hepatitis. Workup and evaluation demonstrated slow acetylation of INH, which caused drug-induced hepatitis. The clinical adverse event resolved by transiently stopping anti-TB therapy (ATT) to normalize liver function tests. Following reintroduction of ATT, INH was replaced with levofloxacin in the regimen, taking care to ensure sensitivity to levofloxacin, as an individualized decision-making under expert supervision. We highlight the role of INH acetylating status as a major cause for the same and its management as needed for the treating clinician.