Relevance of Isoniazid Dosage in Adults Treated for Tuberculosis

Tuberculosis is the third leading infectious killer. In 2021, an estimated 10,6 million people fell ill with tuberculosis worldwide. Drug resistance emerges with the increase of antibiotherapy use. Among the four antimicrobial drugs used for tuberculosis, isoniazid is a first line treatment. It has a bactericidal activity against the tuberculosis complex. Nevertheless, the hepatic metabolism of isoniazid shows variation between individuals. There is a real risk of hepatotoxicity and neurotoxicity induced by isoniazid. The peak measurement (Cmax) of serum isoniazid is recommended to adjust the treatment and to allow recovery. Moreover, several samples allow a kinetics of isoniazid elimination so as to distinguish slow and fast acetylators. Few data are available on isoniazid acetylation. It could be useful to know the proportion of patients treated by isoniazid at a standard dose, associated with a risk of overdosing or underdosing. Inadequate exposures should be studied to understand if there is an impact in the medical care.