Hepatotoxicity Associated With Isoniazid Preventive Therapy

Abstract

More than 30 years after its introduction,¹ isoniazid preventive therapy for latent tuberculosis (TB) infection is still a subject of debate, mainly because of continuing concerns about hepatotoxicity.^2-5 There are, however, good reasons to reconsider the hepatotoxicity of isoniazid at this time, with the anticipation that the risk is less than believed. The base of evidence for isoniazid hepatotoxicity, including a level of risk in the range of 5 to 20 cases of hepatotoxicity expected per 1000 persons receiving treatment with a 1% to 10% case-fatality rate, is composed of studies done more than 20 years ago.^6-9 However, the early studies included patients who received a diagnosis of isoniazid hepatotoxicity on the basis of modest elevations of serum transaminase enzymes. Such patients would probably not be classified as having hepatotoxicity in current studies.