[Value of determining plasma INH during antitubercular treatment. Retrospective analysis of 204 cases].

Abstract

The acetylator phenotype of 204 tuberculous patients was assessed (152 men and 52 women aged between 15 and 90). The INH dose was adjusted according to Vivien's protocol, measuring the index of inactivation of Isoniazid I3, three hours after the oral dose. In fixing the transition zone of I3 at 0.50 the distribution between slow and rapid acetylators was 53% and 47% respectively. There was no difference for sex, age or ethnic group. The dosage used according to this protocol varied greatly, going from 1.64 mg/kg/day to 13.3 mg/kg/day with a mean value of 2.74 mg/kg/day for slow acetylators and 6.13 mg/kg/day for rapid acetylators. The usual dose advised is 5 mg/kg/day, which may lead equally to over or under treatment though the former is more likely in our experience. Adjusting the dosage is an important feature in good tolerance of the treatment: indeed only 4 of 86 subjects whose dosage has been adjusted showed elevated transaminases, whereas 34 of 118 patients had raised transaminases in the control group on a standard dose before the adjusted treatment was introduced. The difference was significant between the two groups.