Classification of children as slow or rapid acetylators based on concentrations of isoniazid in saliva folowing oral administration of body-weight and surface-area-related dosages of the drug
The acetylator phenotype of 180 children aged
3-11 years was determined on the basis of isoniazid
concentrations in saliva collected at 5 hours after
oral administration of body-weight and surfacearea-
related &sages of the drug in a syrup form.
isoniazid 25 mglkg was administered on one occasion
and 75 mg/m2 surface-area on another, with
an interval of 3 days between the occasions. A
cross-over design was employed and the sequence
was determined by random allocation. The distribution
of the concentrations was bimodal with
both procedures, indicating the presence of two
groups namely, the slow and rapid acetylators. The
criterion for a rapid acetylator was a concentration
of 0.3 μg/ml or less by body-weight-related dosage
and 0.4 μg/ml or less by that based on surface-area.
Based on these criteria, 62 % of the children were
classified as slow acetylators and 38% as rapid
acetylators by body-weight, and 59 and 41 %,
respectively by surface-area, and the findings were
similar in children in the different age-groups. The
agreement between the two procedures was 98%