A single sample saliva test to determine acetylator phenotype.

A comparison was made between the results of acetylator phenotyping by determination of the acetylisoniazid to isoniazid (AcINH/INH) concentration ratio in plasma and in saliva 3 h after oral administration of isoniazid (200mg). In the 154 subjects studied, 68 (44%) were fast acetylators (AcINH/INH ratio > 1.5) using the plasma ratio. In all subjects the saliva AcINH/INH ratio was also > 1.5. Eighty-five of the eighty-six remaining subjects had saliva and plasma AcINH/INH ratios < 1.5 in the 3 h sample. Thus, with one exception there was complete agreement between the acetylator status determined by measurement of saliva or plasma AcINH/INH ratio in a single 3 h sample. Saliva measurement may provide a simple non-invasive alternative to plasma collection in assessing acetylator status.