Determination of acetylator phenotype in Caucasians with caffeine.

Acetylator status in 595 healthy Caucasian volunteers was determined with caffeine. The test group consisted of 372 males and 223 females, 18 to 78 years of age. 312 volunteers were smokers. Caffeine was taken orally as Coffein Comprette (200 mg caffeine x H2O) and urine was collected for 8 h. The metabolic ratio (MR) of 5-acetylamino-6-formylamino-1-methyluracil (AFMU) to 1-methylxanthine (MX) was determined by HPLC. In total 61.7% of the group had a MR less than 0.48 and were classified as slow acetylators. MR varied from 0.01 to 0.47 in the slow acetylators and from 0.48 to 4.7 in the fast acetylator group. Clear dependence of acetylator type upon age, sex or smoking behaviour was not observed. The present study has confirmed the caffeine test as a feasible tool to determine acetylation capacity.