Interindividual variability of coumarin 7-hydroxylation in a Turkish population

Eur J Clin Pharmacol. 1994;47(4):315-8. doi: 10.1007/BF00191161.


One hundred healthy Turkish volunteers (70 male, 30 female) aged from 19 to 56 years were given 5 mg coumarin p.o. after an overnight fast. Urine samples were collected before and 2, 4 and 8 h after drug administration. The extent and rate of formation of 7-OH-coumarin (7OHC) was determined by the urinary excretion of the metabolite as measured with the fluorometric method. On average, 80% of 7OHC formed was excreted in 2 h. The total amount of 7OHC formed was 59.8% (21.5%) (mean and SD, n = 100, range 17-100%) of the given dose. The percentage of 7OHC excreted during the first 2 h compared with the 7OHC excretion at 8 h was a constant and stable individual characteristic for the rate of the formation of 7OHC ('2 h coumarin test'). Although four individuals had relatively slow coumarin test values (34-40%), no clear-cut polymorphism in the rate of 7OHC formation was found. However, 7OHC formation was lower in males and in cigarette smokers.

MeSH terms

  • Adult
  • Age Factors
  • Coumarins / metabolism*
  • Female
  • Humans
  • Hydroxylation
  • Individuality*
  • Male
  • Middle Aged
  • Plants, Medicinal
  • Polymorphism, Genetic / genetics*
  • Sex Factors
  • Smoking
  • Turkey


  • Coumarins
  • coumarin