Enhanced drug metabolism after sulfinpyrazone treatment in patients aged 50 to 60 years.

The induction of liver drug metabolism was investigated in five patients before and after the administration of 800 mg sulfinpyrazone daily for 4 weeks, by using antipyrine plasma-pharmacokinetics and by determining urinary excretion of 6-beta-OH-cortisol and serum gamma-glutamyl-transpeptidase (GGT) activity. Antipyrine half-life was shortened in all patients from a mean value of 12.3 +/- 3.9 h to 7.8 +/- 2.0 h and antipyrine clearance was increased from 39.0 +/- 16.0 ml/min to 57.6 +/- 13.7 ml/min. In contrast the volume of distribution of antipyrine was unaffected; the values being 38.0 +/- 8.6 liters and 37.4 +/- 5.7 liters, respectively. In all patients the excretion of 6-beta-OH-cortisol in the urine went up from 65.0 +/- 25.7 micrograms/24 h to 346.8 +/- 193.4 micrograms/24 h. The ratio 6-beta-OH-cortisol/free cortisol changed from 4.1 to 15.8. After 21 days of treatment the GGT increased from 17.4 +/- 4.9 units/liter to 32.6 +/- 12.5 units/liter The data presented confirm that sulfinpyrazone induces drug metabolism in patients of the older age group. Interactions between sulfinpyrazone and other drugs given simultaneously must be borne in mind.