The influence of diuretics on the excretion and metabolism of doping agents. II. Phentermine.

The urinary excretion of phentermine in humans was followed over a period of several days after the oral administration of two formulations. The intake of phentermine in a capsule generally resulted in an excretion peak 4 h after the administration followed by a second peak 12 or 24 h post dosing. The total amount excreted during 72 h varied from 62.7 to 84.8%. Concerning the administration of Ionamine 15, a sustained release formulation, the maximal excretion rate was spread over 3-9 h, while more than 85% of phentermine were excreted after 72 h. The excretion was affected by urinary pH. The intake of acetazolamide shortly after phentermine resulted in a decrease of the phentermine excretion during one day and in one subject in a suppression below the detection limit 4 h post dosing. The administration of furosemide or bumetanide produced only a diluting effect during 2 h.