The influence of diuretics on the excretion and metabolism of doping agents--V. Dimefline.

A sensitive method for the quantitative determination of the respiratory stimulant dimefline in 5 ml urine using capillary gas chromatography with nitrogen specific detection is presented. After the oral administration of a therapeutical amount of 16 mg dimefline to five subjects only 0.26 +/- 0.16% of the dose is excreted as the conjugated drug in 24 h. The maximum excretion rate occurred 3 h after dosing, the peak concentration being 154 +/- 60 ng ml-1. The influence of diuretics taken 2 h after the administration of dimefline was studied in three subjects. From these results it appeared that the use of acetazolamide and hydrochlorthiazide in order to circumvent a positive dimefline doping case is questionable. Due to the potent diuretic effect of furosemide, the intake of this diuretic could result in a suppression of the dimefline concentration below the detection limit of 10 ng ml-1.