Pyrithyldione excretion in the urine. Methods and results from various collectives

: A simple thinlayer chromatographic method for the detection of pyrithyldion in 5 ml of urine per analysis is described. Sensitivity (0.01 mug of pyrithyldion) and specificity (reaction still positive 5-6 days after injection of 50 mg of pyrithyldion) of the method are considered acceptable. The duration of elimination for pyrithyldion is relatively long (5-6 days). Epidemiological investigations were conducted in two different patient groups to analyze spontaneously voided urine samples. The incidence of positive urine samples in 204 ambulatory internal medicine patients was only 0.5% for pyrithyldion and N-acetyl-p-amino-phenol (the main metabolite of phenacetin). In contrast, the incidence in a specially selected group of 600 working women with regular intake of analgesics was much higher (between 17.7% and 28%) in the period 1969 to 1972.