Gold excretion and retention during auranofin treatment: a preliminary report

Auranofin, an oral gold compound, was administered to 12 patients with rheumatoid arthritis using 2 dosage schedules (3 mg or 1 mg twice daily for 8 weeks, and then once daily for 18 weeks). In addition to outpatient clinic monitoring, all patients were admitted to a metabolic ward for 3 days for collection of 24 hr daily urine and feces. Gold content of excreta was determined by atomic absorption spectroscopy. Seventy-three per cent of the administered gold was recovered in the urine and feces of patients receiving 3 mg b.i.d., and all the gold was recovered in those taking 1 mg b.i.d. Ninety-five per cent of the recovered gold was in the feces and 5% was in the urine. These findings contrast with those observed during intramuscular (gold sodium thiomalate) chrysotherapy: 40% of the injected dose was recovered, 70% in urine, 30% in feces. Less tissue gold retention occurred with oral gold than with parenteral therapy. Following 20 weeks of auranofin (6 mg/day) chrysotherapy approximately 66 mg of gold was retained. By comparison, 300 mg of gold was retained after injectable gold sodium thiomalate treatment. The significance of these findings is discussed.