Effects of the chrysotherapeutic agents auranofin and gold sodium thiomalate on hepatic and renal drug metabolism and heme metabolism.

These studies were designed to investigate the effects of the chrysotherapeutic agents auranofin and myochrysine (GST) on hepatic and renal drug-metabolizing enzymes and heme metabolism. Male Sprague-Dawley rats were either administered a single dose of auranofin (17, 34, or 68 mg/kg, p.o.) or administered daily doses of auranofin (0.2, 0.6, 2, 9, or 40 mg/kg/day, p.o.) or GST (1.2 or 5.8 mg/kg/day, i.p.) for 3 or 14 days. Rats were killed 24 h after the final treatment, and subcellular fractions of liver and kidney were prepared. Cytochrome P-450 (P-450) content and ethoxycoumarin-O-deethylase (ECOD), benzphetamine-N-demethylase (BPND), delta-aminolevulinic acid (ALA) synthetase, and heme oxygenase activities were determined. Twenty-four hours following single doses of auranofin, no effects on hepatic P-450, ECOD, or BPND were observed. Treatment with the positive control compounds, CoCl2 (60 mg/kg) and Co-protophorphyrin IX (33 mg/kg), produced decreases in all three variables at 24 hr. Auranofin, at 2 mg/kg, and GST treatment, at both doses, reduced hepatic P-450 and ECOD activity at 3 days. This effect was reversed with continued treatment for 14 days. BPND activity was unaffected at 3 days but was decreased at 14 days. Heme oxygenase activity was enhanced at 3 days and had returned to control activity at 14 days, while ALA synthetase was unaffected. With the exception of heme oxygenase, which was increased, renal variables were unaltered at 3 days. At 14 days, renal P-450 content was decreased in the high-dose auranofin group, heme oxygenase activity was increased in all groups, and ALA synthetase activity was elevated in high-dose auranofin animals. These data indicate that, at doses twenty times the human dose, auranofin and GST administration produced reversible decreases in hepatic and renal P-450 which may be the result of altered heme metabolism.