Pharmacodynamics of ¹⁹⁷Au and ¹⁹⁵Au labeled aurothiomalate in blood. Correlation with course of rheumatoid arthritis, gold toxicity and gold excretion

Abstract

Abstract The relationships between serum stable gold ( 197 Au) concentration and serum and whole blood radioactive gold ( 195 Au) disappearance curves to clinical course and gold excretion are analyzed in this prospective clinical‐metabolic study of 18 patients with active rheumatoid arthritis (RA). Patients received a standard course of Myochrysine ( 197 Au aurothiomalate), were given 195 Au labeled aurothiomalate to monitor current dose dynamics, and clinically evaluated at regular intervals. Stable and radiogold concentrations in blood were measured serially on an outpatient basis and during periods of hospitalization using neutron activation anallysis and standard radiometric techniques. Serum concentrations of both isotopes failed to correlate with clinical course and toxicity. Serum radiogold disappearance curves were similar in patients who received radioactive gold on two or more occasions, despite changes in clinical course. Whole blood radiogold disappearance curves however were significantly different in most and least improved patients. These findings, and others reported herein, suggest that a) the probable interstitial or intracellular mechanism(s) of action of gold on the inflammatory process are not dependent upon serum gold concentrations and b) they raise the possibility that whole blood radiogold disappearance curves would provide a means of selecting those patients who will derive maximum therapeutic benefit from chrysotherapy.