Abstract
Gold salts are important agents in the treatment of rheumatoid arthritis. Determination of the extent to which they bind to plasma proteins at therapeutic concentrations is an essential prerequisite for investigating the role of binding in the pharmacokinetics of these drugs. Few data are available on the binding of aurothiomalate to plasma proteins. Libenson considered that there was no gold free in the plasma. McQueen & Dykes measured the binding of aurothiomalate to rabbit serum proteins and found that the aurothiomalate was bound both to albumin and to the cellulose membrane used for ultrafiltration. Mascarenhas et al. demonstrated that 95% of the gold was bound to the albumin fraction when sodium [195Au] aurothiomalate was incubated with human serum. The authors have now reexamined the binding of the aurothiomalate anion to human plasma proteins and have defined the extent of binding to the cellulose membrane.