In Vitro Distribution of Gold in Serum Proteins after Incubation of Sodium Aurothiomalate and Auranofin with Human Blood and its Pharmacological Significance Mohammad S. Iqbal & Syed G. Taqi & Muhammad Arif & Muhammad Wasim & Muhammad Sher Received: 22 January 2009 / Accepted: 23 January 2009 # Humana Press Inc. 2009 Abstract This study presents a comparative drug–protein, in vitro, binding profile of sodium aurothiomalate and auranofin. It was found that about 40% of total protein-bound gold is attached to albumin after incubation of aurothiomalate with whole blood for 24 h and about 29% of it was with α 1 -globulin and the least amount was found with γ-globulin (6.1%). On the other hand, approximately 84% of the protein-bound auranofin gold attached to globulins of which 51% was found with β-globulin band. It was almost equally distributed among albumin, α 2 -globulin and γ-globulin, and showed least affinity for α 1 -globulin. The gold analyses were performed by standardless instrumental neutron activation method duly validated by use of an established atomic absorption method. The results of this study explain to some extent the difference in, in vivo, pharmacokinetics and pharmacodynamics of the two drugs. Keywords Chrysotherapy . Myocricin® . Auranofin . Electrophoresis . Serum proteins . Neutron activation analysis Introduction Gold compounds have been in use for treatment of rheumatoid arthritis for about 70 years but several questions relating to efficacy and toxicity still remain unanswered. The two Biol Trace Elem Res DOI 10.1007/s12011-009-8330-0 M. S. Iqbal (*) Department of Chemistry, GC University, Lahore 54000, Pakistan e-mail: saeediq50@hotmail.com S. G. Taqi Department of Chemistry, University of Sargodha, Sargodha, Pakistan M. Arif : M. Wasim Chemistry Division, Pakistan Institute of Nuclear Science and Technology, PO Nilore, Islamabad, Pakistan M. Sher Department of Pharmacy, University of Sargodha, Sargodha, Pakistan