Metal‐Based Drugs

Abstract

Metallopharmaceuticals have a long history in the development of chemotherapy. The more recent success of cisplatin and six related Pt‐based antitumor drugs, and longer histories of chrysotherapy (gold treatments) for arthritis, bismuth antiulcer agents, and silver‐, antimony‐ and arsenic‐based antimicrobial agents demonstrate that the periodic table represents a potential wealth of medicinal agents to be explored and developed in the future. This article reviews the use of twelve elements (Ag, As, Au, Bi, Ga, Li, Pt, Ru, Sb, Sn, Ti, V) for a wide variety of diseases and disorders. The current state of research on particular applications varies widely – from promising treatments that have not yet reached the clinic to those that are well established empirically despite uncertain mechanisms of action. The array of antitumor agents licensed or in clinical trials includes compounds of As, Ga, Ru, and Ti, in addition to platinum. There are also exciting efforts to apply known treatments or biological properties to new diseases by taking advantage of extensive databases, for example, developing antitumor agents from organotin complexes that have long been used as fungicides and antifouling agents, and antimicrobial agents from gold complexes. The ability to modulate the properties of metal complexes by choice of the oxidation state (Au I vs Au III ; Pt II vs Pt IV ; V III , V IV & V V , etc.) and design of the medical carrier ligands (e.g. 1,2‐diaminocyclohexane vs two ammine ligands for Pt antitumor agents) allows targeting of particular tissues or cells and balancing of lipophilicity, solubility, and reactivity to balance therapeutic activity against toxicity. Many, if not most, metallopharmaceuticals are prodrugs that undergo redox changes and/or ligand exchange reactions in vivo to generate the active species. Hence, research on metallodrug metabolism and pharmacology is as important as the initial medicinal screening of the agents.