Toxicological aspects of topical silver pharmaceuticals

Silver is generally considered to present a relatively low toxic threat to humans because unintentional exposure to large doses of the noble metal is quite rare. However, as the intentional utilization of silver in pharmaceutical preparations and devices increases, subtle toxic effects of silver may be predictable and expected. The present review examines the scientific literature, primarily covering the past 10 years, dealing with reports describing various types of silver toxicity. These reports consist of both in vitro and in vivo data dealing with immunological, mesenchymal, neural, and parenchymal cell types. Particular emphasis is given to (1) the use of silver in topical antimicrobial preparations as toxicity relates to absorption through dermal wounds into the systemic circulation and possible effects on delayed wound healing, (2) possible local silver toxicity via iontophoretic devices, (3) current theories relating to the toxicological mechanism of action of silver.