Compositions comprising at least one peptide copper complex and at least one preservative exhibit chemical stability of the peptide copper complex, as well as resistance and/or toxicity to microbial growth, when the preservative is selected to be a non-formaldehyde-donating preservative. In other embodiments, the present invention is directed to such compositions that are formulated for use as pharmaceuticals and cosmetic products, and to medical devices comprising a disclosed composition. In another aspect, the present invention is also directed to a method for imparting to a composition comprising at least one peptide copper complex, chemical stability as well as resistance and/or toxicity to microbial growth, where the method comprises incorporating a non-formaldehyde-donating preservative in the composition.