A method for the systematic and efficient synthetic preparation and identification of metabolites of a pharmaceutical product in order to study possible toxic and/or otherwise biologically-active metabolites of such pharmaceutical products as early and conveniently as possible in the very expensive drug development process, comprising adding samples of the pharmaceutical product to a series of combinations of a synthetic metalloporphyrin (SMP) with a synthetic metalloporphyrin-co-oxidizing reagent in the presence of a suitable solvent, under specified conditions, in a manner such that each sample of pharmaceutical product is reacted with a different combination of synthetic metalloporphyrin, SMP-co-oxidizing reagent and solvent, followed by separation and isolation of the resulting oxidative products, then confirmation of the identity of metabolites from the pre-identified oxidative products by appropriate animal model studies, and subjecting the actual metabolites prepared in larger quantities by the above method to toxicologic, pathologic, histopathologic, mechanistic or genotoxic testing in order to identify toxic and/or otherwise metabolically-active beneficial or detrimental individual metabolites.