Preclinical testing for teratogenicity and developmental toxicity: methods and limitations

With regard to the risk of reproductive or developmental toxicity, the regulatory decisions to allow clinical trials in humans or the marketing of a new drug are based almost entirely on animal data. This is not the case for other types of toxicity for which the preclinical data are supported by data from clinical trials. Whilst animal studies have been remarkably successful in the detection of reproductive toxicology over the last 40 years, they are not infallible. The efficacy of animal experimentation is largely dependent on the selection of appropriate animal models. Progress in the study of teratogenic mechanisms, comparative physiology, developmental biology and pharmacokinetics will hopefully continue to bring about more economical and effective uses of animals. Nevertheless, owing to the limitations of animal models, the monitoring of human births unfortunately remains an essential defence in the detection and early prevention of chemical-induced birth defects.