The relevance of preclinical studies for the treatment of Parkinson's disease

An essential element of pharmaceutical development, defined as the period between the discovery of a new agent and its market release, is provided by the cc preclinical studies. They consist of the in vitro and in vivo studies performed before examination of the agent in human subjects. Regulatory authorities prescribe specific requirements regarding the nature and number of preclinical studies. In the present paper, we discuss the relevance of these studies for the treatment of Parkinson's disease (PD) on the basis of three examples: the L-DOPA (L-3,4-dihydroxyphenylalanine, levodopa) story; the development of selegiline as a palliative and neuroprotective drug; and the safety concerns regarding tolcapone, an inhibitor of central and peripheral catechol-O-methyltransferase (COMT).