Tasks of clinical pharmacology in the early phase of drug development

The path of a new drug from the idea to the product may be divided into 2 p hases, namely drug discovery and drug development. Due to the scientific progress new and simple methods could be developed to determine the biological efficacy of a large number of compounds. During t he first part of drug development necessary requirements for the first use in man are met by performing preclinical pharmacological, toxicological and pharmacokinetic investigations in the animal and in in-vitro testing. Afte r a first clinical-pharmacological profile of the new substance has been es tablished during phase I on the basis of which a decision for the continuat ion of the clinical trial is made, the aim of phases II and III is now to a nswer the important questions of the therapeutic efficacy and tolerability in a large number of patients with the target indication. Due to the continuously increasing time and costs of drug development, drug development should be streamlined combining preclinical and early clinical phases as an exploratory stage and later clinical development as a confirm atory stage. The development and appropriate use of surrogates and models may be helpful to determine drug actions in human and to assist in dose selection as the main requirement for a successful large clinical trial in the confirmatory stage. Identifying the genes responsible for the huge variations in how dif ferent patients respond to a drug, in terms of both the product's effective ness and its side effects, and genotyping patients before including in larg e clinical trials may prevent selecting the wrong patient population and av oid expensive repetition of the studies. Taking responsibility as the link between research and development gives cl inical pharmacology a major opportunity to assume a pivotal role in drug de velopment. To reach this goal, clinical pharmacology must be fully integrat ed in the whole process of drug development from the candidate selection un til the approval.