Drug development observational studies

This section deals with the question of whether there are quantitatively detectable and interpretable correlations between the dose of an administered drug, or the concentration of a drug and its metabolites measured in the blood or plasma (blood or plasma level), and the therapeutic action or side effects observed. Investigations relating to questions of this type are called PK PD (pharmacokinetic pharmacodynamic) studies. The PK PD analysis is a bidirectional approach pharmacokinetics represent what the body does with a drug, and pharmacodynamics describes what a drug does to the body. The PK PD analyses are key elements of early drug development, and PK PD trials are able to answer specific disease-related efficacy and safety questions. 

The observed CEPH population mean IC50 for both docetaxel and 5-fluorouracil was similar to IC50 values observed across the NCI60 panel of human tumor cell lines (http //dtp.nci.nih.gov) (17). In addition, docetaxel- and 5-fluorouracil-induced cell death is mediated by caspase-3 cleavage, similar to that observed in tumor cells (17). These data are encouraging for the use of CEPH pedigrees as a discovery tool. However, the ultimate proof of the value of the cell-based models will be the human validation of markers derived from this process. These studies he ahead and will help position cell-based models in their correct place in the drug development process. 

This is the first time a data base.of this size and degree of comprehensiveness has been compiled on the state of new drug development in any country. We are currently obtaining further information on investigational NCEs, which will include the reasons for termination of clinical research by the firms and full data on licensed compounds. These additional data will clarify some of the trends that have been revealed by the present study, and will allow further analyses to be performed of the reasons behind the observed changes. 

A wide popularization of the social use of MDMA occurred in 1984-1985 and, with the reported observation of serotonin nerve changes in animal models resulting from the administration of the structurally similar drug MDA, an administrative move was launched to place it under legal control. The placement of MDMA into the most restrictive category of the Federal Controlled Substances Act has effectively removed it from the area of clinical experimentation and human research. The medical potential of this material will probably have to be developed through studies overseas. 

Tolerance, dependence, and withdrawal indicators have been observed in a number of studies. Users who are fond of its escapist qualities say it has a high potential for psychological dependence and that tolerance to the drug develops fairly quickly. 

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