The clinical phase of drug development should be concluded sooner and
at a lower cost if primarily only the pivotal and supportive studies w
ere to be conducted. Such improved efficiency requires development of
a decision support system that delivers five new capabilities: (i) it
enables one to predict a result of a clinical study and to identify th
ose studies that are expected to have an acceptable probability of suc
cess; (ii) it will allow one to optimally utilize available pharmacoki
netic and pharmacodynamic (PK/PD) data and improve its predictive capa
bility as more data become available; (iii) it will enable one to proj
ect useful population results, not just mean results; (iv) predictions
will be accompanied by a measure of reliability; and (v) expected ini
tial clinical results will be predictable from animal and related drug
class data. With such a tool population targets could be specified ve
ry early in the drug development programme, challenged, and then ratio
nally revised at each step during the development process. This report
describes progress in developing and testing a clinical trials Foreca
ster, a prototype for such a system. The Forecaster generates estimate
s of the joint density for a population of combined PK/PD parameters.
That population then serves as a surrogate for the population of indiv
iduals. When the resulting joint density is sampled, the obtained sets
of parameters may be used to generate data that is statistically indi
stinguishable from the original experimental data. Such simulated data
can be used to validate assumptions, and make inferences on specified
population targets that are accompanied by a measure of prediction re
liability. We demonstrate use of the forecaster by employing N = 22 PK
/PD parameter sets for an orally administered analgesic. (C) 1998 John
Wiley & Sons, Ltd.