Although the use of pharmacokinetic/pharmacodynamic modelling and simulatio
n (M&S) in drug development has increased during the last decade, this has
most notably occurred in patient studies using the population approach. The
role of M&S in Phase II although of longer history, does not presently hav
e the same impact on drug development. However, trends such as the increase
d use of biomarkers and clinical trial simulation as well as adoption of th
e learn/confirm concept can be expected to increase the importance of model
ling in Phase I. To help identify the role of M&S, its main advantages and
the obstacles to its rational use. an expert meeting was organised by COST
B15 in Brussels, January 10-11, 2000, This article presents the views expre
ssed at that meeting. Although it is clear that M&S occurs in only a minori
ty of Phase I clinical trials. it is used for a large number of different p
urposes. In particular. M&S is considered valuable in the following situati
ons: censoring because of assay limitation, characterisation of non-lineari
ty, estimating exposure-response relationship. combined analyses, sparse sa
mpling studies, special population studies. integrating PK/PD knowledge for
decision making, simulation of Phase II trials, predicting multiple dose p
rofile from single dose, bridging studies and formulation development. One
or more of the following characteristics of M&S activities are often presen
t and severely impede its successful integration into clinical drug develop
ment: lack of trained personnel, lack of protocol and/or analysis plan, abs
ence of pre-specified objectives, no timelines or budget, low priority, ina
dequate reporting, no quality assurance of the modelling process and no eva
luation of cost-benefit. The early clinical drug development phase is chang
ing and if these implementation aspects can be appropriately addressed, M&S
can fulfill an important role in reshaping the early trials by more effect
ive extraction of information from studies, better integration of knowledge
across studies and more precise predictions of trial outcome, thereby allo
wing more informed decision making. (C) 2001 Elsevier Science B.V. All righ
ts reserved.