- Mutagenic potential — effects on genetic stability of bacteria (Ames test) of mammalian
cells in culture - Carcinogenic potential — required if drug is to be administered for prolonged periods
of time - Reproductive performance effects — effects on animal progeny, production of birth
defects
Once a molecule successfully passes the preclinical testing, it is ready for human clin-
ical trials. There are four phases of human clinical trial.
Phase 1 — the effects of the drug as a function of dose are measured in a small
number (25–45) of healthy volunteers who do not have the disease under study;
safety is primarily evaluated.
Phase 2 — the drug is studied in a small number of people (20–150) who have the
disease under study; both safety and efficacy are evaluated.160 MEDICINAL CHEMISTRY
Figure 3.10 The drug development process. The timeline for drug discovery and development is
long, adding to the high cost of drug development. Computational methods have helped to
shorten this timeline.