Drug discovery

The first step in the drug discovery pipeline is the characterisation of the disease process and identification of drug (‘therapeutic’) targets. Here, a ‘target’ is defined as a protein or messenger RNA which, when modified by a drug, favourably affects the outcome of a disease.

In traditional drug discovery pipelines (Figure 6), less than 10% of candidate targets turn out to be valid after the investment of millions of dollars and six to seven years of work (5). More than 50% of drugs fail at phase II clinical trials due to the lack of efficacy, i.e. the drug is not harmful to humans, binds to the intended target and has drug-like properties (e.g. a reasonable half-life in the human body), but it does not significantly affect the disease.

The drug discovery process — **Figure 6** It is well known that de novo drug discovery and development is a 10-17 year process from idea to marketed drug. The probability of success is lower that 10%. Reprinted by permission from Macmillan Publishers Ltd: Nature Rev. Drug Disc. Ashburn TT and Thor KB. Drug repositioning: identifying and developing new uses for existing drugs. 3: 673-83, copyright 2004 (6 ).

Functional genomics I

Drug discovery

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