Introduction
Drug development is a long process, commonly taking 12-15 years from discovery to the granting of a marketing authorisation (formerly known as 'licensing'). Estimates vary, but the overall cost of bringing a new medicine to market is £200-800 million. When the cost of failed discovery efforts are taken into account, these estimates rise to over £1 billion. Despite the huge investment, the amount of information about a new drug that is available at launch is limited. It may take a further 10 years to determine the drug's optimal clinical role.
The preclinical phase involves the study of candidate molecules in cells, isolated tissues and animal models. Drugs that appear to have promise then enter clinical drug development, which can be divided into two parts often referred to as the early 'learning' phase and a later 'large scale 'confirming' phase. Traditionally these have each been subdivided to create four phases of drug development (Fig 6).
The traditional drug development process
Fig 6 The stages and phases of drug development.
PK = pharmacokinetics, PD = pharmacodynamics.
