Explaining drug development<< Back to Drug research and development
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The process of drug discovery begins with biomedical research into the pathophysiology of a particular disease with an aim to translate this research into the development of a clinical therapy. This process can take between 10–15 years and is outlined below.
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- Drug target identification
- Preclinical research
- Phase I clinical trials
- Phase II clinical trials
- Phase III clinical trials
- Regulatory review (and approval)
- Phase IV
Drug target identification
This is the identification of a potential therapeutic drug target, including understanding its role in the disease process. In CF, discovery of the CFTR gene enabled researchers to have a better understanding of the pathophysiologic processes underlying the disease, thereby accelerating the development of targeted therapies.
After a candidate drug is identified, in vitro and animal studies are performed to evaluate the pharmacodynamics, pharmacokinetics and toxicology of the pharmaceutical agent. Recommended doses and an accompanying safety profile are generated from this information.
Phase I clinical trials
This is the first stage in testing a novel therapy in humans. These investigations are designed to gather preliminary information on the pharmacokinetics, dosage, safety and tolerability of the drug in about 20 healthy volunteers. Phase I trials are usually performed without a comparison group.
Phase II clinical trials
In phase II trials, the investigational therapy is administered to a relatively larger group of patients (20–400) suffering from the disease. The main objective is to ascertain drug efficacy, with continued evaluation to evaluate safety further. Treatment period per patient is about 1 to 3 months. Occasionally, phase II studies are subdivided into phase IIa, which specifically assess dosing of the therapeutic agent, and phase IIb.
Phase III clinical trials
In phase III trials, the study drug or treatment is given to larger groups of people (1000–3000) to assess its efficacy and any safety signals compared with placebo and commonly used treatments. Most phase III drug trials are designed as randomised, double-blind and placebo-controlled:
- Randomised: Each participant is randomly assigned to receive either the trial treatment or a placebo
- Blind: In a ‘blind study’ the participants are not informed if they are receiving the study drug or a placebo. In a double-blind trial, study investigators are also not informed about who is receiving the trial drug or placebo. ‘Blinding’ is intended to prevent potential biases from either the treating healthcare professional or the participant.
Regulatory review (and approval)
Results of clinical trials along with supporting preclinical and clinical data are collated and submitted to the relevant regulatory authorities to obtain approval to market the drug in their jurisdiction (e.g. a New Drug Application [NDA] in the USA, and a Marketing Authorisation Application [MAA] in the EU).
Once a drug has been approved, the manufacturer must submit marketing authorisation applications in every country or territory where the drug is to be marketed. Phase IV clinical trials are conducted to support these applications and to continue evaluating the drug’s safety and efficacy.