Development and safety testing of medicines

  • It requires a great deal of time and money to discover and develop new medicines.
  • The average development time for medicines is twelve years. Within this twelve years there are many different stages that researchers have to go through.

Discovery Research (0-3 yrs)

  • This stage relates to the work of chemists, biologists and pharmacologists. The work involves extracting and synthesising new molecules.
  • For every one medicine on the shelf, thousands are unsuccessful and are never developed.
  • When a useful activity for a molecule is discovered, chemists improve its structure by making any close variations (analogues) which may have a stronger desired effect.

Development Research (0-9 yrs)

  • Work is done in this stage to ensure that the medicine is safe for humans.
  • Scientists work out whether it is safe, stable and how it is likely to be absorbed and excreted by the body.
  • A form that can be given to patients is also developed (e.g. injection, capsule, tablet…).
  • Once this has been completed, clinical studies can begin.

Phase I trials

  • The aim of the phase I trials is to determine whether the medicine is tolerated and behaves in the way predicted by previous experimental investigations.
  • The trials involve administering the drug to healthy volunteers under close observation of a qualified doctor.
  • Original doses will be the lowest that they can be in order to obtain information. The doses are then gradually raised to the expected therapeutic dose level.
  • Sometimes people who have the medical condition that the medication will be used for are tested upon, as the compounds may sometimes be too powerful to test on healthy people (e.g. cancer treatments).
  • The data from the trials is then collected and an application to the UK Medicines Control Agency is made, in order to gain a certificate to conduct clinical trails.
  • The information is reviewed by independent experts who decide whether or not to grant the certificate. If the certificate is granted, clinical trials can begin, if not more information needs to be attained.

Phase II trials

  • These are the first trials in which the illness is actually treated.
  • Different doses are given to different patient groups to establish whether the drug is suitable for further study, or whether it should be abandoned.
  • Patient numbers are usually small.

Phase III trials

  • In this stage, the new medicine is compared with a “dummy” medicine (Placebo Medicine), and maybe a current medicine in use to provide a reference standard.
  • Patients are randomly allocated to one of the groups and neither the doctor nor the patient knows which medicine they are taking.
  • At the end of the trials, a positive result would be indicated by an improvement in the patients who were given the new drug.
  • These trials usually involve a larger group of patients, so that the results can be analysed statistically.
  • If the medicine proves to be successful, a product license application can be made.

Later Stages of Development

  • Only around 10% of compounds making it to Phase I studies survive through to be licensed.
  • The time scales on making new medicines vary substantially, depending upon what the drug is likely to be use for. For example, chronic diseases will take a longer time to test than simple infections.

Useful books for revision

Revise A2 Chemistry for Salters (OCR A Level Chemistry B)
Salters (OCR) Revise A2 Chemistry