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Some types of clinical trials:

  • Disease prevention — using drugs, vitamins, foods to reduce risk
  • Treatments — new drugs or combinations of drugs; new ways of giving treatment, new types of treatment
  • Diagnosing disease — new tests or scans
  • Controlling symptoms — new drugs or complementary therapies

Trials aim to find out if a new experimental drug or procedure

  • Is safe
  • Has side effects
  • Works better than the currently used treatment
  • Helps you feel better

New treatments must be thoroughly tested. A new drug, for example is investigated first in the laboratory. If it looks promising, it is carefully studied in people. There are three different types of clinical trials. These are called Phase 1, 2 and 3.

Phase 1 is the earliest trials in the life of a new drug or treatment. They are usually small trials, recruiting up to 30 patients.

About 70% of new treatments tested at Phase 1 make it to Phase 2 trials. Phase 2 trials are often larger than Phase 1. There may be up to 50 people taking part. If the results of Phase 2 trials show that a new treatment may be as good or better than existing treatment, it then moves to Phase 3.

Phase 3 trials compare new treatments with the best currently available treatment (the standard treatment). Phase 3 trials are usually much larger than Phase 1 or 2. This is because differences in success rates may be small, so many results are required to show the difference. Sometimes Phase 3 trials involve thousands of patients in many different hospitals and even different countries. Phase 3 trials are usually randomized. This means the researchers put the people taking part into two groups at random. One group gets the new treatment and the other the standard treatment.