If a drug is approved for a Phase II clinical trial the number of participants is increased to 20 – 300 participants.

This phase of clinical testing will determine how well the drug actually works and what the most effective dose is. Phase II also continues to assess the safety of the drugs.

There are sometimes two parts to Phase II trials, phase IIA and phase IIB. In phase IIA the dosing requirement of the drug is assessed. In phase IIB the efficacy of the drug is tested to determine how effective it is as a treatment.

Some phase II trials are designed as a case series that means dosing occurs within a selected group of patients. Other phase II clinical trials are randomized, meaning that different groups of participants chosen at random receive different treatments. The drug being tested is given to one group and either an existing medication or a placebo is given to the second group.

This is done so that researchers can compare the effects of the new drug against existing drugs or no treatment at all. Phase II trials may be the first time that the drug or medication is tested in multiple facilities. The increased number of participants in phase II trials helps to verify the effectiveness of the drug.

As with all clinical trials, phase II trials are closely monitored by sponsors, government agencies and the clinical trials team throughout the process. Protocols are followed and patients are informed about what to expect every step of the way.

Phase II trials may be conducted by a patient’s regular doctor or by members of the clinical trial team. Some phase II clinical trials allow participants to find out the results of the trial. Check with your clinical trial team to see if the results will be made available. If the drug passes phase II testing, then it will progress to phase III clinical trials.