<Li> Phase IIB studies look to find the optimum dose at which the drug shows biological activity with minimal side - effects (' definite dose - finding' studies). </Li> <P> Some trials combine Phase I and Phase II, and test both efficacy and toxicity . </P> <Dl> <Dt> Trial design </Dt> <Dd> Some Phase II trials are designed as case series, demonstrating a drug's safety and activity in a selected group of patients . Other Phase II trials are designed as randomized controlled trials, where some patients receive the drug / device and others receive placebo / standard treatment . Randomized Phase II trials have far fewer patients than randomized Phase III trials . </Dd> </Dl> <Dd> Some Phase II trials are designed as case series, demonstrating a drug's safety and activity in a selected group of patients . Other Phase II trials are designed as randomized controlled trials, where some patients receive the drug / device and others receive placebo / standard treatment . Randomized Phase II trials have far fewer patients than randomized Phase III trials . </Dd>

The fda requires phases of testing in humans