Manipulation & Adjustment of the Independent Variable

Research using human subjects is an essential last step in testing the efficacy and ascertaining the potential side effects of new treatments in the mental health field. What methods do researchers use to ensure that care is being taken to protect the physical and psychological well-being of research participants? If you were assigned to test a new drug, Psychocillan, which is designed to treat a new psychological disorder with symptoms that include the inability to pay attention in psychology class, how would you design the research to (a) figure out the efficacy of the drug (i.e. does it work?), (b) determine if there are adverse side effects and if the benefits outweigh those side effects, and (c) determine the population and sample of the study?