A small phase IA clinical trial designed to establish whether an
experimental drug is safe for humans to take. Phase I studies
determine the metabolism and pharmacologic actions of drugs in
humans, the side effects associated with increasing doses, and
look for early evidence of effectiveness; these studies may
include either people with HIV, HIV-negative volunteers, or
both/II clinical trialA clinical trial is a research study to
answer specific questions about vaccines or new therapies or new
ways of using known treatments. Clinical trials are used to
determine whether new drugs or treatments are both safe and
effective. Carefully conducted clinical trials are the fastest
and safest way to find treatments that work in people. Trials
are in four phases: Phase I tests a new drug or treatment in a
small group; Phase II expands the study to a larger group of
people; Phase III expands the study to an even larger group of
people; and Phase IV takes place after the drug or treatment has
been licensed and marketed.