So-called in vitro methods imply laboratory studies of bacterial, animal or human cells. In vitro is latin for: “Within the glass”. The purpose is:

  1. Observe natural processes or manipulate processes within single cells or between cells
  2. Learn about how a component (drug) influence the cells functioning


Often, but not always, it is considered as necessary or useful to test a drug on animals before moving on to trials on humans. Animal trials can be done on small organisms like flies, small animals like mice and rats or bigger animals like pigs. The purpose is:

1) Test safety of a drug in a living organism without risking to harm humans.
2) Measure efficacy and test dosing in a living organism without risking to harm humans 


Testing treatment in humans.

Phase I . These trials test an experimental treatment on a small group of people for the first time. The purpose is:

1) Assess the treatment’s safety
2) Find out what a safe range would be for dosage
3) Identify side effects

Phase II. The treatment is given to a larger group of people to:

1) Obtain preliminary data on the effectiveness of the treatment for a particular disease or condition
2) Further assess the treatment’s safety
3) Determine the best dose

Phase III. The treatment is given to even larger groups of people to:

1) Confirm its effectiveness
2) Monitor side effects
3) Compare it to commonly used treatments
4) Collect information that will allow the treatment to be used safely on the market

Phase IV. Done after the treatment is approved and is on the market. Gather information on things, like the best way to use a treatment, and the long-term benefits and risks