Abstract
Placebo effect is a term that sums up the non-specific effects of a medical intervention or non-pharmacodynamic effects of a drug. The effect is based on patient's expectancy.However, there is an accumulating evidence, that placebo, in spite of being a non-specific drug, has an effect on metabolic, biochemical and electrophysiological activity of the brain.
Placebo is an instrument of clinical drug research, that is indispensable in cases of the absence of an effective treatment for a disorder. It is also needed to confirm true effect of an experimental drug in comparisons with a reference drug, in double dummy designs and as a placebo lead-in period.
There are ethical problems associated with the use of placebo in research as well as in clinical practice. However, some risks associated with placebo may be misjudged.
Effective guidelines have been developed to protect experimental subjects and also to define conditions for justified use of placebo in clinical research.