THE PLACEBO-EFFECT IN HEALTHY-VOLUNTEERS - INFLUENCE OF EXPERIMENTAL CONDITIONS ON THE ADVERSE EVENTS PROFILE DURING PHASE-I STUDIES

In contrast to the plethora of publications on placebo effects in pati ents, very tittle is known about placebo effects in healthy volunteers during clinical pharmacology studies. We therefore reviewed the adver se events spontaneously reported during placebo administration in 109 double-blind, placebo-controlled studies involving 1228 volunteers. Th e overall incidence of adverse events in the healthy volunteers during placebo administration was 19%. As expected, complaints were more fre quent after repeated dosing (28%) and in elderly subjects (26%). Overa ll, the most frequent adverse events were headache (7%), drowsiness (5 %), and asthenia (4%), with some variation depending on study design a nd population. In conclusion, these data shed new light on the impact of experimental conditions on the results of safety evaluations in hea lthy volunteers participating in clinical pharmacology studies.