Stimulant and relaxant drugs combined with stimulant and relaxant information: a study of active placebo.
BACKGROUND
The active placebo hypothesis states that placebo effects are potentiated when an active drug is administered.


OBJECTIVE
This hypothesis was tested in an experiment where information about the effect of a drug was combined with administration of an active drug or placebo.


METHODS
Information that a drug acted as a relaxant, a stimulant, or as a placebo was crossed with oral administration of a relaxant drug (700 mg carisoprodol), a stimulant drug (400 mg caffeine) or placebo (lactose) in healthy volunteers ( n=94). Dependent variables were subjective and physiological measures of arousal, as well as serum carisoprodol and caffeine levels. Data were collected from 15 to 280 min after administration of drug or placebo.


RESULTS
Caffeine increased alertness, systolic and diastolic blood pressure, startle blink reflexes, and skin conductance responses. Subjects were calmer after carisoprodol, and heart rate was increased. There was a positive correlation between increased arousal and carisoprodol levels when stimulant information had been provided. However, this was only seen when carisoprodol levels were very low. There was no evidence that caffeine modulated the placebo response.


CONCLUSIONS
Active placebo responses were seen only transiently when carisoprodol levels were low, and only in the subjective arousal data. Caffeine did not support active placebo responses. The overall findings did not favour the active placebo hypothesis.
Flaten
Magne Arve
MA
Department of Psychology, University of Tromsø, Breivika, 9037 Tromsø, Norway. magnef@psyk.uit.no
Simonsen
Terje
T
Zahlsen
Kolbjørn
K
Aamo
Trond
T
Sager
Georg
G
Olsen
Harald
H
D000328:Adult; D001143:Arousal / Q000187:drug effects; D001767:Blinking / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects; D002110:Caffeine / Q000097:blood / Q000494:pharmacology; D002328:Carisoprodol / Q000097:blood / Q000494:pharmacology; D002395:Catecholamines / Q000097:blood; D000697:Central Nervous System Stimulants / Q000097:blood / Q000494:pharmacology*; D002851:Chromatography, High Pressure Liquid; D004305:Dose-Response Relationship, Drug; D004576:Electromyography; D005260:Female; D005712:Galvanic Skin Response / Q000187:drug effects; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D008297:Male; D008620:Meprobamate / Q000097:blood / Q000494:pharmacology; D009125:Muscle Relaxants, Central / Q000097:blood / Q000494:pharmacology*; D015990:Placebo Effect; D012018:Reflex / Q000187:drug effects; D013216:Reflex, Startle / Q000187:drug effects
D002395:Catecholamines; D000697:Central Nervous System Stimulants; D009125:Muscle Relaxants, Central; D002328:Carisoprodol; D002110:Caffeine; D008620:Meprobamate