Ben Goldacre speaking at Nerdstock, via George Dvorsky:
Near the end of the video, Dr. Goldacre mentions a study of the muscle relaxant carisoprodol. Subjects were divided into six groups, three were given the drug and three received a placebo. Some groups were told the drug was a relaxant, others a stimulant, and the remainder were given no information about the drug. After administering the drug, blood concentration was measured for carisoprodol and meprobamate (its metabolite):
The placebo effect is still poorly understood. It's a fascinating subject for me. Is it possible to make a drug more effective simply by saying the right things to the patient? If so, perhaps the dosage could be lowered with a commensurate reduction of side effects. Or, could the side effects themselves be mitigated by priming the patient with counter-factual information? Would you prefer to be told lies at the hospital if it meant less severe side effects?