Back to the Top
Hi all,
I was wondering if anyone knows of any recent studies on the therapeutic
effects of administration of placebos. Actually not just recent but
any well regarded studies.
Thanks
Oliver Daly
Back to the Top
The following two citation classic papers provided the mechanistic basis
for the effect of placebo and route of administration on analgesic
response. As they might be of general interest, I have cut and pasted the
abstracts. I hope this helps, or at least makes interesting reading!
1. JD Levine, NC Gordon and HC Fields. The mechanism of placebo
analgesia. Lancet, 2 (8091): 654-7 (1978)
The effect of naloxone on dental postoperative pain was studied to examine
the hypothesis that endorphins mediate placebo analgesia. All patients had
extraction of impacted mandibular third molars with diazepam, N2O, and
local block with mepivacaine. 3 h and 4 h after surgery naloxone or a
placebo was given under randomised, double-blind conditions. Pain was
evaluated on a visual analogue scale. Patients given naloxone reported
significantly greater pain than those given placebo. Patients given
placebo as their first drug was either placebo responders, whose pain was
reduced or unchanged, or nonresponders whose pain increased. Naloxone
given as a second drug produced no additional increase in pain levels in
nonresponders but did increase pain levels of placebo responders.
Nonresponders had a final mean pain rating identical to that of responders
who received naloxone as their second drug. Thus the enhancement of
reported pain produced by naloxone can be entirely accounted for by its
effect on placebo responders. These data are consistent with the
hypothesis that endorphin release mediates placebo analgesia for dental
postoperative pain.
2. JD Levine and NC Gordon. Influence of method of drug
administration on analgesic response. Nature, 312: 755-6 (1984)
The appropriate control group in studies of placebo-induced analgesia has
not been established. A traditional control has been a 'no treatment' or
natural-history group. In some studies, the natural-history group receives
a hidden infusion of vehicle, a physiologically inactive substance such as
saline solution, to eliminate differences in expectation of the outcome on
the part of the experimenter. To evaluate whether 'hidden' as well as open
infusion of vehicle can elicit a placebo response, we have now tested a
different natural-history group, one which received an infusion of vehicle
from a syringe pump controlled by a programmable timer. A comparison of
these two control groups provides evidence that hidden infusion of vehicle
can elicit a placebo response. Use of this new control group also
permitted a clear distinction between a naloxone-antagonizable component
of placebo analgesia and naloxone antagonism of endorphin-mediated
analgesia induced by surgical stress. Our study underscores the power of
the placebo and emphasizes that even the most subtle cues can elicit a
placebo response.
Back to the Top
> ------------
> Iwaswondering if anyone knows of any recent studies on the therapeutic
> effects of administration of placebos. Actually not just recent but any
> well regarded studies.
> ------------
I responded to a query in the newsgroup and I just realized that I
failed to mention that placebos/analgesia are outside my area of
specialization. I hope I did not convey such an impression with my
response.
Thanks!
vikram
Back to the Top
> I was wondering if anyone knows of any recent studies on the therapeutic
> effects of administration of placebos. Actually not just recent but
> any well regarded studies.
The following papers discuss models for the placebo response and estimates
of its
magnitude in Alzheimer's disease and rheumatoid arthritis.
Holford NHG, Peace K. Methodologic aspects of a population
pharmacodynamic model for cognitive effects in Alzheimer patients
treated with tacrine. Proc. Natl. Acad. Sci. USA. 89:11466-11470 1992
Holford NHG, Peace K. Results and validation of a population
pharmacodynamic model for cognitive effects in Alzheimer patients
treated with tacrine. Proc. Natl. Acad. Sci. USA. 89:11471-11475 1992
Holford NHG, Peace K. The effect of tacrine and lecithin in Alzheimer's
disease. A population pharmacodynamic analysis of five clinical trials.
Europ. J. Clin. Pharmacol. 1994; 47:17-24
Holford NHG, Williams PEO, Muirhead GJ, Mitchell AM, York A.
Population pharmacodynamics of romazarit. Br. J. Clin. Pharmacol. 1995;
39:313-320
--
Nick Holford, Dept Pharmacology & Clinical Pharmacology
University of Auckland, Private Bag 92019, Auckland, New Zealand
email:n.holford.at.auckland.ac.nz tel:+64(9)373-7599x6730 fax:373-7556
http://www.phm.auckland.ac.nz/Staff/NHolford/nholford.html
PharmPK Discussion List Archive Index page
Copyright 1995-2010 David W. A. Bourne (david@boomer.org)