Incidence of clinically significant responses to zolpidem among patients with
disorders of consciousness: a preliminary placebo controlled trial.
Author(s): Whyte J, Myers R.
Affiliation(s): Moss Rehabilitation Research Institute, 2nd Floor, West Building, 60 E. Township
Line Road, Elkins Park, PA 19027, USA.
Publication date & source: 2009, Am J Phys Med Rehabil. , 88(5):410-8
OBJECTIVES: The common hypnotic, zolpidem, has been reported to temporarily
restore consciousness to individuals in the chronic vegetative state. In drug
responders, repeated dosing appears to maintain consciousness. The frequency of
such responses, however, is unknown and is important both to guide clinical use
and to plan further research on the mechanisms underlying drug response. The
objectives of this study were to obtain an estimate of the frequency of
clinically significant responses among individuals with disorders of
consciousness, to determine whether less obvious drug responses are present among
"nonresponders," and to identify clinical features characteristic of zolpidem
responders.
DESIGN: Participants were individuals in the vegetative or minimally conscious
state at least 1 month after brain injury. Each participant was studied
individually in a double-blind, placebo-controlled, crossover design, once on
zolpidem (10 mg per feeding tube) and once on placebo. Each assessment involved
baseline administration of the Coma Recovery Scale-Revised, followed immediately
by administration of the study drug, followed by 5 hourly readministrations of
the Coma Recovery Scale-Revised. A replication pair of assessments was available
for drug responders.
RESULTS: : One of 15 participants (6.7%) demonstrated a clinically significant
response, which altered his assessment from the vegetative state to the minimally
conscious state, and this result was repeated in the replication assessment. The
remaining 14 participants showed no evidence of a subclinical response to the
drug.
CONCLUSION: These results confirm that clinically significant responses to
zolpidem among individuals with disorders of consciousness do occur in a minority
of patients and can be replicated. Failure to find a trend toward improved
performance on zolpidem among nonresponders suggests a bimodal rather than a
graded response to the drug. The fact that only one drug responder was identified
in this small study prevents assessment of features characteristic of drug
responders.
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