Modulation of human motor cortex excitability by quetiapine.
BACKGROUND
Quetiapine is increasingly used for the treatment of patients with psychosis and bipolar disorder. However, the neurobiological mechanisms, which may account for the favourable risk/benefit profile of this drug, are not entirely understood.


OBJECTIVE
Transcranial magnetic stimulation was used to investigate the effects of acute and repeated administration of quetiapine on cortical excitability in healthy volunteers.


METHODS
Within a double-blind, placebo-controlled, randomized cross-over design motor threshold, intracortical inhibition, intracortical facilitation and cortical silent period were studied in 15 healthy volunteers before and after a single dose of placebo and 100 mg quetiapine. Additional measurements were performed after 5 days of daily intake of 100 mg quetiapine.


RESULTS
We observed a significant prolongation of the cortical silent period after a single dose of quetiapine, whereas the placebo had no effects. After repeated administration, there was a trend towards CSP prolongation, which did not reach significance. However, plasma concentrations at this time point were relatively low, as measurements were performed 15 h after the last drug intake. Other parameters of cortical excitability remained unaffected.


CONCLUSIONS
By lengthening CSP without affecting MT, ICI and ICF, quetiapine demonstrates a unique neurophysiological profile which differs distinctively from brain excitability profiles of typical antipsychotics such as haloperidol. Provided that the CSP prolongation reflects the antipsychotic potential of quetiapine, TMS may be developed as a tool to monitor neurobiological effects of quetiapine treatment in schizophrenic patients and to explore the efficacy of other antipsychotic drugs with a similar mode of action.
Department of Psychiatry, University of Regensburg, Universitaetsstrasse 84, D-93053 Regensburg, Germany. Berthold.Langguth@medbo.de
Berthold
B
Langguth
Peter
P
Eichhammer
Claus
C
Spranz
Michael
M
Landgrebe
Ulrich
U
Frick
Philipp
P
Sand
Göran
G
Hajak
D000328:Adult; D014150:Antipsychotic Agents / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D018592:Cross-Over Studies; D003987:Dibenzothiazepines / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D004576:Electromyography; D019054:Evoked Potentials, Motor; D005260:Female; D006801:Humans; D008297:Male; D009044:Motor Cortex / Q000187:drug effects* / Q000502:physiology; D000069348:Quetiapine Fumarate; D050781:Transcranial Magnetic Stimulation
D014150:Antipsychotic Agents; D003987:Dibenzothiazepines; D000069348:Quetiapine Fumarate