Saccadic eye velocity after selective GABAergic treatment with tiagabine in healthy volunteers

Background: Saccadic eye velocity (SEV) has been shown to be a
reliable neurophysiological tool for the assessment of
gamma-aminobutyric acid GABA(A) receptor sensitivity.
Administration of benzodiazepines targeting the GABA(A) receptor
decreases SEV in healthy volunteers. Tiagabine is a new
antiepileptic drug which acts via selective blockade of GABA
reuptake. Therefore, we examined the effects of tiagabine on
saccade parameters. Methods: SEV was analyzed in 8 healthy
volunteers before and after 7 days of tiagabine treatment. Subjects
received tiagabine in a daily dose of 15 mg. Saccades were measured
using a noninvasive infrared oculographic device. Amplitude,
latency, and SEV were analyzed as a function of treatment and
target eccentricity. Results: SEV and saccade latency increased
with target amplitude. Treatment with tiagabine had no significant
effect on SEV and saccade amplitude. A trend was found for
increased latencies after tiagabine. Conclusion: In contrast to
findings with benzodiazepines, tiagabine treatment had no impact on
SEV in healthy volunteers. The subchronic tolerance effects or the
different site of action on the GABA(A)/BZD receptor complex may
account for this deviating profile. Copyright (C) 2005 S. Karger
AG, Basel.