Recent research indicates that tiagabine, a selective ã-aminobutyric acid (GABA) reuptake inhibitor, has positive effect on sleep and next-morning alertness and performance in adult patients with primary insomnia.
Primary insomnia is characterized by difficulty initiating or maintaining sleep and/or nonrestorative sleep, which causes clinically significant distress or impairment in important areas of waking function.
The authors, writing in the journal Sleep Medicine (available online 2 November 2005) assert that since GABA is a major inhibitory neurotransmitter in the central nervous system and tiagabine increases synaptic availability of GABA, hypnotic properties would seem a likely dose-related effect.
The researchers evaluated the effect of tiagabine administered before bedtime at doses from 4 to 16 mg on sleep and next-morning alertness and psychomotor performance in adult patients with primary insomnia.
Fifty-eight middle-aged patients were randomized for the study. Results showed a significant dose-dependent increase in slow wave sleep percentage with all tiagabine doses, a trend toward a dose-dependent increase in total sleep time, and no effect on latency to persistent sleep.
The authors conclude that tiagabine increased slow wave sleep and reduced wake after sleep onset in a dose-dependent manner. Tiagabine dosages up to 8 mg did not compromise next-morning alertness and psychomotor performance in adult patients with primary insomnia. Further investigation of tiagabine doses up to 8 mg is warranted.
The authors suggest that additional studies with tiagabine are warranted to further investigate tiagabine's clinical effects in patients with insomnia. Also of interest are the potential differences associated with increases in slow wave sleep mediated by different neurotransmitter systems.