Zopiclone
Zopiclone branded as Zimovane – is a hyposedative, non-benzodiaepine cyclo-pyrrolone, which is also an agonist at the type A -aminobutyric acid (GABAA) meaning that it is known to produce activity at the GABAA receptor complex . In addition, the duration of zopiclone’s effects and action is determined by its pharmacokinetic profile, which suggests a delayed elimination time when compared to the hypnotic agent Zaleplon. Importantly, it is a commonly prescribed hypnotic drug which is usually employed – short-term – to treat sleeping difficulties. It is considered a ‘Z-drug’, having notable high-affinity binding to the GABA receptor [6]. Comparatively, zolpidem and zaleplon bind to the subunit of the GABA receptors.
It metabolises to two distinct metabolites: N-oxide, and N-desmethyl-zopiclone [8]. Once ingested,it becomes approximately 80% bioavailable [9], with between 40-80% of it being bound to plasma proteins [8; 10; 2]. Furthermore, the N-oxide metabolite has been found to exhibit pharmacological activity in the body; with the N-desmethyl-zopiclone metabolite showing no pronounced activity [8]. The elimination half-life of zopiclone, along with its active metabolite, has been noted as being between 3.5-6.5 hours [7]. Other reviews have indicated half-life of 5.1 hours [1].Along with zolpidem, is a prescription-only medicine (POM).
Safety
The safety profile of zopiclone is addressed via the assessment of its rebound insomnia potential, withdrawal and dependence on it and residual effects and tolerability [1]. Insomnia in North America and the UK is between 5-15% with around 40% also experiencing daytime sleepiness [9]. Z-drugs, including zopiclone, have the potential to cause spontaneous reactions, such as acute excitement, vivid dreams, along with an increase in hostile, anxious and aggressive behaviour [7].