💊 Z-Drugs (Zopiclone)

Z-drugs are a class of non-benzodiazepine hypnotics, primarily used for the short-term management of insomnia. They are structurally distinct from benzodiazepines but share a similar mechanism of action.

Zopiclone acts as a GABA-A receptor agonist, enhancing the inhibitory effects of gamma-aminobutyric acid (GABA) in the central nervous system. This leads to neuronal hyperpolarisation, reducing neuronal excitability and promoting sedation, anxiolysis, and muscle relaxation. It has a relatively short half-life, making it suitable for sleep induction.

Zopiclone is indicated for the short-term treatment of insomnia, particularly when the insomnia is severe, disabling, or causing extreme distress. It is generally reserved for situations where non-pharmacological interventions have been ineffective. Due to the risk of dependence and tolerance, its use should be limited to a few days to a maximum of four weeks.

Contraindications include severe hepatic impairment, severe respiratory insufficiency, sleep apnoea syndrome, and myasthenia gravis. It should also be avoided in patients with a history of paradoxical reactions to hypnotics or sedatives. Caution is advised in elderly patients due to increased sensitivity and risk of falls.

Common adverse effects include a bitter or metallic taste, drowsiness, dizziness, and dry mouth. More serious but less common effects can include anterograde amnesia, paradoxical reactions (e.g., agitation, hallucinations), and dependence, especially with prolonged use. Withdrawal symptoms can occur upon abrupt discontinuation.

Monitoring is primarily clinical, assessing the efficacy of sleep improvement and the presence of adverse effects. Patients should be monitored for signs of dependence or tolerance, and for any paradoxical reactions. Regular review of the need for continued treatment is crucial.

When prescribing, always check for allergies, especially to other hypnotics. Counsel patients on the short-term use, the risk of dependence, and the importance of not exceeding the prescribed dose. Warn about driving or operating machinery due to drowsiness and potential interactions with alcohol or other CNS depressants.

Z-drugs are not first-line for insomnia; CBT-I is preferred. Emphasise the maximum treatment duration (4 weeks) to minimise dependence. Be aware of the 'hangover effect' and the bitter taste. Recognise that paradoxical reactions are a contraindication for future use of Z-drugs or benzodiazepines.

SBA questions often focus on the short-term nature of Z-drug use and the risks of dependence and withdrawal. Scenarios might describe a patient with chronic insomnia and ask about the most appropriate management, testing knowledge of non-pharmacological first-line treatments. Questions may also highlight paradoxical reactions or the bitter taste side effect.