In Hong Kong, most medications used to treat insomnia are prescription-only medicines and should be taken under a doctor’s supervision.
Hypnotics are medications that act on the central nervous system (CNS) to induce sleep. These medications do not address the root cause of insomnia and should be prescribed by a doctor, used at the lowest effective dose, and taken for the shortest possible duration. They are suitable for short-term management of severe and disabling insomnia.
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Common Types of Sleeping Medicines*
Common hypnotics used in the treatment of insomnia include benzodiazepines, dual orexin receptor antagonist (e.g. daridorexant and lemborexant), zopiclone and zolpidem. Other drugs that are used in the treatment of insomnia include chloral hydrate and sedating antihistamines (e.g. promethazine).
1.Benzodiazepines
Benzodiazepines can be classified as long-acting or short-acting, depending on their duration of action. Those commonly used in management of insomnia include:
(a) Long-acting benzodiazepines – diazepam, pinazepam;
(b) Short-acting benzodiazepines – lorazepam, midazolam, triazolam.
Benzodiazepines shorten the time to fall asleep, decrease awakenings during the night and increase total sleeping time. Short-acting benzodiazepines are often used if you have difficulty in falling asleep as they have a smaller chance of producing ‘hangover feeling’ the next day. Long-acting benzodiazepines are indicated in patients with poor sleep maintenance (e.g. early morning waking), and when an anxiolytic effect is needed during the day.
Due to the development of tolerance, dependence and withdrawal symptoms, benzodiazepines should be used to treat insomnia only when it is severe, disabling, or causing the patient extreme distress. Benzodiazepines, when used as hypnotics, should be administered at the lowest effective dose for the shortest possible duration, which should not exceed 4 weeks.
There is also a potential risk of complex sleep-related behaviors such as sleep driving, making phone calls, or preparing and eating food while asleep in patients receiving benzodiazepines.
2.Chloral Hydrate
Chloral hydrate is a hypnotic and sedative. It can cause prolonged drowsiness lasting till the next day and patients should not drive or operate machinery after taking this medicine. The most common adverse effects reported with chloral hydrate include gastric irritation, abdominal distension, flatulence, drowsiness, light-headedness, headache, excitement, and confusion.
It has been used as a short-term sedative, in particular for children, but potential carcinogenicity was once a concern and limited its use. The use of chloral hydrate in children and adolescents is not generally recommended, and if used should be under the supervision of a medical specialist. Treatment should be for the shortest duration possible and should not exceed the maximum treatment period of 2 weeks.
3. Dual Orexin Receptor Antagonist (DORA)
Dual orexin receptor antagonists (e.g. daridorexant, lemborexant) represent a newer class of insomnia medications that work by blocking orexin, a brain chemical that promotes wakefulness, thereby suppressing the wake drive and promoting sleep. The length of treatment should be for the shortest duration possible.
Dual orexin receptor antagonists (DORA) are central nervous system (CNS) depressants that can impair daytime wakefulness even when used as prescribed. CNS depressant effects may persist in some patients for up to several days after discontinuing the medicine. DORA have the potential to cause next-day somnolence. Worsening of depression and suicidal thoughts and actions (including completed suicides) have been reported in primarily depressed patients treated with hypnotics.
Sleep paralysis and hallucinations (including vivid and disturbing perceptions) can occur with the use of DORA. Complex sleep behaviors, including sleep walking, sleep driving, and engaging in other activities while not fully awake (e.g., preparing and eating food, making phone calls, having sex), have also been reported to occur with the use of hypnotics, including orexin receptor antagonists.
4. Sedating Antihistamines
Some sedating antihistamines such as promethazine, have been used for short-term sedation. They may cause drowsiness on the next day and patients should not drive or operate machinery after taking these medicines. The most common adverse effect of sedating antihistamines includes CNS depression, lassitude, dizziness, and incoordination. Other adverse effects that are more common with sedating antihistamines include headache, and antimuscarinic effects, such as dry mouth, blurred vision, difficulty in urination or urinary retention, constipation. Sedating antihistamines should be used with caution in patients with prostatic hyperplasia, narrow-angle glaucoma, asthma, bronchitis, liver or renal dysfunction, myasthenia gravis.
5. Zopiclone
Zopiclone is used as a hypnotic in the short-term management of insomnia. Because the risk of abuse and dependence increases with the duration of treatment, treatment with zopiclone should be administered at the lowest effective dose, and usually not to exceed 7 to 10 consecutive days. Use of Zopiclone for more than 2 to 3 consecutive weeks requires complete patient re-evaluation. It is short-acting and less likely to cause ‘hangover feeling’ than short-acting benzodiazepines. However, there is little evidence to show any clinical advantages of zopiclone over benzodiazepines in terms of tolerance, dependence or withdrawal symptoms
Complex sleep behaviour, including sleep walking and other associated behaviours such as sleep driving, preparing and eating food, making phone calls or having sex, with amnesia for the event, have been reported in patients who had taken Zopiclone and were not fully awake. The use of alcohol and other CNS-depressants with Zopiclone appears to increase the risk of such behaviours.
6.Zolpidem
Zolpidem tartrate is used as a hypnotic in the short-term management of insomnia. It is reported to have similar sedative properties as the benzodiazepines, but very little anxiolytic and muscle relaxant properties in comparison. Zolpidem has a rapid onset and short duration of hypnotic action, but there is little evidence to show any advantage over short-acting benzodiazepines in terms of ‘hangover feeling’, or its potential to induce tolerance or withdrawal symptoms or dependence.
Complex sleep behaviour, including sleep walking and other associated behaviours such as sleep driving, preparing and eating food, making phone calls or having sex, with amnesia for the event, have been reported in patients who had taken zolpidem and were not fully awake. The use of alcohol and other CNS-depressants with zolpidem appears to increase the risk of such behaviours.
Because the risk of abuse and dependence increases with the duration of treatment, it is important that zolpidem should be administered at the lowest effective dose, and treatment should be as short as possible and should not exceed 4 weeks.
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