Understanding Restavit and Its Active Ingredient
Restavit is an over-the-counter medication primarily used for the temporary relief of insomnia. Its effectiveness as a sleep aid stems from its single active ingredient: doxylamine succinate. Typically, each Restavit tablet contains doxylamine succinate in a specific strength. While sold under the brand name Restavit in countries like Australia, doxylamine succinate is a common compound found in various nighttime sleep aids and cold medicines globally, including brands like Unisom and in formulations like NyQuil.
How Doxylamine Succinate Works
Doxylamine succinate belongs to a class of drugs known as first-generation ethanolamine antihistamines. Its primary function in the body is to act as an antagonist or inverse agonist of the histamine H1 receptor. Histamine is a neurotransmitter that promotes wakefulness. As a first-generation antihistamine, doxylamine can cross the blood-brain barrier and block these H1 receptors in the central nervous system. This action inhibits histaminergic signaling, leading to sedative and hypnotic (sleep-inducing) effects.
In addition to its antihistamine properties, doxylamine is also a potent anticholinergic, meaning it blocks the action of acetylcholine, another neurotransmitter. This contributes to some of its side effects, such as dry mouth and urinary retention.
Proper Use and Dosage
Restavit is intended for the short-term management of sleeplessness and to help re-establish a regular sleep pattern. It is not recommended for use for more than a few consecutive days. The appropriate dosage should be taken with water about 20-30 minutes before bedtime. It is crucial to ensure you have time for a full night's sleep (7 to 8 hours) after taking the medication to avoid significant next-day drowsiness. Restavit should not be given to children under 12 years of age.
Potential Side Effects and Warnings
Like all medications, Restavit can cause side effects. The most common is a "hangover effect," which includes next-day drowsiness, dizziness, grogginess, and lack of coordination. Due to its relatively long half-life of about 10-12 hours, these effects can be more pronounced compared to other sleep aids with shorter half-lives.
Other common side effects, largely due to its anticholinergic properties, include:
- Dry mouth, nose, and throat
- Blurred vision
- Constipation
- Difficulty urinating
- Muscle weakness
It is essential to avoid alcohol and other central nervous system depressants (like sedatives or tranquilizers) while taking Restavit, as they can intensify the sedative effects. Due to the risk of drowsiness and impaired coordination, you should not drive or operate heavy machinery after taking this medication.
Long-term, continuous use of doxylamine is discouraged as it can lead to tolerance, and has been associated with an increased risk of cognitive decline and dementia in older adults. If sleeplessness persists for more than two weeks, it could be a symptom of a serious underlying medical condition, and you should consult a doctor.
Comparison with Other OTC Sleep Aids
| Feature | Doxylamine Succinate (Restavit, Unisom) | Diphenhydramine (Benadryl, ZzzQuil) |
|---|---|---|
| Primary Use | Short-term insomnia | Allergies, cold symptoms, occasional insomnia |
| Drug Class | First-generation antihistamine | First-generation antihistamine |
| Typical Sleep Dose | Varies by product | Varies by product |
| Half-Life | ~10-12 hours | ~4-8 hours |
| Next-Day Drowsiness | More likely due to longer half-life | Less likely, but still possible |
| Use in Children | Not for children under 12 | Can be used for allergies in children (dose varies) |
While both doxylamine and diphenhydramine are effective for occasional insomnia, the choice between them may come down to individual response and concern about next-day grogginess. Diphenhydramine's shorter half-life may give it an advantage for those worried about a 'hangover' effect.
Conclusion
In summary, the active substance in Restavit is doxylamine succinate, a first-generation antihistamine that induces sleep by blocking histamine's wakefulness-promoting effects in the brain. It is an effective solution for short-term insomnia but should be used cautiously due to potential side effects like significant next-day drowsiness and the risks associated with long-term use. Always adhere to the recommended dosage and duration, and consult a healthcare professional for persistent sleep problems.
For more detailed consumer information, you can refer to the NPS MedicineWise leaflet.
