How does chloral hydrate work?
Chloral hydrate has sedative and sleep-promoting properties. It influences the inhibitory properties of the body’s own messenger substance gamma-aminobutyric acid (GABA).
In the human brain, GABA is the most important messenger substance of inhibitory synapses (connection between one nerve cell and the next). When GABA binds to its receptor, it has a calming, anxiety-relieving and sleep-promoting effect. Chloral hydrate intensifies these effects.
Chloral hydrate rarely causes paradoxical reactions (such as agitation, insomnia) and hardly affects the normal course of sleep.
How quickly does chloral hydrate work?
Chloral hydrate is rapidly broken down in the body to trichloroethanol (the actual active ingredient) and ineffective trichloroacetic acid. The effect sets in quickly and lasts for about seven hours.
What are the side effects of chloral hydrate?
Occasional side effects include confusion, nausea and allergic reactions.
Like all halogenated hydrocarbons, chloral hydrate can damage the kidneys, liver and heart. There is a risk that the heart will react more sensitively to catecholamines (activating messenger substances).
Because chloral hydrate accelerates its own breakdown, its effect can diminish significantly after just a few days.
Like almost all sleeping pills, chloral hydrate can also be addictive. It should therefore only be taken on a short-term basis.
You can find out more about these and other side effects in the package leaflet for your chloral hydrate medication. Contact your doctor or pharmacist if you suspect any undesirable side effects.
Overdosage
The maximum daily dose must not exceed 1.5 to two grams, depending on the preparation. An overdose of chloral hydrate can result in loss of consciousness, cardiac arrhythmia and breathing problems.
The lethal dose is between six and ten grams of chloral hydrate.
When is chloral hydrate used?
Chloral hydrate is approved in Germany and Switzerland for the short-term treatment of sleep disorders. In Switzerland, it may also be used to treat nervous agitation.
How chloral hydrate is taken
Chloral hydrate is available in various dosage forms. Chloral hydrate soft capsules are registered in Germany. A solution is commercially available in Switzerland.
The previously available chloral hydrate enemas (chloral hydrate rectioles) for rectal administration into the rectum are no longer available.
Chloral hydrate soft capsules
Adults with insomnia initially take one to two soft capsules (equivalent to 0.25 to 0.5 grams of chloral hydrate) with a glass of water about half an hour before going to bed.
If you have problems swallowing the soft capsules, soak them briefly in lukewarm water beforehand.
Chloral hydrate solution
The usual dosage as a sleeping aid is between 0.5 and one gram of chloral hydrate (one to two measuring spoons of five milliliters) according to the Swiss specialist information. The maximum daily dose must not exceed two grams.
For restlessness, 0.25 grams (half a measuring spoon) of the solution three times a day after meals is recommended.
If the bitter taste bothers you, dilute the solution well with cold water before taking it.
When should chloral hydrate not be taken?
Chloral hydrate should generally not be used in the following cases:
- if you are hypersensitive or allergic to the active substance or any of the ingredients of the medicine
- if you have severe liver, kidney or heart disease
- with simultaneous treatment with coumarin-type anticoagulants (e.g. warfarin, phenprocoumon)
- severe disorders of respiratory function
- obstructive sleep apnea syndrome
- in the metabolic disorder porphyria (applies to the chloral hydrate solution)
- in gastritis (applies to the chloral hydrate solution)
- during pregnancy and breastfeeding
- in children and adolescents under 18 years of age (applies to the chloral hydrate soft capsules)
These interactions can occur with chloral hydrate
Due to its depressant properties, numerous interactions with other drugs with a depressant effect are known. These include
- Opioids (strong painkillers such as hydromorphone and fentanyl)
- Antipsychotic drugs (such as olanzapine and clozapine)
- Anti-anxiety drugs (such as pregabalin and alprazolam)
- Anti-epileptic drugs (such as primidone and carbamazepine)
- Older anti-allergic drugs (such as diphenhydramine and doxylamine)
Chloral hydrate is suspected of prolonging the QT interval of the heart. This is a certain period of time in the ECG. The combination with other drugs that prolong the QT interval should therefore be avoided. These include
- Anti-arrhythmic drugs (such as quinidine and sotalol)
- certain antibiotics (such as macrolides and fluoroquinolones)
- Antimalarials (such as halofantrine and quinine)
- Antipsychotic drugs (such as sertindole, haloperidol and melperone)
Chloral hydrate accelerates the metabolism of amitriptyline (antidepressant). It can also lower the blood level of phenytoin (anti-epileptic drug).
In people who use certain antidepressants (fluoxetine or monoamine oxidase inhibitors = MAO inhibitors), the duration of the effect of chloral hydrate may be prolonged.
Alcohol increases the soporific effect of chloral hydrate and dilates the blood vessels.
Chloral hydrate in children: What should be considered?
The chloral hydrate solution registered in Switzerland is also approved for children, including babies. There is no lower age limit. The dosage is based on body weight.
As a sleeping pill, the usual dose is between 30 and 50 milligrams per kilogram of body weight before going to bed.
If chloral hydrate is used as a sedative, 25 milligrams per kilogram of body weight is sufficient for minors. This amount is divided into three to four doses during the day.
The maximum recommended single dose is one gram of chloral hydrate.
Preparation in the pharmacy
In Germany and Austria, doctors can prescribe a magistral chloral hydrate syrup (juice) for children. It is prepared in the pharmacy.
If your child refuses to take the bitter syrup, dilute it with cold water. It is also helpful to drink more water.
How to obtain medication with chloral hydrate
Chloral hydrate is only available on prescription in Germany and Switzerland. There are currently no ready-to-use preparations containing the active ingredient available in Austria.
Magistral chloral hydrate preparations are also subject to prescription in all three countries.