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Chloral Hydrate


Pronunciation: KLOR-al HYE-drate
Class: Sedative, Hypnotic, Nonbarbiturate

Trade Names

- Capsules, oral 500 mg

Chloral Hydrate-Odan (Canada)


Acts as a sedative and hypnotic. Action is confined to the cerebral hemispheres.

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Readily absorbed.


Widely distributed.


Metabolized to trichloroethanol (active), which is then converted in the liver and kidney to trichloroacetic acid (inactive).


The half-life is 7 to 11 h (trichloroethanol). Metabolites are excreted in urine and bile.

Indications and Usage

Management of short-term insomnia; sedation; prevention or suppression of alcohol withdrawal symptoms; reduce anxiety associated with withdrawal of drugs such as narcotics or barbiturates; preoperatively or prior to electroencephalographic evaluation to allay anxiety and produce sedation and/or sleep.


Hypersensitivity or idiosyncratic reaction to any component of the product; severe renal or hepatic impairment.

Dosage and Administration

Alcohol Withdrawal

PO 500 mg to 1 g every 6 h, if needed (max, 2 g/day).


PO 500 mg to 1 g 15 to 30 min before bedtime (max, 2 g/day).


PO 250 mg 3 times daily after meals (max, 2 g/day).

General Advice

  • Administer with a full glass of water or liquid to help prevent GI upset problems.


Store at 59° to 86°F. Do not freeze.

Drug Interactions

Alcohol, CNS depressants

Additive CNS depression may occur. Rarely, disulfiram-like reactions may occur with alcohol ingestion. If coadministration cannot be avoided, use with caution.

Furosemide (IV)

Administration within 24 h of chloral hydrate may lead to diaphoresis, hot flashes, tachycardia, and hypertension. Consider an alternative to chloral hydrate.

Oral anticoagulants (eg, warfarin)

Anticoagulant effects may be increased transiently. Monitor anticoagulant activity.


May reduce effects of phenytoin. Based on current data, routine clinical monitoring should be sufficient.


Sedative effects of chloral hydrate may be increased. If coadministration cannot be avoided, adjust the chloral hydrate dose to minimize sedation.

Sodium oxybate

Concurrent use may result in an increase in sleep duration and CNS depression, resulting from additive pharmacologic effects. Coadministration is contraindicated.

Laboratory Test Interactions

May cause false-positive urine glucose test results with Benedict solution or cupric sulfide tablets (eg, Clinitest ) but not with enzyme-based tests (eg, Clinistix , Tes-tape ); altered urinary 17-ketosteroid values when using the Reddy-Jenkins-Thorn procedure; false-positive phentolamine test results; results of fluorometric tests for urine catecholamines may be altered (do not administer chloral hydrate 48 h before this test).

Adverse Reactions


Ataxia; dizziness; residual sedation (“hangover effect”); somnambulistic reaction, including disorientation and incoherence.


Angioedema; bullous lesions; eczema; erythema multiforme; purpura; scarlatiniform or erythematous rash; urticaria.


Gastric irritation manifested by diarrhea, nausea, and vomiting (frequent).





Closely monitor elderly and/or debilitated patients for impaired motor and/or cognitive performance or unusual sensitivity to the sedative/hypnotic effects of chloral hydrate.


Category C .


Excreted in breast milk.


Safety and efficacy not established.


Impaired motor and/or cognitive performance after repeated exposure or unusual sensitivity to sedative/hypnotic drugs is a concern in elderly and/or debilitated patients.


Anaphylaxis and angioedema may occur as early as the first dose.

Special Risk Patients

Use with caution in patients who are depressed, have suicidal tendencies, or have a history of drug abuse.

Acute intermittent porphyria

Attacks may be precipitated in susceptible patients.

Cardiac disease

Do not use large doses in patients with severe cardiac disease.

Drug dependency

May be habit forming. Use with caution in patients with a history of drug or alcohol addiction. In addition, prolonged use may produce drug tolerance and physical and/or psychological dependence.

GI disorders

Avoid use in patients with esophagitis, gastritis, or gastric or duodenal ulcers.

Prolonged administration

Gastritis, skin eruptions, or parenchymatous renal damage may develop following prolonged administration.

Sleep-related behavior

Behaviors may include sleep-driving as well as making phone calls and preparing and eating food while asleep.

Withdrawal symptoms

Discontinue gradually to prevent withdrawal symptoms.



Areflexia, cardiac arrhythmias, coma, death from respiratory failure or hypertension, esophageal stricture, gastric necrosis and perforation, GI hemorrhage, hepatic and renal impairment with resulting transient jaundice and/or albuminuria, hypotension, hypothermia, miosis, muscle flaccidity, respiratory depression, vomiting.

Patient Information

  • Instruct patients to take the capsule with full glass of water or other liquid.
  • Advise patients that medication will be discontinued gradually to prevent withdrawal symptoms, including CNS excitation with tremor, anxiety, hallucinations, or delirium.
  • Instruct patients to report these symptoms to their health care provider: abdominal pains, GI problems, irregular heartbeat or palpitations, rash or unusual bleeding or bruising, visual changes, or yellowing of skin or eyes.
  • Advise patients that the drug may cause drowsiness or dizziness, and to use caution when driving or performing other tasks requiring mental alertness.
  • Caution patients to avoid intake of alcoholic beverages and other CNS depressants, such as barbiturates and narcotics.

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