(klor'al hye'drate)
Aquachloral Supprettes, Noctec, Novochlorhydrate 
Classifications: anxiolytic, sedative-hypnotic;
Therapeutic: antianxiety
; sedative-hypnotic
Prototype: Secobarbital
Pregnancy Category: C
Controlled Substance: Schedule IV


500 mg capsules; 250 mg/5 mL, 500 mg/5 mL syrup; 324 mg, 500 mg, 648 mg suppositories


Produces "physiologic sleep" by mild cerebral depression with little effect on respirations or BP and little or no hangover.

Therapeutic Effect

Chloral hydrate in low doses is a sedative-hypnotic which does not affect sleep physiology (e.g., REM sleep).


Short-term management of insomnia, general sedation (especially in the young and the older adult), sedation before and after surgery, to reduce anxiety associated with drug withdrawal, and alone or with paraldehyde to prevent or suppress alcohol withdrawal symptoms.


Known hypersensitivity to chloral hydrate or chloral derivatives; severe hepatic, renal, or cardiac disease; rectal dosage form in patients with proctitis; oral use in patients with esophagitis, gastritis, gastric or duodenal ulcers; pregnancy (category C).

Cautious Use

History of intermittent porphyria, asthma, history of or proneness to drug dependence, depression, suicidal tendencies.

Route & Dosage

Adult: PO/PR 250 mg t.i.d. p.c.
Child: PO/PR 25–50 mg/kg/d divided q6–8h (max: 500 mg/dose)

Adult: PO/PR 500 mg–1 g 15–30 min before h.s. or 30 min before surgery
Geriatric: PO/PR 250 mg h.s.
Child: PO/PR 50 mg/kg 15–30 min before h.s. or 30 min before surgery (max: 1 g)

EEG Premedication
Child: PO/PR 20–25 mg/kg 30–60 min prior to procedure


  • Dilute liquid preparations in chilled fluids to minimize unpleasant taste.
  • Watch to see that drug is not cheeked and hoarded.
  • Moisten suppository with a water-based lubricant, such as K-Y jelly, prior to insertion.
  • Solutions are preserved in tightly covered, light-resistant containers.

Adverse Effects (≥1%)

Body as a Whole: Angioedema, eosinophilia, breath odor, leukopenia, ketonuria, renal and hepatic damage, sudden death. CV: Arrhythmias, cardiac arrest. GI: Nausea, vomiting, diarrhea, severe gastritis. CNS: Dizziness, motor incoordination, headache. Skin: Purpura, urticaria, erythematous rash, eczema, erythema multiforme, fixed drug eruptions. Special Senses: Conjunctivitis.

Diagnostic Test Interference

False-positive results for urine glucose with Benedict's solutions, and possibly with Clinitest but not with glucose oxidase methods (e.g., Clinistix, Diastix, TesTape). Possible interference with fluorometric test for urine catecholamines (if chloral hydrate is administered within 48 h of test) and urinary 17-OHCS determinations (by modification of Reddy, Jenkins, Thorn procedure).


Drug: Alcohol, barbiturates, paraldehyde, other cns depressants potentiate CNS depression; tachycardia may also occur with alcohol; increases anticoagulant effect of oral anticoagulants; furosemide IV can produce flushing, diaphoresis, BP changes.


Absorption: Readily from oral or rectal administration. Onset: 30–60 min. Peak: 1–3 h. Duration: 4–8 h. Distribution: Well distributed to all tissues; 70–80% protein bound; crosses placenta. Metabolism: In liver to the active metabolite trichloroethanol. Elimination: Primarily by kidneys; small amount excreted in feces via bile. Half-Life: 8–11 h.

Nursing Implications

Assessment & Drug Effects

  • Chloral hydrate is not intended for relief of pain. When used in the presence of pain, it may cause excitement and delirium.
  • Do not discontinue abruptly following prolonged use. Sudden withdrawal from dependent patients may produce delirium, mania, or convulsions.
  • Monitor for S&S of allergic skin reactions, which may occur within several hours or as long as 10 d after drug administration.
  • Evaluate patient's response to chloral hydrate and continued need for the drug.

Patient & Family Education

  • Do not ambulate without assistance until response to drug is known.
  • Avoid concomitant use of alcoholic beverages.
  • Avoid driving and other potentially hazardous activities while under the influence of chloral hydrate.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

© 2006-2022 Last Updated On: 11/28/2022 (0)
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