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Pregnancy Category: D
ClassificationTherapeutic: sedative hypnotics
Preoperative sedative and in other situations in which sedation may be required.Hypnotic for short-term treatment of insomnia.Psychiatric interviews.Wada testing (intracarotid administration to determine hemispheric locus of language dominance prior to epilepsy surgery).
Produces all levels of CNS depression:
- Depresses sensory cortex,
- Decreases motor activity,
- Alters cerebral function.
Inhibits transmission in the CNS and raises seizure threshold.
Absorption: Well absorbed after IM administration.
Distribution: Rapidly and widely distributed; concentrates in brain, liver, and kidneys. Readily crosses placenta; small amounts enter breast milk. Moderately bound to plasma proteins.
Metabolism and Excretion: Mostly metabolized by the liver.
Half-life: 16–40 hr.
Time/action profile (sedation)
|IM||30–45 min||rapid||6–8 hr|
|IV||several min||rapid||6–8 hr|
Contraindicated in: Hypersensitivity; Dyspnea or airway obstruction; Comatose patients; Pre-existing CNS depression; Severe hepatic dysfunction; Porphyria; Obstetric / Lactation: Not recommended.
Use Cautiously in: History of suicide attempts or substance abuse ; Debilitated patients (use smaller doses); Patients using alcohol or drugs that cause CNS depression; Patients with hepatic or renal impairment (dose should be reduced); Acute or chronic pain (paradoxical excitement may occur); Hypoadrenalism (↓ effects of corticosteroids); Pediatric: Safety not established in children <6 yr; Geriatric: Appears on Beers list. Geriatric patients are at increased risk for excitement, confusion, CNS depression; use smaller doses).
Adverse Reactions/Side Effects
Central nervous system
- drowsiness (most frequent)
- abnormal thinking
- CNS depression
- bronchospasm (IV only) (life-threatening)
- laryngospasm (IV only) (life-threatening)
- respiratory depression
- angioedema (life-threatening)
- exfoliative dermatitis
- pain or sterile abscess at IM site
- phlebitis at IV site
- hypersensitivity reactions including Stevens-Johnson syndrome (life-threatening)
Drug-Drug interactionAdditive CNS depression with other CNS depressants including alcohol, antidepressants, antihistamines, opioid analgesics, and other sedative/hypnotics.Sedation may be prolonged with MAO inhibitors and valproic acid.Induces hepatic enzymes that metabolize other drugs, decreasing their effectiveness, including hormonal contraceptives,furosemide, disopyramide, propafenone, methadone, cimetidine, cyclosporine, tacrolimus, rifampin, estrogen, chloramphenicol, acebutolol, propranolol, metoprolol, timolol, doxycycline, corticosteroids, tricyclic antidepressants, warfarin, theophylline, and quinidine.Concomitant use of kava, valerian, skullcap, chamomile, or hops can ↑ CNS depression.St. John's wort may ↓ barbiturate effect.
Intramuscular Intravenous (Adults) Sedative—30–50 mg 2–3 times daily; hypnotic—65–200 mg at bedtime.
Intravenous (Adults) Psychiatric interviews (unlabeled use)50–100 mg/min for total dose of 200–1000 mg or until patient experiences drowsiness, impaired attention, slurred speech, or nystagmus.
(Adults) Wada test (unlabeled use)100 mg over 4–5 sec via percutaneous transfemoral catheter.
Intramuscular Intravenous (Children 6–12 yr) Sedative–65–500 mg (3–5 mg/kg), depending on response.
Intramuscular (Children ≥6 yr) Hypnotic—2–3 mg/kg/dose.
Availability (generic available)
Injection: 500-mg vials
- Monitor respiratory status, pulse, and BP frequently.
- Prolonged therapy may lead to psychological or physical dependence. Restrict amount of drug available to patient, especially if depressed, suicidal, or with a history of addiction.
- Hypnotic: Assess sleep patterns before and periodically throughout therapy. Hypnotic doses of amobarbital suppress REM sleep. Patient may experience an increase in dreaming on discontinuation of medication. Monitor ambulation after administration.
Potential Nursing Diagnoses(Indications)
Risk for injury (Side Effects)
- Intramuscular: Intravenous: Reconstitute with sterile water for injection Rotate vial to mix; do not shake. Do not use if solution does not become absolutely clear within 5 min after reconstitution or if precipitate forms after the solution clears. Solution should be used within 30 min of reconstitution.
- Intramuscular: Do not administer subcut. Administer IM injections deep into gluteal muscle to minimize tissue irritation. IM doses should not exceed 500 mg or 5 mL.
- Intravenous: Diluent: May be further diluted in D5W, D10W, D20W, D5/0.9% NaCl, D5/LR, 0.9% NaCl, or LR. Concentration: Not to exceed of 100 mg/mL.
- Use the largest vein possible to prevent thrombosis. Solution is highly alkaline; avoid extravasation, which may cause tissue damage and necrosis. If extravasation occurs, infiltration of 5% procaine solution into affected area and application of moist heat may be ordered.
- Rate: Do not exceed the rate of 50 mg/min. Titrate slowly for desired response. Rapid administration may result in respiratory depression, apnea, laryngospasm, bronchospasm, or hypotension. Equipment for resuscitation should be readily available.
- Discuss the importance of preparing environment for sleep (dark room, quiet, avoidance of nicotine and caffeine).
- May cause daytime drowsiness. Caution patient to avoid driving and other activities requiring alertness until response to medication is known.
- Advise patient to make position changes slowly to minimize orthostatic hypotension.
- Caution patients to avoid taking alcohol or other CNS depressants concurrently with this medication.
- Advise patient to use a nonhormonal method of contraception while taking amobarbital and to notify health care professional promptly if pregnancy is planned or suspected.
- Instruct patient to contact health care professional immediately if sore throat, fever, mouth sores, unusual bleeding or bruising, or petechiae occur.
- Improvement in sleep pattern without excessive daytime sedation. May take 2 days for effects to become evident. Therapy is usually limited to a 2-wk period.