pentobarbital

REMS

Hypnotic agent (short-term).
Preoperative sedation and other situations in which sedation is required.
Seizures.

Unlabeled Use:

IV: Induction of coma in selected patients with cerebral ischemia and management of increased intracranial pressure (high doses).

Action ⬆ ⬇

Depresses the CNS, probably by potentiating GABA, an inhibitory neurotransmitter.
Produces all levels of CNS depression, including the sensory cortex, motor activity, and altered cerebellar function.
Anticonvulsant effect due to decreased synaptic transmission and increased seizure threshold.
May decrease cerebral blood flow, cerebral edema, and intracranial pressure (IV only).

Therapeutic effects:

Sedation and/or induction of sleep.

Pharmacokinetics ⬆ ⬇

Absorption: IV administration results in complete bioavailability.

Distribution: Widely distributed; highest concentrations in brain and liver. Crosses the placenta; small amounts enter breast milk.

Metabolism/Excretion: Metabolized by the liver. Minimal renal excretion.

Half-Life: Children: 25 hr; Adults: 35–50 hr.

Time/Action Profile ⬆ ⬇

(sedation)

ROUTE	ONSET	PEAK	DURATION‡
IM	10–25 min	unknown	1–4 hr
IV	immediate	1 min	15 min

‡Noted as hypnotic effect; sedative effects are longer lasting.

Contraind./Precautions ⬆ ⬇

Contraindicated in:

Hypersensitivity;
Contains alcohol and propylene glycol and should be avoided in patients with known hypersensitivity or intolerance;
Comatose patients or those with pre-existing CNS depression (unless used to induce coma);
Uncontrolled severe pain;
OB: Pregnancy (may affect child's brain development when used during 3rd trimester);
Lactation: Lactation.

Use Cautiously in:

Severe renal impairment;
Hepatic impairment;
Patients who may be suicidal or who may have been addicted to drugs previously;
Hypovolemic shock;
Pedi: Children 3 yr (may affect brain development);
Geri: Older adults at risk of falls (initial dose recommended).

Adv. Reactions/Side Effects ⬆ ⬇

CV: hypotension

Derm: rash, urticaria

GI: constipation, diarrhea, nausea, vomiting

Local: phlebitis

MS: arthralgia, myalgia, neuralgia

Neuro: drowsiness, hangover, lethargy, delirium, depression, excitation, vertigo

Resp: bronchospasm, LARYNGOSPASM, respiratory depression

Misc: HYPERSENSITIVITY REACTIONS (INCLUDING ANGIOEDEMA AND SERUM SICKNESS) , physical dependence, psychological dependence

Interactions ⬆ ⬇

Drug-drug:

Additive CNS depression with other CNS depressants, including alcohol, antihistamines, opioids, and other sedative/hypnotics.
May ↓ levels and effectiveness of oral contraceptives, warfarin, carbamazepine,chloramphenicol, cyclosporine, dacarbazine, doxycycline, corticosteroids, tricyclic antidepressants, and quinidine.
May ↑ risk of hepatic toxicity of acetaminophen.
MAO inhibitors, valproic acid, or divalproex may ↑ levels and ↑ sedation.

Drug-Natural Products:

Concomitant use of kava, valerian, skullcap, chamomile, or hops can ↑ CNS depression.
St. John's wort may ↓ levels and effectiveness.

Route/Dosage ⬆ ⬇

IM (Adults ): Hypnotic/preoperative sedative: 150–200 mg.
IM (Children ): Sedative: 2–6 mg/kg/day in divided doses. Preoperative sedative: 2–6 mg/kg (up to 100 mg/dose).
IV (Adults ): Hypnotic/anticonvulsant: 100 mg initially; additional small doses may be given every min up to 500 mg total. Induction of coma: 5–7 mg/kg, then 3–4 mg/kg every 3–4 hr dose adjusted by serum level (unlabeled).
IV (Children ): Sedative: 1–3 mg/kg to a maximum of 100 mg until asleep.Conscious sedation: Initial 2 mg/kg, may repeat every 5–10 min with 1–2 mg/kg until adequate sedation achieved. Maximum total dose 6 mg/kg or 150–200 mg.Induction of coma: 10–15 mg/kg slowly over 1–2 hr, followed by a maintenance infusion of 1–3 mg/kg/hr.

Availability ⬆ ⬇

(Generic available)

Solution for injection: 50 mg/mL

Assessment ⬆ ⬇

Monitor respiratory status, pulse, and BP frequently in patients receiving pentobarbital IV. Equipment for resuscitation and artificial ventilation should be readily available. Respiratory depression is dose dependent.
- Prolonged therapy may lead to psychological or physical dependence. Restrict amount of drug available to patient, especially if depressed, suicidal, or previously addicted.
- Assess postoperative patients for pain. Pentobarbital may increase responsiveness to painful stimuli.
- Therapeutic ranges: Sedation 1–5 mcg/mL; Sleep: 5–15 mcg/mL; Coma: 20–40 mcg/mL.
Sleep: Assess sleep patterns prior to and periodically during therapy. Hypnotic doses of pentobarbital suppress REM sleep. Patient may experience an increase in dreaming upon discontinuation of medication.
Cerebral Edema: Monitor intracranial pressure and level of consciousness in patients in barbiturate coma.
Seizures: Assess location, duration, and characteristics of seizure activity. Implement seizure precautions.

Implementation ⬆ ⬇

Do not confuse pentobarbital with phenobarbital.
- Supervise ambulation and transfer of patients following administration. Remove cigarettes. Side rails should be raised and call bell within reach at all times. Keep bed in low position.
IM: Do not administer SUBQ. Administer IM injections deep into the gluteal muscle to minimize tissue irritation. Do not inject more than 5 mL into any one site because of tissue irritation.

IV Administration:

Diluent: Doses may be given undiluted or diluted with sterile water, 0.45% NaCl, 0.9% NaCl, D5W, D10W, Ringer’s or LR, dextrose/saline combinations, or dextrose/Ringer’s or lactated Ringer’s combinations. Do not use solution that is discolored or that contains particulate matter.
- 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 used.
Rate: Administer each 50 mg over at least 1 min. Titrate slowly for desired response. Rapid administration may result in respiratory depression, apnea, laryngospasm, bronchospasm, or hypertension.

Patient/Family Teaching ⬆ ⬇

Explain purpose of pentobarbital to patient and family.
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.
Caution patient to avoid taking alcohol or other CNS depressants concurrently with this medication.
Rep: Advise females of reproductive potential to notify health care professional if pregnancy is planned or suspected or if breastfeeding.

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Pronunciation ⬇

Classifications ⬆ ⬇

Indications ⬆ ⬇