Phenobarbital Dosage

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Usual Adult Dose for:

Usual Pediatric Dose for:

Additional dosage information:

Usual Adult Dose for Sedation

Oral, IV, or IM: 30 to 120 mg/day orally in 2 to 3 divided doses.
Maximum of 400 mg/day.
Preoperative sedation: 100 to 200 mg IM 60 to 90 minutes before surgery.

Usual Adult Dose for Insomnia

Oral: 100 to 200 mg with a maximum of 400 mg/day.
IM or IV: 100 to 320 mg with a maximum duration of 2 weeks.

Usual Adult Dose for Seizures

Status Epilepticus:
Loading dose IV: 10-20 mg/kg; may repeat dose in 20-minute intervals as needed (maximum total dose: 30 mg/kg)

Anticonvulsant Maintenance dose: Oral or IV
(Note: Maintenance dose usually starts 12 hours after loading dose):
1 to 3 mg/kg/day in 1 to 2 divided doses

Usual Pediatric Dose for Seizures

Status Epilepticus:
Loading dose IV:
Neonatal:15 to 20 mg/kg in a single or divided dose; may repeat doses of 5 to 10 mg/kg every 15 to 20 minutes as needed (maximum total dose: 40 mg/kg). Note: Additional respiratory support may be required, especially when maximizing loading dose.

Maintenance dose: Oral, IV: 3 to 4 mg/kg/day given once daily; maintenance dose usually starts 12 hours after loading dose; assess serum concentrations; increase to 5 mg/kg/day if needed (usually by second week of therapy).

Neonatal abstinence syndrome:
Loading dose (optional):
IV: 16 mg/kg as a single dose; follow with maintenance dose 12 to 24 hours after loading dose or:
Oral: 16 mg/kg divided into 2 doses and administered every 4 to 6 hours; follow with maintenance dose 12 to 24 hours after loading dose.

Maintenance dose: Oral or IV: Initial: 5 mg/kg/day divided every 12 hours; adjust dose according to abstinence scores and serum concentrations; usual required dose: 2 to 8 mg/kg/day. After patient is stabilized, decrease phenobarbital dose such that drug concentration decreases by 10% to 20% per day.

Neuroprotectant following anoxic injury (with or without cooling): IV: 40 mg/kg once; if introducing therapeutic hypothermia, administer prior to cooling.

Status epilepticus:
Loading dose: IV:
Infants and Children: Initial: 15 to 20 mg/kg (maximum: 1000 mg/dose); may repeat dose after 15 minutes as needed (maximum total dose: 40 mg/kg). Note: Additional respiratory support may be required, especially when maximizing loading dose.

Anticonvulsant maintenance dose: Oral, IV: Note: Maintenance dose usually starts 12 hours after loading dose:
Infants: 5 to 6 mg/kg/day in 1 to 2 divided doses
Children:
1 to 5 years: 6 to 8 mg/kg/day in 1 to 2 divided doses
5 to 12 years: 4 to 6 mg/kg/day in 1 to 2 divided doses
Adolescents 12 years or older: 1 to 3 mg/kg/day in 1 to 2 divided doses

Usual Pediatric Dose for Sedation

Children:
Sedation: Oral: 2 mg/kg/dose 3 times a day
Preoperative sedation: Oral, IM, or IV: 1 to 3 mg/kg 1 to 1.5 hours before procedure

Usual Pediatric Dose for Insomnia

Children:
Hypnotic: IM or IV: 3 to 5 mg/kg at bedtime

Usual Pediatric Dose for Hyperbilirubinemia

Less than 12 years: 3 to 8 mg/kg/day orally in 2 to 3 divided doses.
Maximum Dose: 12 mg/kg/day

Renal Dose Adjustments

The dosage should be reduced for patients with impaired renal function.

Liver Dose Adjustments

The dosage should be reduced for patients with hepatic disease.

Dose Adjustments

The dosage should be reduced in the elderly or debilitated because these patients may be more sensitive to barbiturates.

Precautions

Be prepared to support respiration, especially when maximizing loading dose.

Dialysis

Data not available

Other Comments

Clinical laboratory reference values should be used to determine the therapeutic anticonvulsant level of phenobarbital in the serum. To achieve the blood levels considered therapeutic in children, higher per kg doses are generally necessary.

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