What is the recommended dose of Gardenal (phenobarbital) for seizure management?

Phenobarbital (Gardenal) Dosing for Seizure Management

For status epilepticus in adults, phenobarbital should be administered at 15-20 mg/kg IV over 10-15 minutes, with a maximum initial dose of 1000 mg. 1

Dosing Guidelines by Age Group and Indication

Adults

• Status epilepticus: 20-320 mg IV, may be repeated in 6 hours as necessary 1
  • Loading dose: 15-20 mg/kg IV over 10-15 minutes 1
  • Maximum initial dose: 1000 mg 2
• Maintenance therapy: 30-120 mg daily in 2-3 divided doses 1

Children

• Status epilepticus: 15-20 mg/kg IV over 10-15 minutes 2, 1
• Anticonvulsant therapy: 4-6 mg/kg/day for 7-10 days to achieve blood level of 10-15 mcg/mL 1
• Alternative dosing: 10-15 mg/kg/day IM or IV 1

Neonates

• Seizures: 10 mg/kg IV 2
• Maintenance therapy: 3-4 mg/kg/day 3

Administration Guidelines

Intravenous Administration

• Rate of administration: Should not exceed 60 mg/min for adults 1
• Site selection: Use larger veins; avoid small veins on dorsum of hand or wrist 1
• Monitoring: Continuous monitoring of vital signs, including blood pressure, respiration, and cardiac function is essential 1

Safety Precautions

• Equipment for resuscitation and artificial ventilation should be available during administration 1
• Avoid administration into varicose veins due to retarded circulation 1
• Careful technique, including aspiration, is necessary to avoid inadvertent intraarterial injection 1

Therapeutic Considerations

Therapeutic Levels

• Target blood level: 10-15 mcg/mL for anticonvulsant effect 1
• For partial seizures, higher plasma concentrations (approximately 37 mcg/mL) may be necessary compared to tonic-clonic seizures alone (18 mcg/mL) 4

Pharmacokinetics

• Long half-life (62-103 hours) allows for less frequent dosing but increases risk of accumulation 5
• In children with severe malaria and seizures, a loading dose of 15 mg/kg IV achieves plasma concentrations >15 mg/mL with good clinical effect 5

Special Considerations

Potential Adverse Effects

• Respiratory depression and hypotension due to vasodilatory and cardiodepressant effects 2
• Increased risk of respiratory depression when combined with other sedative agents 2
• Be prepared to provide respiratory support and monitor oxygen saturation 2

Efficacy Considerations

• In status epilepticus, phenobarbital has been shown to be equally efficacious compared to lorazepam, phenytoin, and phenytoin plus diazepam 2
• Status epilepticus duration may be shorter with phenobarbital use, with 61% of patients not requiring additional anticonvulsants 2

Cautions

• Parenteral routes should only be used when oral administration is impossible or impractical 1
• Intramuscular injections should be made deeply into a large muscle, with volume not exceeding 5 mL at any one site 1
• Injection into or near peripheral nerves may result in permanent neurological deficit 1

Remember that phenobarbital dosing must be individualized based on patient's age, weight, and clinical condition, with careful monitoring of therapeutic response and adverse effects.