What is the drop rate per minute of phenobarbital for a 10 kg child?

Phenobarbital IV Drip Rate Calculation for 10 kg Child

For a 10 kg child requiring phenobarbital in 50 ml NS with a drop factor of 20 drops/ml, the appropriate drip rate is 33 drops per minute to deliver a loading dose of 20 mg/kg over 10-20 minutes.

Dosage Calculation

1. Determine the appropriate dose:

   • According to the American Academy of Pediatrics guideline, the loading dose for phenobarbital in status epilepticus is 20 mg/kg 1
   • For a 10 kg child: 20 mg/kg × 10 kg = 200 mg total dose

2. Infusion preparation:

   • Phenobarbital 200 mg in 50 ml NS
   • Concentration: 4 mg/ml (200 mg ÷ 50 ml)

3. Administration rate calculation:

   • Recommended infusion time: 10-20 minutes 1
   • Using 15 minutes as the target infusion time:
     • Volume to be infused: 50 ml
     • Rate: 50 ml ÷ 15 minutes = 3.33 ml/minute
   • With drop factor of 20 drops/ml:
     • 3.33 ml/minute × 20 drops/ml = 66.6 drops/minute
   • Rounded to 67 drops/minute

4. Safety adjustment:

   • To reduce risk of hypotension and respiratory depression, a slightly slower rate of 33 drops/minute (infusing over 30 minutes) is safer while still being therapeutically effective 1, 2

Clinical Considerations

• Monitoring requirements:

  • Continuous cardiorespiratory monitoring
  • Oxygen saturation monitoring
  • Blood pressure monitoring every 5 minutes during infusion
  • Respiratory support equipment should be immediately available

• Expected therapeutic levels:

  • Target serum concentration: 15-40 μg/ml 3
  • For refractory seizures, levels up to 100 μg/ml may be needed 3

• Potential adverse effects:

  • Respiratory depression (6-7.5% of cases) 1
  • Hypotension (especially with rapid infusion)
  • Prolonged sedation
  • Paradoxical reactions (rare)

Maintenance Dosing

After the loading dose, maintenance dosing should be:

• 3-4 mg/kg/day divided into 1-2 doses 3
• For continued status epilepticus, additional doses of 5-10 mg/kg may be given until seizures stop 1

Important Cautions

• Do not exceed infusion rate of 1 mg/kg/minute to minimize risk of hypotension 1
• Have resuscitation equipment readily available
• Phenobarbital has a long half-life (82-103 hours in children) 2, requiring careful monitoring for cumulative effects
• Consider alternative agents if seizures persist after reaching serum levels of 40 μg/ml

This dosing recommendation balances the need for rapid seizure control with safety considerations for this young patient.