How to prepare a labetalol infusion of 0.5 mg/min from a 5 mg/ml solution?

Preparation of Labetalol Infusion at 0.5 mg/min

To prepare a labetalol infusion of 0.5 mg/min using a 5 mg/ml solution (20 mg vial), dilute 60 mg (12 ml) of labetalol in 60 ml of compatible diluent (normal saline or D5W) and infuse at 30 ml/hour.

Calculation Method

1. Determine required dose rate: 0.5 mg/min = 30 mg/hour

2. Calculate concentration needed:

   • Using a standard infusion rate of 30 ml/hour (0.5 ml/min)
   • Required concentration: 30 mg/hour ÷ 30 ml/hour = 1 mg/ml

3. Prepare the solution:

   • Starting with 5 mg/ml labetalol solution
   • For a 1 mg/ml concentration: Dilute 60 mg (12 ml) of labetalol to a total volume of 60 ml
   • Add 48 ml of diluent (normal saline or D5W) to 12 ml of labetalol

Infusion Guidelines

According to clinical guidelines, labetalol infusion can be administered at various rates depending on the clinical situation:

• For hypertensive emergencies: 0.4-1.0 mg/kg/h IV infusion (approximately 0.5-3 mg/min) 1
• Standard maintenance infusion: 2-8 mg/min or 5-20 mg/hour 1
• For continuous infusion: 0.5-2.0 mg/min 2

Compatible Diluents

• Normal saline (0.9% sodium chloride)
• D5W (5% dextrose in water)

Monitoring Requirements

• Blood pressure monitoring every 15 minutes for the first 2 hours
• Then every 30 minutes for 6 hours
• Then hourly thereafter 1
• Target a 10-15% reduction in blood pressure in the first hour

Important Considerations

• Maximum dose: The maximum cumulative dose of labetalol is 300 mg 1
• Contraindications: History of 2nd or 3rd degree AV block, systolic heart failure, asthma, and bradycardia 1
• Common adverse effects: Bradycardia, bronchospasm, and hypotension 1
• Storage: Once diluted, the solution should be used within 24 hours

Alternative Preparation Method

If a different infusion rate is preferred, you can adjust the concentration accordingly:

• For 60 ml/hour infusion rate: Dilute 60 mg (12 ml) of labetalol to a total volume of 120 ml (0.5 mg/ml)
• For 15 ml/hour infusion rate: Dilute 60 mg (12 ml) of labetalol to a total volume of 30 ml (2 mg/ml)

Always verify the calculation and preparation with another healthcare provider before administration to ensure patient safety.