How do I prepare a midazolam (Benzodiazepine) infusion?

Midazolam Infusion Preparation Guide

To prepare a midazolam infusion, dilute midazolam 5 mg/mL to a concentration of 0.5 mg/mL with 0.9% sodium chloride or 5% dextrose in water. 1

Standard Preparation Method

1. Gather supplies:

   • Midazolam ampoules (5 mg/mL)
   • Compatible diluent (0.9% sodium chloride or 5% dextrose in water)
   • Appropriate infusion syringe/bag
   • Sterile syringes and needles for drawing up medication

2. Calculate required concentration:

   • Standard dilution: 0.5 mg/mL (as recommended by FDA labeling) 1
   • Example: To prepare 50 mL of 0.5 mg/mL solution:
     • Draw up 5 mL of midazolam (5 mg/mL = 25 mg total)
     • Add 45 mL of diluent
     • Final concentration: 25 mg in 50 mL = 0.5 mg/mL

3. Dosing guidelines for continuous infusion:

   • Initial loading dose (if needed): 0.01-0.05 mg/kg (approximately 0.5-4 mg for typical adult)
   • Maintenance infusion: 0.02-0.10 mg/kg/hr (1-7 mg/hr for typical adult) 1
   • Titrate to desired sedation level by adjusting rate up or down by 25-50% of initial rate

Special Considerations

• ICU sedation: Studies show effective plasma concentrations around 163-215 ng/mL, typically achieved with infusion rates of 0.06 mg/kg/hr 2

• Dose adjustments:

  • Reduce dose by 20% or more in patients over 60 years or ASA III or greater 3
  • Use lower doses in patients with residual effects from anesthetic drugs or those receiving other sedatives/opioids 1
  • For patients with hepatic or renal impairment, reduce dose due to decreased clearance 3

• Monitoring:

  • Assess sedation at regular intervals
  • Monitor oxygen saturation and respiratory status continuously
  • Be prepared to provide respiratory support
  • Have flumazenil available to reverse life-threatening respiratory depression 3

Titration Protocol

1. Initial titration:

   • Start with recommended initial rate
   • Assess sedation level every 10-15 minutes initially
   • Adjust rate up or down by 25-50% based on response 1

2. Maintenance adjustment:

   • Decrease rate by 10-25% every few hours to find minimum effective dose
   • This minimizes drug accumulation and provides faster recovery 1

3. For inadequate sedation:

   • Consider bolus dose equal to or double the hourly infusion rate
   • If two bolus doses are required within an hour, double the infusion rate 3

Common Pitfalls and Cautions

• Respiratory depression: Major side effect of midazolam, especially when combined with opioids. Deaths have been reported. 3

• Prolonged sedation: Can occur due to altered kinetics in critically ill patients or accumulation of active metabolites 4

• Withdrawal syndrome: Avoid sudden discontinuation after prolonged use. Taper over several days if used for extended periods 5

• Drug interactions: Bioavailability increased by approximately 30% in patients using H2-receptor antagonists 3

• Compatibility: Midazolam can be mixed in the same syringe as diamorphine for subcutaneous infusions 6

By following these guidelines, you can safely prepare and administer midazolam infusions while minimizing risks of complications and optimizing patient outcomes.