What is the standard dosing for Dantrolene (Dantrium)?

Standard Dosing for Dantrolene (Dantrium)

The standard initial dose of dantrolene for treatment of malignant hyperthermia (MH) is 2-2.5 mg/kg based on actual body weight, administered intravenously, with repeated doses every 10 minutes until symptoms subside or a maximum cumulative dose of 10 mg/kg is reached. 1

Acute Treatment of Malignant Hyperthermia

Initial Dosing

• Initial IV dose: 2-2.5 mg/kg based on actual body weight 1
• Administration: Rapid IV push 2
• For adults: Each syringe should be administered as soon as it is prepared rather than waiting for the complete initial dose to be ready 1
• For children: Initial 2-3 mg/kg followed by boluses of 1 mg/kg every 5 minutes until treatment goals are achieved 1

Subsequent Dosing

• Repeat initial dose every 10 minutes (or as soon as possible if administration takes >10 minutes) until signs of MH regress 1
• Continue until treatment goals are achieved: 1
  • PaCO₂ < 6 kPa with normal minute ventilation
  • Core temperature < 38.5°C

Maximum Dosing

• Recommended maximum dose is 10 mg/kg 2
• However, this maximum dose may need to be exceeded in cases of fulminant MH if symptoms persist 1
• If cumulative dose of 10 mg/kg has been administered, guidelines recommend formal reappraisal of the diagnosis 1

Management of Recrudescence

• Recrudescence (recurrence of MH symptoms) may occur in up to 20% of cases, particularly in more severe cases 1
• If recrudescence occurs, administer further doses of dantrolene 2-2.5 mg/kg every 10 minutes until signs regress 1
• If recrudescence occurs within 6 hours of initial treatment: give 1 mg/kg 1
• If recrudescence occurs more than 6 hours after initial treatment: give 2-3 mg/kg 1

Important Considerations

Body Weight Calculation

• Dosing should be based on actual body weight, not ideal body weight 1
• Maximum initial dose should not exceed 300 mg 1

Continuous Infusion

• Continuous infusion of dantrolene is NOT recommended routinely after the initial loading dose 1
• Continuous infusion is associated with high incidence of thrombophlebitis due to high osmolarity of the solution 1
• After loading dose, therapeutic plasma concentrations are maintained for approximately 6 hours 1

Prophylactic Use

• For patients judged MH susceptible, prophylactic dose is 2.5 mg/kg IV starting approximately 1.25 hours before anticipated anesthesia, infused over 1 hour 2
• Oral prophylaxis: 4-8 mg/kg/day in 3-4 divided doses for 1-2 days prior to surgery, with last dose given 3-4 hours before surgery 2

Post-Crisis Follow-Up

• Oral dantrolene 4-8 mg/kg/day in four divided doses should be administered for 1-3 days following an MH crisis to prevent recurrence 2
• IV dantrolene may be used postoperatively when oral administration is not practical, starting with 1 mg/kg or more as clinically indicated 2

Preparation and Administration

• Each vial of dantrolene (20 mg) must be reconstituted with 60 mL of sterile water for injection 2
• The traditional formulation requires vigorous shaking for up to 5 minutes to dissolve 1
• A newer formulation (Ryanodex®) contains 250 mg per vial and can be rapidly dissolved in 5 mL of water (available in USA but not in UK/Europe) 1
• Reconstituted solution must be protected from direct light and used within 6 hours 2
• 5% Dextrose Injection, 0.9% Sodium Chloride Injection, and other acidic solutions are not compatible with dantrolene 2