What is the recommended dose of dantrolene (Dantrium) for treating malignant hyperthermia?

Dantrolene Dosing for Malignant Hyperthermia

The recommended initial dose of dantrolene for treating malignant hyperthermia is 2-2.5 mg/kg based on actual body weight, with repeated doses every 10 minutes until symptoms subside or clinical goals are achieved. 1

Initial Treatment Protocol

Initial Dose

• Initial bolus: 2-2.5 mg/kg IV based on actual body weight (not ideal body weight) 1
• Maximum initial dose: 300 mg 1
• Administration: Rapid IV push 2

Subsequent Dosing

• Repeat 2-2.5 mg/kg every 10 minutes (or as soon as possible if preparation takes longer) 1
• Continue until signs of MH regress 1

Clinical Endpoints for Stopping Dantrolene Administration

• PaCO₂ < 6 kPa (with normal minute ventilation)
• Decreasing core body temperature 1

Important Clinical Considerations

Maximum Dose Considerations

• Recommended maximum cumulative dose: 10 mg/kg 2
• However, this maximum may need to be exceeded in fulminant MH reactions 1
• If 10 mg/kg is reached without symptom control, reassess diagnosis but continue dantrolene if MH is still suspected 1

Recrudescence Management

• Recrudescence occurs in approximately 10-15% of cases 1
• Higher risk in more severe initial reactions 1
• If recrudescence occurs, administer further doses of 2-2.5 mg/kg every 10 minutes until signs resolve 1
• If recrudescence occurs within 6 hours of initial reaction: use 1 mg/kg 1
• If recrudescence occurs more than 6 hours after initial reaction: use 2-3 mg/kg 1

Post-Crisis Management

• Oral dantrolene 4-8 mg/kg/day in four divided doses for 1-3 days following crisis 2
• When oral administration is not practical, individualized IV dosing starting at 1 mg/kg may be used 2

Special Considerations

Continuous Infusion

• Continuous infusion is not recommended after the initial loading dose 1
• Therapeutic plasma concentrations are maintained for ~6 hours after loading dose 1
• Continuous infusion is associated with high incidence of thrombophlebitis 1

Pediatric Dosing

• Same as adult dosing (2-2.5 mg/kg initially) 1, 2
• For children: initial 2-3 mg/kg with further boluses of 1 mg/kg every 5 minutes until treatment goals are achieved 1

Obese Patients

• Use actual body weight for dosing, not ideal body weight 1
• This is based on the lipophilic nature of dantrolene 1

Practical Implementation

• Each vial contains 20 mg dantrolene 1
• Reconstitute with 60 mL sterile water for injection 2
• Protect from direct light and use within 6 hours after reconstitution 2
• Do not use acidic solutions (like 5% Dextrose or 0.9% Sodium Chloride) for reconstitution 2

Remember that early administration of appropriate dantrolene doses is essential for successful treatment of malignant hyperthermia, with mortality reduced from >80% to <10% with proper treatment 3.