Dantrolene Sodium: Primary Uses and Applications
Dantrolene sodium is primarily used for the management of malignant hyperthermia crises, a life-threatening genetic sensitivity of skeletal muscles to volatile anesthetics and depolarizing neuromuscular blocking drugs. 1, 2
Primary Indication: Malignant Hyperthermia
Mechanism of Action
- Inhibits excessive calcium release from the sarcoplasmic reticulum in skeletal muscle
- Acts as a specific antidote to malignant hyperthermia by directly affecting calcium flux 1, 3
- Binds to the ryanodine receptor, the major calcium release channel in skeletal muscle 4
Dosing for Malignant Hyperthermia
- Initial dose: 2-2.5 mg/kg based on actual body weight (maximum initial dose 300 mg) 1, 5
- Administration: Rapid intravenous push as soon as MH is recognized 2
- Each syringe should be administered immediately after reconstitution 1
- Follow-up doses: 1 mg/kg every 5-10 minutes until symptoms resolve 5
- Maximum cumulative dose typically 10 mg/kg, but may be exceeded if necessary 1, 5
Treatment Targets
- Reduction of ETCO₂ to less than 6 kPa with normal minute ventilation
- Core temperature < 38.5°C
- Stabilization of heart rate
- Resolution of muscle rigidity 1, 5
Prophylactic Use
- Indicated preoperatively to prevent malignant hyperthermia in susceptible individuals 2
- Sometimes used postoperatively to prevent recurrence 2
Secondary Indications
Neuroleptic Malignant Syndrome (NMS)
- Effective for treating NMS due to similar pathophysiology to malignant hyperthermia 3, 6
- Typical dosage for NMS: approximately 1 mg/kg per day 6
- Treatment duration averages 8-10 days, longer in cases with disturbance of consciousness 6
Muscle Spasticity
- Used in chronic disorders characterized by skeletal muscle spasticity 7
- Conditions include:
- Spinal cord injury
- Stroke
- Cerebral palsy
- Multiple sclerosis 7
- Acts directly on the contractile mechanism of skeletal muscle 7
- Less effective in multiple sclerosis compared to other causes of spasticity 7
Important Considerations
Availability Requirements
- Must be available wherever volatile anesthetics or succinylcholine are used 1
- Recommended stock: 36 vials immediately available with additional 24 vials accessible within 1 hour 1
Side Effects and Cautions
- Hepatic toxicity with long-term use (0.1-0.2% risk of fatal hepatitis) 7
- Muscle weakness (particularly concerning in ambulatory patients) 7
- Thrombophlebitis with continuous infusion 5
- Other common side effects: drowsiness, dizziness, visual symptoms, fatigue 5, 7
Formulation Challenges
- Poor water solubility makes rapid preparation difficult in emergencies 4
- Traditional formulation: 20 mg vials requiring 60 ml of sterile water and vigorous shaking 1
- Newer preparation (Ryanodex): 250 mg vial that dissolves in 5 ml water (not available in all countries) 1
Dantrolene sodium represents a critical life-saving medication that has reduced malignant hyperthermia mortality from approximately 80% to less than 10% since its introduction 4. Its primary use remains in the management of malignant hyperthermia crises, with secondary applications in treating neuroleptic malignant syndrome and muscle spasticity.