Dantrolene
Common Brand Names: Dantrium
Therapeutic Class: Skeletal Muscle Relaxant
Common Injectable Dosage Forms:
Powder for Reconstitution: 20 mg in vials
Dosage Ranges:
For the treatment of spasticity associated with spinal cord injury, stroke, cerebral palsy, or multiple sclerosis: Normal dosage is 2.5-5 mg/kg approximately 1.25 hours prior to anesthesia and infused over 1 hour. May repeat dose up to accumulated dose of 10 mg/kg.
Administration and Stability: Reconstitute with 50 mL Sterile Water for Injection and use within 6 hours. Avoid use of glass bottles. Emergency or therapeutic dose may be given over rapid continuous IV push. Follow up doses given over 2-3 minutes.
Pharmacology/Pharmacokinetics: Dantrolene acts directly on skeletal muscle by interfering with release of calcium ions from the sarcoplasmic reticulum. It prevents or reduces the increase in mycoplasma calcium ion catabolic processes. Elimination half-life is 8.7 hours. Excretion is via feces (45-50%) and urine (25% as unchanged drug and metabolites).
Drug and Lab Interactions: Dantrolene is a major substrate of CYP3A4. Estrogens, CNS depressants, MAOIs, phenothiazines, verapamil, warfarin, azole antifungals, isoniazid, protease inhibitors, carbamazepine, phenobarbital, phenytoin, valerian root, St. John’s Wort, Kava Kava.
Contraindications/Precautions: Contraindicated in patients with active hepatic disease and where spasticity is used to maintain posture or balance. Use with caution in those with impaired cardiac function or impaired pulmonary function. Black box warning for hepatotoxicity. Pregnancy Category C.
Monitoring Parameters: Motor performance, nausea and vomiting, LFTs, cardiac monitoring, and blood pressure.
Adverse Effects: Possible adverse effects include drowsiness, dizziness, rash, diarrhea, vomiting, muscle weakness, blurred vision, and respiratory depression.
Common Clinical Applications: Primarily used for the treatment of spasticity associated with spinal cord injury, stroke, cerebral palsy, or MS. Also used for the treatment of malignant hyperthermia.
