Do I use "actual weight" or "ideal weight" to calculate dantrolene dosing?

MHAUS regularly receives inquiries regarding the appropriate first dose administration of dantrolene. 

Our recommendation is a starting dose of 2.5 mg/kg intravenously based upon the patient’s true weight rather than ideal weight. 

Although no scientific study has addressed the difference in this dosing recommendation, we believe the dosage based upon the patient’s true weight would achieve a more desirable concentration of dantrolene as it redistributes from the circulatory system to the intracellular tissue spaces of skeletal muscle where its major site of action is believed to occur. 

Following the initial dose administration, if symptoms are not improving, continuing to administer up to 10 mg/kg is also recommended.  This is not a ceiling dose, but just a guideline for initial administration. 

We recommend contacting the MH Hotline  during an emergency if further guidance or consultation may be helpful.