Dantrolene (RYANODEX) is an intravenous nanosuspension of dantrolene sodium used as a prophylactic and therapeutic agent to treat malignant hyperthermia (MH) – a life-threatening condition triggered by succinylcholine and halogenated volatile anesthetic gases creating sustained skeletal muscle contraction due to a defect in the release/reuptake of calcium. Dantrolene works by inhibiting calcium-induced calcium release from the sarcoplasmic reticulum/T-tubule network leading to skeletal muscle relaxation.

Compared to traditional dantrolene formulations, a vial of RYANODEX contains 250 mg of dantrolene (pictured) and requires only 5 cc of sterile water to reconstitute. Traditional vials contain ~ 20 mg of dantrolene per vial, and each requires > 50 cc of sterile water to constitute. In addition, the initial dose of dantrolene for MH is 2.5 mg/kg, so we’re saving a tremendous amount of time using RYANODEX… especially in an emergency like MH.

Although I have never encountered MH, having it on my radar as an anesthesiologist and intensivist is incredibly important as this condition is lethal without proper diagnosis and treatment!

Drop me a comment below with questions! 🙂

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  1. MH is a risk factor if the patient has had previous administration of Pholcodine – an OTC cough suppressant in some countries.

  2. As a GP, what are the main symptoms/signs to early detect MH? And what would be the bests initial manegement strategies (before anastesiologist consult)?


  3. Fabulous! You’re a life saver Dr. Rishi, thanks a lot brother. I’m happy to know about RYANODEX- It’ll save a lot of time right. God bless…


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