An antidote to malignant hyperthermia that promises to allow one person to prepare a much more concentrated dose of dantrolene in as little as one minute has been approved by the FDA.

A single vial of Ryanodex contains 250mg of dantrolene sodium in lyophilized powder form. It can be reconstituted with just 5mL of sterile water, thanks to what the company calls nanosuspension technology. The FDA fast-tracked approval under priority review after designating Ryanodex as an orphan drug — one developed specifically to treat a rare medical condition — in 2013.

Alternative approaches for addressing MH emergencies have typically involved reconstituting numerous 20mg vials of dantrolene, using much larger volumes of sterile water. Though recent improvements have allowed each vial to be reconstituted quickly, generating a large enough volume to treat an average-sized adult is likely to require several contributors.

"You have to recruit an army of people to reconstitute and administer the (alternative) product," says Steven Brill, Ph.D, chief scientific officer for Eagle Pharmaceuticals, which developed the new product. "The experts say that every minute counts (in an MH emergency), that the longer it takes to get it under control, the more problems you're likely to have. The beauty of Ryanodex is that everything can be accomplished pretty rapidly."

Dianne Daugherty, executive director of the Malignant Hyperthermia Association of the United States, says her organization is planning to do its own research on Ryanodex. "The only thing we know right now is that it's been approved," she said.

Ryanodex is available for order this month and will begin shipping shortly thereafter, says the company.

Accredited hospitals and surgery centers where triggering agents are used must have established treatment protocols for MH, including the use of dantrolene, according to standards of both The Joint Commission and the Accrediting Association for Ambulatory Health Care.

Jim Burger