Frequently Asked Questions

  • RYANODEX® is approved for the treatment of malignant hyperthermia (MH) in conjunction with appropriate supportive measures, and for the prevention of malignant hyperthermia in patients at high risk7
  • MH is a potentially fatal disorder triggered when susceptible individuals come in contact with certain volatile anesthetics and/or the paralytic succinylcholine10
  • RYANODEX® is supplied as 250 mg vials of dantrolene sodium in lyophilized powder form. It is reconstituted with 5 mL of sterile water for injection (non-bacteriostatic). Its formulation allows for reconstitution and administration in less than 1 minute to patients experiencing MH1,7
  • Upon reconstitution, RYANODEX® is a suspension of dantrolene sodium which should be administered by intravenous push7
  • The MHAUS recommended loading dose is 2.5 mg/kg. If MH symptoms continue, additional doses should be administered7,8

Dantrolene sodium is the standard of care for malignant hyperthermia (MH) treatment, and since 1979, has been one of the only pharmacotherapies available to reverse an MH episode.17 The following chart provides an overview of the primary differences between RYANODEX® (dantrolene sodium) for injectable suspension and other dantrolene sodium IV products:

Attribute Other dantrolene
sodium products1,4-6,8
Vials required
  • 1 vial contains 20 mg of dantrolene sodium
  • 1 vial contains 250 mg of dantrolene sodium
Time to reconstitute
  • More than 22 minutes to reconstitute and administer 13 vials
  • Less than 1 minute to reconstitute and administer 1 vial
Sterile water for injection
  • 60 mL per vial (750 mL for 250 mg of dantrolene sodium)
  • 1 mL contains 0.33 mg dantrolene sodium as a solution
  • 5 mL sterile water for injection (non-bacteriostatic)
  • 1 mL contains 50 mg dantrolene sodium as a uniform nanoparticle suspension*
Amount of mannitol
  • 3000 mg mannitol/vial (39,000 mg for 13 vials of older dantrolene sodium products)
  • 125 mg mannitol/vial

*RYANODEX® (upon reconstitution) is a uniform suspension of dantrolene sodium. Dissolution is extremely rapid in whole blood/plasma.4,7

Administration to conscious subjects is associated with flushing, somnolence, dysphonia, dysphagia, nausea.7

Each vial of RYANODEX® (dantrolene sodium) for injectable suspension contains only 125 mg of mannitol (the amount of mannitol in RYANODEX® is insufficient to maintain diuresis) compared with 3000 mg of mannitol in each vial of other dantrolene sodium for injection products.5-7

Other formulations of dantrolene sodium for injection are a lyophilized (dry), fluffy, light orange powder. RYANODEX® (dantrolene sodium) for injectable suspension differs from this in that it is a deep orange lyophilized (dry) cake with a lightened meniscus edge.1

Attribute RYANODEX®
Dry Reconstituted
Color Deep orange with a lightened meniscus edge Opaque bright orange
Texture Cake Nanoparticle suspension
Lyophilized Yes N/A
Attribute Other Dantrolene Sodium Products
Dry Reconstituted
Color Light orange Translucent light yellow/orange
Texture Fluffy Solution
Lyophilized Yes N/A

MHAUS recommends stocking a minimum of 700 mg dantrolene sodium, which is supplied in only 3 vials of RYANODEX® (dantrolene sodium) for injectable suspension (in contrast to the 36 vials required to obtain 700 mg with other dantrolene sodium IV products).18

Data suggest that the average patient uses a median dose of 5.9 mg/kg of dantrolene sodium in a crisis. For many patients, this is less than the recommended 700 mg. Check with your accrediting body and for additional information.14

RYANODEX® (dantrolene sodium) for injectable suspension has a shelf life of 33 months from the date of manufacture.1 There may be a time gap between the manufacturing date and the date of your order. To ensure accurate information about the shelf life, it is recommended to inquire directly with the supplier when placing an order for the product.

RYANODEX® (dantrolene sodium) for injectable suspension should be reconstituted with 5 mL sterile water for injection (without a bacteriostatic agent). Shake the vial until RYANODEX® is mixed thoroughly (should take less than 10 seconds). Suspension should be a uniform orange suspension. Please refer to the Reconstitution and Administration Instructions section (2.4) of the Prescribing Information.1,7

Reconstituted RYANODEX® (dantrolene sodium) for injectable suspension should be used within 6 hours after reconstitution. Store reconstituted suspension at controlled room temperature 20°C to 25°C (68°F to 77°F). Protect from light.7

RYANODEX® (dantrolene sodium) for injectable suspension should be reordered as soon as possible after use or about 1 to 2 months before expiration. Similar to other dantrolene sodium IV products, RYANODEX® cannot be returned for credit. Expired product should be discarded.

Eagle has developed a reconstitution and administration video, a reconstitution and administration dosing card, and other informational tools to educate medical practitioners on how to use RYANODEX® (dantrolene sodium) for injectable suspension. Go to for more information.

Store unreconstituted product at 20°C to 25°C (68°F to 77°F) [see United States Pharmacopeia (USP) Controlled Room Temperature] and avoid prolonged exposure to light.7

Malignant hyperthermia (MH) is a hypermetabolic condition that can be triggered when genetically susceptible individuals come in contact with certain inhaled (volatile) anesthetics or the muscle relaxant succinylcholine.10

Symptoms of MH include unexplained elevation of end-tidal carbon dioxide, muscle rigidity, tachycardia, acidosis, hyperthermia, hyperkalemia, skin mottling, sweating, ventricular tachycardia, cola-colored urine, ventricular fibrillation, and cyanosis. If not treated immediately, MH can be fatal.14

For more information on MH, visit the MHAUS website:

The general signs of malignant hyperthermia (MH) include elevated end tidal CO2, muscle rigidity, tachycardia, elevated body temperature, acidosis, rhabdomyolysis, hyperthermia, and hyperkalemia. Other clinical signs include skin mottling, sweating, ventricular tachycardia, cola-colored urine, ventricular fibrillation, and cyanosis.10,14

Incidences of MH during anesthesia procedures are estimated at 1 in 10,000 children compared with 1 in 50,000 for adults.10

Susceptibility to malignant hyperthermia (MH) is a genetically inherited condition where, upon exposure to triggering agents (volatile anesthetics and/or succinylcholine), a hypermetabolic condition results.10

Dantrolene sodium is the only known antidote for malignant hyperthermia (MH) induced by inhalational anesthetics in humans and is recognized as the only standard treatment for MH. The use of RYANODEX® (dantrolene sodium) for injectable suspension in the management of MH crises is not a substitute for previously known supportive measures. These measures must be individualized, but it will usually be necessary to discontinue the suspect triggering agents, attend to increased oxygen requirements, manage the metabolic acidosis, institute cooling when necessary, monitor urinary output, and monitor for electrolyte imbalance. Patients who receive IV dantrolene sodium preoperatively should have vital signs monitored.7,8

For more information about dantrolene, visit the dantrolene page on the MHAUS website.

  • For additional information, please refer to the full Prescribing Information
  • For additional background information on malignant hyperthermia, please visit
    • During an MH crisis, additional advice can be obtained by calling 800.MH.HYPER (800.644.9737)
  • To report a RYANODEX® related adverse event, or for other information on RYANODEX®, please contact Eagle Customer Service Team: 855.318.2170

Indication and Important Safety Information