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Ryanodex Side Effects

Generic Name: dantrolene

Note: This page contains side effects data for the generic drug dantrolene. It is possible that some of the dosage forms included below may not apply to the brand name Ryanodex.

In Summary

Common side effects of Ryanodex include: drowsiness. See below for a comprehensive list of adverse effects.

For the Consumer

Applies to dantrolene: oral capsule

As well as its needed effects, dantrolene (the active ingredient contained in Ryanodex) may cause unwanted side effects that require medical attention. Serious side effects are very rare when dantrolene is taken for a short time, for example, when it is used for a few days before, during, or after surgery or anesthesia to prevent or treat malignant hyperthermia. However, serious side effects may occur, especially when the medicine is taken for a long time.

Major Side Effects

If any of the following side effects occur while taking dantrolene, check with your doctor immediately:

Less common:
  • Bloody or black, tarry stools
  • bloody or dark urine
  • bluish color changes in skin color
  • changes in speech
  • chest pain
  • confusion
  • constipation
  • convulsions (seizures)
  • decrease in frequency of urination
  • decrease in urine volume
  • difficult urination
  • difficulty in moving
  • difficulty in passing urine (dribbling)
  • difficulty in swallowing
  • fast, pounding, or irregular heartbeat or pulse
  • increased frequency of urination
  • increased urge to urinate during the night
  • joint pain
  • light-colored stools
  • lightheadedness
  • loss of bladder control
  • mental depression
  • muscle aching or cramping
  • muscle pains or stiffness
  • muscle spasm or jerking of all extremities
  • nausea and vomiting
  • pain in lower back
  • pain or burning while urinating
  • pain, tenderness, or changes in skin color
  • painful urination
  • severe stomach pain
  • shortness of breath
  • skin rash, hives, or itching
  • slow or troubled breathing
  • sudden decrease in amount of urine
  • sudden loss of consciousness
  • swelling of foot or leg
  • swollen joints
  • unusual tiredness or weakness
  • upper right abdominal pain
  • vomiting of blood or material that looks like coffee grounds
  • waking to urinate at night
  • yellow eyes or skin

Minor Side Effects

Some dantrolene side effects may not need any medical attention. As your body gets used to the medicine these side effects may disappear. Your health care professional may be able to help you prevent or reduce these side effects, but do check with them if any of the following side effects continue, or if you are concerned about them:

More common:
  • Diarrhea
  • dizziness
  • drowsiness
  • general feeling of discomfort or illness
  • muscle weakness
Less common:
  • Abdominal or stomach cramps or discomfort
  • abnormal hair growth
  • acne-like rash
  • blurred or double vision or any change in vision
  • change in taste
  • chills and fever
  • disturbed color perception
  • excessive tearing
  • halos around lights
  • headache
  • itching skin
  • loss of appetite
  • night blindness
  • overbright appearance of lights
  • redness of skin
  • seeing double
  • skin rash, encrusted, scaly and oozing
  • sleeplessness
  • slurring of speech or other speech problems
  • sudden decrease in amount of urine
  • sweating
  • trouble in sleeping
  • tunnel vision
  • unable to sleep
  • unusual nervousness
  • weight loss

For Healthcare Professionals

Applies to dantrolene: intravenous powder for injection, oral capsule

Nervous system

Nervous system side effects have commonly included drowsiness (30%), dizziness (14%), and malaise. Speech disturbances, headache, seizures and hallucinations have been reported less frequently.[Ref]

Gastrointestinal

Several reports of severe constipation and abdominal distention leading to functional obstruction have been reported.[Ref]

Gastrointestinal side effects have frequently included diarrhea which may be severe enough to require discontinuation. Constipation, abdominal cramps, nausea, and vomiting have been reported less frequently.[Ref]

Hematologic

Hematologic side effects have included aplastic anemia, leukopenia, and lymphocytic lymphoma.[Ref]

Musculoskeletal

Musculoskeletal side effects have commonly included weakness which is usually tolerable. Myalgia and backache have also been reported.[Ref]

Hepatic

Risk of hepatic injury is greater in females, patients over 35 years of age, and in patients on concurrent medications. The severity of the reaction appears to increase with increases in dose and duration.[Ref]

Hepatic side effects have included hepatic injury (1.8%), hepatitis (0.6%), and fatal hepatitis (0.3%).[Ref]

Respiratory

Respiratory side effects have infrequently included pulmonary edema with the use of intravenous dantrolene (the active ingredient contained in Ryanodex) Pleural effusion and pneumonitis have also been reported.[Ref]

Cardiovascular

Cardiovascular side effects have infrequently included pericarditis (both with and without pleural effusion) in patients receiving oral dantrolene (the active ingredient contained in Ryanodex) Cardiovascular side effects reported postmarketing have included heart failure.[Ref]

Local

Local side effects have included thrombophlebitis in patients receiving intravenous dantrolene (the active ingredient contained in Ryanodex) [Ref]

Dermatologic

Dermatologic side effects have included rare reports of acne.[Ref]

Ocular

Ocular side effects have included visual disturbances.[Ref]

Other

Other side effects have included one case of bilateral hearing loss which was thought to have been secondary to dantrolene (the active ingredient contained in Ryanodex) treatment.[Ref]

Hypersensitivity

Hypersensitivity side effects reported postmarketing have included anaphylaxis.

References

1. Andrews LG, Muzumdar AS, Pinkerton AC "Letter: Hallucinations associated with dantrolene sodium therapy." Can Med Assoc J 112 (1975): 148

2. Chyatte SB, Basmajian JV "Dantrolene sodium: long-term effects in severe spasticity." Arch Phys Med Rehabil 54 (1973): 311-5

3. "Product Information. Dantrium (dantrolene)." Procter and Gamble Pharmaceutic, Cincinnati, OH.

4. Dykes MH "Evaluation of a muscle relaxant: dantrolene sodium (Dantrium)." JAMA 231 (1975): 862-4

5. Allen GC, Cattran CB, Peterson RG, Lalande M "Plasma levels of dantrolene following oral administration in malignant hyperthermia-susceptible patients." Anesthesiology 69 (1988): 900-4

6. Chan CH "Dantrolene sodium and hepatic injury." Neurology 40 (1990): 1427-32

7. Shaivitz SA "Letter: Dantrolene." JAMA 229 (1974): 1282-3

8. Wilkinson SP, Portmann B, Williams R "Hepatitis from dantrolene sodium." Gut 20 (1979): 33-6

9. Utili R, Boitnott JK, Zimmerman HJ "Dantrolene-associated hepatic injury. Incidence and character." Gastroenterology 72 (1977): 610-6

10. Miller DH, Haas LF "Pneumonitis with dantrolene." J Neurol Neurosurg Psychiatry 47 (1984): 553-4

11. Petusevsky ML, Faling LJ, Rocklin RE, Snider GL, Merliss AD, Moses JM, Dorman SA "Pleuropericardial reaction to treatment with dantrolene." JAMA 242 (1979): 2772-4

12. Felz MW, HavilandFoley DJ "Eosinophilic pleural effusion due to dantrolene: Resolution with steroid therapy." South Med J 94 (2001): 502-4

13. Pembroke AC, Saxena SR, Kataria M, Zilkha KD "Acne induced by dantrolene." Br J Dermatol 104 (1981): 465-8

14. Pace-Balzan A, Ramsden RT "Sudden bilateral sensorineural hearing loss during treatment with dantrolene sodium (dantrium)." J Laryngol Otol 102 (1988): 57-8

It is possible that some side effects of Ryanodex may not have been reported. These can be reported to the FDA here. Always consult a healthcare professional for medical advice.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. Drugs.com does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.

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