• PO: Treatment of spasticity associated with:
  • Spinal cord injury,
  • Stroke,
  • Cerebral palsy,
  • Multiple sclerosis.
• Prevention of malignant hyperthermia in patients at high risk.
• IV: Emergency treatment of malignant hyperthermia.
• Prevention of malignant hyperthermia in patients at high risk.

Unlabeled Uses:

• Management of moderate to severe neuroleptic malignant syndrome.

Contraindicated in:

• Situations in which spasticity is used to maintain posture or balance (PO only)
• Lactation: Lactation.

Use Cautiously in:

• Cardiac, pulmonary, or previous liver disease
• Women and patients >35 yr (↑ risk of hepatotoxicity)
• OB: Use during pregnancy only if potential maternal benefit justifies potential fetal risk
• Geri: Use lowest possible dose in older adults (may have ↑ risk of hepatotoxicity).

CV: changes in BP, HF, tachycardia.

Derm: flushing, pruritus, sweating, urticaria.

EENT: excessive lacrimation, visual disturbances.

GI: diarrhea, anorexia, cramps, dysphagia, GI bleeding, HEPATOTOXICITY, nausea, vomiting.

GU: crystalluria, dysuria, erectile dysfunction, frequency, incontinence, nocturia.

Hemat: anemia, aplastic anemia, eosinophilia, leukopenia, thrombocytopenia.

Local: irritation at IV site, phlebitis.

MS: myalgia.

Neuro: drowsiness, muscle weakness, confusion, dizziness, headache, insomnia, malaise, nervousness.

Resp: dyspnea, pleural effusion, respiratory depression.
Misc: ANAPHYLAXIS, chills, drooling, fever.

Drug-Drug:

• Calcium channel blockers may ↑ risk of cardiovascular collapse; avoid concomitant use
• Additive CNS depression with CNS depressants, including alcohol, antihistamines, opioid analgesics, sedative/hypnotics, and parenteral magnesium sulfate.
• ↑risk of hepatotoxicity with other hepatotoxic agents or estrogens.
• ↑risk of arrhythmias with verapamil.
• ↑neuromuscular blocking effects of vecuronium.

Drug-Natural Products:

• Concomitant use of kava-kava, valerian, chamomile, or hops can ↑ CNS depression.

(Generic available)

• Capsules: 25 mg; 50 mg; 100 mg;
• Powder for injection: 20 mg/vial; 250 mg/vial;

Spasticity

• PO (Adults): 25 mg once daily for 7 days, then 25 mg 2 times daily for 7 days, then 50 mg 3 times daily for 7 days, then 100 mg 3 times daily; may ↑ to 100 mg 4 times daily, if needed.
• PO (Children 5 yr): 0.5 mg/kg once daily for 7 days, then 0.5 mg/kg 3 times daily for 7 days, then 1 mg/kg 3 times daily for 7 days, then 2 mg/kg 3 times daily (not to exceed 400 mg/day).

Prevention of Malignant Hyperthermia

• PO (Adults and Children 5 yr): 4–8 mg/kg/day in 3–4 divided doses for 1–2 days before procedure, with last dose 3–4 hr preoperatively.
• IV (Adults and Children): 2.5 mg/kg given 75 min before surgery.

Treatment of Malignant Hyperthermia

• IV (Adults and Children): At least 1 mg/kg, continued until symptoms ↓ or a cumulative dose of 10 mg/kg has been given. If symptoms reappear, dose may be repeated.

Neuroleptic Malignant Syndrome (unlabeled)

• IV (Adults): 1–2.5 mg/kg initially; if rapid resolution of hyperthermia and rigidity is observed, may follow with 1 mg/kg every 6 hours (max dose = 10 mg/kg/day). After the patient is stabilized and symptoms have resolved, consider taper over days to weeks (do not abruptly discontinue).

Dantrium, Revonto, Ryanodex

• Acts directly on skeletal muscle, causing relaxation by decreasing calcium release from sarcoplasmic reticulum in muscle cells.
• Prevents intense catabolic process associated with malignant hyperthermia.

• Reduction of muscle spasticity.
• Treatment and prevention of malignant hyperthermia.

Therapeutic Classification: skeletal muscle relaxants (direct acting)

Absorption: 35% absorbed after oral administration. IV administration results in complete bioavailability.

Distribution: Widely distributed to tissues.

Metabolism/Excretion: Almost entirely metabolized by the liver.

Half-life: 8.7–11.4 hr.

(effects on spasticity)

• Advise patient not to take more medication than the amount prescribed, to minimize risk of hepatotoxicity and other side effects. If a dose is missed, do not take unless remembered within 1 hr. Do not double doses.
  • May cause dizziness, drowsiness, visual disturbances, and muscle weakness. Advise patient to avoid driving and other activities requiring alertness until response to drug is known. After IV dose for surgery, patients may experience decreased grip strength, leg weakness, light-headedness, and difficulty swallowing for up to 48 hr. Caution patients to avoid activities requiring alertness and to use caution when walking down stairs and eating during this period.
  • Advise patient to avoid taking alcohol or other CNS depressants concurrently with this medication.
  • Instruct patient to notify health care professional if rash; itching; yellow eyes or skin; dark urine; or clay-colored, bloody, or black, tarry stools occur or if nausea, weakness, malaise, fatigue, or diarrhea persists. May require discontinuation of therapy.
  • Advise patient to wear sunscreen and protective clothing to prevent photosensitivity reactions.
  • Advise females of reproductive potential to notify health care professional if pregnancy is planned or suspected and to avoid breastfeeding during and for 3 days after last dose. Monitor infants breastfed during therapy for respiratory depression and muscle weakness.
  • Emphasize the importance of follow-up exams to check progress in long-term therapy and blood tests to monitor for side effects.
• Malignant Hyperthermia: Patients with malignant hyperthemia should carry identification describing disease process at all times.

DAN-troe-leen