dantrolene (dan-troe-leen) Dantrium, Ryanodex

 Indications

PO: Treatment of spasticity associated with: Spinal cord

injury, stroke, cerebral palsy, multiple sclerosis. Prophylaxis

of malignant hyperthermia. IV: Emergency

treatment of malignant hyperthermia. Prevention of malignant

hyperthermia in patients at high risk. Unlabeled

Use: Management of neuroleptic malignant

syndrome.

Action

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. Therapeutic

Effects: Reduction of muscle spasticity. Treatment

and prevention of malignant hyperthermia.

Pharmacokinetics

Absorption: 35% absorbed after oral administration.

IV administration results in complete bioavailability.

Distribution: Unknown.

Metabolism and Excretion: Almost entirely metabolized

by the liver.

Half-life: 8.7–11.4 hr.

TIME/ACTION PROFILE (effects on spasticity)

ROUTE ONSET PEAK DURATION

PO 1 wk unknown 6–12 hr

IV rapid rapid unknown

Contraindications/Precautions

Contraindicated in: No contraindications to IV

form in treatment of malignant hyperthermia; Lactation:

Lactation; Situations in which spasticity is used to maintain

posture or balance.

Use Cautiously in: Cardiac, pulmonary, or previous

liver disease; Women and patients 35 yr (qrisk of

hepatotoxicity); Geri: Use lowest possible dose (may

haveqrisk of hepatotoxicity); OB: Use only if benefit

outweighs potential risk to fetus.

Adverse Reactions/Side Effects

CNS: drowsiness, muscle weakness, confusion, dizziness,

headache, insomnia, malaise, nervousness.

EENT: excessive lacrimation, visual disturbances.

Resp: dyspnea, pleural effusions, respiratory depression.

CV: changes in BP, heart failure, tachycardia. GI:

HEPATOTOXICITY, diarrhea, anorexia, cramps, dysphagia,

GI bleeding, nausea, vomiting. GU: crystalluria,

dysuria, frequency, erectile dysfunction, incontinence,

nocturia. Derm: flushing, pruritus, sweating, urticaria.

Hemat: anemia, aplastic anemia, eosinophilia,

leukopenia, thrombocytopenia. Local: irritation at IV

site, phlebitis. MS: myalgia. Misc: ANAPHYLAXIS, chills,

drooling, fever.

Interactions

Drug-Drug: Calcium channel blockers mayqrisk

of cardiovsacular collapse; avoid concomitant use. Additive

CNS depression with CNS depressants, including

alcohol, antihistamines, opioid analgesics,

sedative/hypnotics, and parenteral magnesium sulfate.

qrisk of hepatotoxicity with other hepatotoxic

agents or estrogens.qrisk of arrhythmias with verapamil.

qneuromuscular blocking effects of vecuronium.

Drug-Natural Products: Concomitant use of

kava-kava, valerian, chamomile, or hops canq

CNS depression.

Route/Dosage

PO (Adults): Spasticity—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

qto 100 mg 4 times daily, if needed. Prevention of

malignant hyperthermia—4–8 mg/kg/day in 3–4

divided doses for 1–2 days before procedure, last dose

3–4 hr preop. Posthyperthermic crisis follow-up—

4–8 mg/kg/day in 3–4 divided doses for 1–3 days after

IV treatment.

PO (Children 5 yr): Spasticity—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—4–8 mg/kg/day in 3–4

divided doses for 1–2 days before procedure, last dose

3–4 hr preop. Posthyperthermic crisis follow-up—

4–8 mg/kg/day in 3–4 divided doses for 1–3 days after

IV treatment.

IV (Adults and Children): Treatment of malignant

hyperthermia—at least 1 mg/kg, continued until

symptomspor a cumulative dose of 10 mg/kg has been

given. If symptoms reappear, dose may be repeated.

Prevention of malignant hyperthermia—2.5 mg/kg

given 75 min before surgery.

Availability (generic available)

Capsules: 25 mg, 50 mg, 100 mg. Powder for injection:

20 mg/vial, 250 mg/vial.