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Dantrolene Sodium

Pronunciation

Pronunciation: dan-troe-LEEN SO-dee-uhm
Class: Skeletal muscle relaxant

Trade Names

Dantrium
- Capsules 25 mg
- Capsules 50 mg
- Capsules 100 mg

Dantrium Intravenous
- Powder for Injection 20 mg/vial

Revonto
- Lyophilized Powder for Injection 20 mg/vial

Pharmacology

Affects contraction of muscle at site beyond myoneural junction and directly on muscle itself; believed to interfere with calcium release from sarcoplasmic reticulum. Affects CNS, causing drowsiness, dizziness, and generalized weakness.

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Pharmacokinetics

Absorption

Oral

Absorption is incomplete and slow, but consistent.

Distribution

Significantly protein bound, mostly albumin.

Metabolism

Metabolized in the liver to the major metabolites 5-hydroxy dantrole and an acetylamino metabolite.

Elimination

Half-life is 4 to 8 h (IV) and 9 h (oral).

Indications and Usage

Control of spasticity associated with spinal cord injury, stroke, cerebral palsy or multiple sclerosis; prophylaxis, treatment and postcrisis therapy of malignant hyperthermia.

Unlabeled Uses

Management of exercise-induced muscle pain, neuroleptic malignant syndrome, heat stroke.

Contraindications

Active hepatic disease; muscle spasm resulting from rheumatic disorders; where spasticity is used to sustain upright posture and balance in locomotion or to obtain or maintain increased function.

Dosage and Administration

Chronic Spasticity
Adults

PO Initial dose 25 mg every day; increase at 4 to 7 day intervals to 25 mg twice daily to 4 times daily, up to max 100 mg twice daily to 4 times daily, if necessary.

Children

PO Initial dose 0.5 mg/kg twice daily; increase to 0.5 mg/kg 3 times daily to 4 times daily, then by increments of 0.5 mg/kg, up to 3 mg/kg twice daily to 4 times daily, if necessary. Max 100 mg 4 times daily.

Malignant Hyperthermia
Adults and Children Preoperative prophylaxis

PO 4 to 8 mg/kg/day in 3 or 4 divided doses for 1 or 2 days prior to surgery with last dose given 3 to 4 h before surgery or IV 2.5 mg/kg approximately 75 min before anesthesia. Infused over 1 h. May repeat during surgery, if needed.

Treatment

IV 1 mg/kg by continuous rapid push; evaluate and repeat as needed or until cumulative total dose is up to 10 mg/kg. May be repeated if psysiologic and metabolic abnormalities reappear.

Postcrisis follow-up

PO 4 to 8 mg/kg/day in 4 divided doses for 1 to 3 days to prevent recurrence. If IV route must be utilized, start with at least 1 mg/kg, as needed.

General Advice

  • Ensure good IV site using large peripheral vein; medication is very irritating to tissues.
  • Reconstitute powder for IV infusion in 60 mL of sterile water without bacteriostatic agent.
  • Shake vial for approximately 20 sec or until solution is clear.
  • Do not transfer reconsitituted dantrolene to large glass bottles for prophylactic infusion.
  • Dextrose 5% injection, sodium chloride 0.9% injection, and other acidic solutions are not compatible.

Storage/Stability

Store vials and reconstituted dantrolene between 68° and 77°F. Protect from direct light. Use reconstituted solutions within 6 h of reconstitution.

Drug Interactions

Clofibrate

Plasma protein binding of dantrolene reduced.

Estrogens

Women receiving these may be at increased risk for hepatotoxicity.

Verapamil

Hyperkalemia and myocardial depression possible.

Warfarin

Plasma protein binding of dantrolene reduced.

Adverse Reactions

Caused by oral administration except where otherwise indicated.

Cardiovascular

Erratic BP, phlebitis, tachycardia.

CNS

Dizziness; drowsiness; fatigue; general malaise; headache; increased nervousness; insomnia, mental depression or confusion; lightheadedness; seizures; speech disturbances; weakness.

Dermatologic

Abnormal hair growth, acne-like rash, eczematoid eruption, erythema (IV), pruritus, sweating, urticaria (IV).

EENT

Visual disturbance, diplopia, alteration of taste.

GI

Abdominal cramps, anorexia, constipation, bleeding, diarrhea, dysphagia, gastric irritation.

Genitourinary

Crystalluria, difficult erection, dysuria, hematuria, increased urinary frequency, nocturia, urinary incontinence, urinary retention.

Hepatic

Hepatitis.

Respiratory

Pleural effusion with pericarditis, pulmonary edema (IV).

Miscellaneous

Backache, chills, excessive tearing, fever, feeling of suffocation, myalgia, thrombophlebitis (IV).

Precautions

Warnings

Should not be used in conditions other than those recommended.

Hepatotoxicity

The incidence of symptomatic (fatal and nonfatal) hepatitis is lower with doses up to 400 mg/day compared with 800 mg/day or greater. Overt hepatitis was most frequent during the third and twelfth mo, but may occur at anytime. Risk is higher in females, patients older than 35 y, and with concurrent therapy. Use only in conjunction with liver monitoring.


Pregnancy

Category C (parenteral).

Lactation

Excreted in breast milk. Do not use in breast-feeding women.

Children

Safety in children younger than 5 y of age not established.

Hepatic Function

Fatal and nonfatal liver disorders may occur; use drug with caution in patients with preexisting hepatic impairment and in women and patients older than 35 y of age.

Special Risk Patients

Use drug with caution in patients with impaired pulmonary function (especially COPD) or cardiac function.

Photosensitivity

Photosensitization may occur.

Extravasation

Because of the high pH of the IV formulation, prevent extravasation into the surrounding tissue.

IV Dantrolene

IV dantrolene is also associated with the loss of grip strength and weakness in the legs.

Long-term use

Safety and efficacy not established; use only if significant pain or disability is present or nursing care is reduced. Consider carcinogenicity risk and liver damage with long-term use. Discontinue therapy if no benefit within 45 days.

Malignant hyperthermia

Supportive care should be foremost in treatment (ie, concurrent with dantrolene therapy).

Patient Information

  • Teach patient and family the name, action, administration, and side effects of dantrolene.
  • Emphasize importance of follow-up exams and laboratory work to monitor drug therapy.
  • Instruct patients to report these symptoms to their health care provider: weakness, malaise, fatigue, nausea, diarrhea, skin rash, itching, bloody or black tarry stools, yellowish discoloration of skin.
  • Instruct patient to avoid intake of alcoholic beverages or other CNS depressants.
  • Advise patient that drug may cause drowsiness and to use caution while driving or performing other tasks requiring mental alertness.
  • Caution patient to avoid exposure to sunlight and to use sunscreen or wear protective clothing to avoid photosensitivity reaction.
  • Caution patient that dantrolene may decrease grip strength and increase weakness of leg muscles, especially when walking down stairs.
  • Advise patients to exercise caution in eating on day of administration because difficulty swallowing and choking is possible.

Copyright © 2009 Wolters Kluwer Health.

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