Dantrolene Sodium

Mechanism :

Dantrolene is a direct acting skeletal muscle relaxant. It produces relaxation by affecting the contractile response of the muscle at a site beyond the myoneural junction. In skeletal muscle, Dantrolene dissociates excitation-contraction coupling, probably by interfering with the release of Calcium from the sarcoplasmic reticulum by acting on the Ryanodine Receptor Calcium channels.

Indication :

Spasticity
Malignant Hyperthermia

Contraindications :

Contraindicated in acute muscle spasm, hepatic impairment, cardiovascular or respiratory disease. Dantrolene has been associated with symptomatic hepatitis; liver function tests should be performed before starting treatment and at regular intervals.

Dosing :

Malignant Hyperthermia:

1-3 days prior to surgery:

4-8 mg/kg/day orally in four divided doses

75 minutes prior to anesthesia:

2.5 mg/kg intravenously once over an hour and administer additional doses as per requirement.

Spasticity:

<5 years:

0.5 mg/kg orally OD for 1 week, increase dose weekly to 2 mg/kg orally thrice daily; Max: 100 mg orally every 6 hours.

>5 years:

1 mg/kg/day orally in two divided doses. Max: 12 mg/kg/day orally in 4 divided doses.

Adverse Effect :

Drowsiness, dizziness, weakness, malaise, fatigue, diarrhea, anorexia, nausea, headache and rash. Pulmonary edema, thrombophlebitis and muscle weakness with IV use.

Interaction :

Hepatotoxic Drugs, Calcium-Channel Blockers: Avoid concurrent use of dantrolene.
Metoclopramide: Increases the oral bioavailability of dantrolene.
Neuromuscular Blockers: Potentiate vecuronium-induced neuromuscular block.
Verapamil: May cause hyperkalaemia and myocardial depression.
CNS depressive: Additive CNS depressive effect with other CNS depressants.

Hepatic Dose :

Avoid in active hepatic disease, cirrhosis.