Indications

Relaxo (Dantrolene) is indicated for two main purposes:

• Chronic Spasticity: Used to control clinical spasticity resulting from conditions like spinal cord injury, stroke, cerebral palsy, or multiple sclerosis. It is most beneficial for patients whose rehabilitation is hindered by spasticity, particularly when the condition is reversible. The decision to continue long-term therapy is justified if it leads to a significant reduction in painful spasticity, reduces required nursing care, or relieves annoying symptoms for the patient.
• Malignant Hyperthermia (MH):
  • Preoperatively: To prevent or lessen signs of MH in susceptible patients before anesthesia or surgery.
  • Post-crisis: To prevent the recurrence of MH signs after a crisis.

Pharmacology

Dantrolene works directly on skeletal muscle, beyond the neuromuscular junction. It dissociates the excitation-contraction coupling by interfering with the release of calcium ions (Ca++) from the sarcoplasmic reticulum, which leads to muscle relaxation.

Dosage & Administration

• Chronic Spasticity:
  • Adults: The initial dose is 25 mg twice per day, gradually increasing by 25-50 mg per day at weekly intervals. The maximum daily dose is 400 mg. Each dosage level should be maintained for seven days to assess response.
  • Pediatric Patients: The initial dose is 0.5 mg/kg once daily for seven days, followed by a gradual increase to 2 mg/kg three times a day.
• Malignant Hyperthermia:
  • Preoperatively: 4 to 8 mg/kg/day orally in 3 or 4 divided doses for one to two days before surgery. The final dose is given 3-4 hours before the procedure with a minimal amount of water.
  • Post-Crisis: 4 to 8 mg/kg/day orally in four divided doses for one to three days to prevent recurrence.

Interaction

• CNS Depressants: Concomitant use with sedatives and tranquilizers may lead to increased drowsiness.
• Estrogen: The risk of hepatotoxicity is higher in women over 35 years of age who are also receiving estrogen therapy.

Contraindications

Relaxo is contraindicated in patients with active hepatic diseases such as hepatitis and cirrhosis.

Side Effects

The most common side effects are drowsiness, dizziness, weakness, fatigue, and diarrhea. These are usually transient and can be managed by starting with a low dose and gradually increasing it. If diarrhea is severe or recurs upon re-administration, the drug should be withdrawn permanently.

Pregnancy & Lactation

• Pregnancy: Relaxo is a Pregnancy Category C drug. It should only be used if the potential benefit justifies the potential risk to the fetus.
• Lactation: It should not be used in nursing mothers.

Precautions & Warnings

• Liver Damage: Fatal and non-fatal liver disorders can occur. Liver function studies (SGOT, SGPT, etc.) should be performed before and at appropriate intervals during therapy. If symptoms of hepatitis or jaundice appear, the drug must be discontinued immediately.
• Driving & Occupations: Patients should be advised against driving or operating hazardous machinery due to potential drowsiness.
• Photosensitivity: The drug may cause a photosensitivity reaction, so caution is advised regarding sun exposure.
• Special Caution: Use with caution in females, patients over 35, and those with impaired pulmonary or severe cardiac function, or a history of liver disease.

Use in Special Populations

• Pediatric Patients: The long-term safety in children under 5 years has not been established. A careful benefit-risk assessment is necessary for long-term use in this population.

Therapeutic Class

Relaxo is a centrally acting skeletal muscle relaxant.

Storage Conditions

Store in a cool, dry place, protected from light.