CNS

Muscle Relaxants

CNS Medications

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Examples

cyclobenzaprinebaclofentizanidinedantrolene

Prefix / Suffix: No consistent suffix

Physiology

Muscle spasms result from increased motor neuron activity or direct muscle dysfunction. Relaxants act centrally (CNS) or peripherally (muscle).

Mechanism of Action

Centrally acting agents depress CNS activity to reduce muscle spasm. Dantrolene acts directly on skeletal muscle to inhibit calcium release.

Indications

  • Acute muscle spasm and pain
  • Spasticity (multiple sclerosis, spinal cord injury)
  • Malignant hyperthermia (dantrolene)

Side Effects / Adverse Effects

  • Drowsiness, dizziness
  • Dry mouth (anticholinergic effects)
  • Hepatotoxicity (especially dantrolene, tizanidine)
  • Hypotension
  • Weakness

Contraindications

  • Hepatic impairment
  • Concurrent MAOI use (cyclobenzaprine)
  • Narrow-angle glaucoma

Nursing Considerations

  • Caution patient about drowsiness — avoid driving or operating machinery
  • Avoid alcohol and other CNS depressants
  • Monitor liver function (especially dantrolene and tizanidine)
  • Use for short-term (2–3 weeks) for acute spasm
  • Taper baclofen — abrupt withdrawal can cause hallucinations, seizures
  • Implement fall precautions

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Disclaimer: PharmPal Nurse is for education only and is not medical advice. Do not use it to diagnose, treat, prescribe, or make patient-care decisions; always verify with current drug references, your instructor, facility policy, and a licensed provider. In emergencies, call local emergency services.