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cyclobenzaprine (sye-kloe-ben-za-preen)

Amrix, Flexeril


Therapeutic: skeletal muscle relaxants (centrally acting)


Management of acute painful musculoskeletal conditions associated with muscle spasm. Unlabeled Use: Management of fibromyalgia.


Reduces tonic somatic muscle activity at the level of the brainstem. Structurally similar to tricyclic antidepressants. Therapeutic Effects: Reduction in muscle spasm and hyperactivity without loss of function.

Adverse Reactions/Side Effects

CNS: dizziness, drowsiness, confusion, fatigue, headache, nervousness. EENT: dry mouth, blurred vision. CV: arrhythmias. GI: constipation, dyspepsia, nausea, unpleasant taste. GU: urinary retention.


Examination and Evaluation

  • Assess patient's pain, stiffness, and ROM to help document antispasm effects.

  • If treating fibromyalgia, use visual analogue scales and other appropriate pain scales to assess the patient's pain and help document effects of drug therapy.

  • Assess heart rate, ECG, and heart sounds, especially during exercise (See Appendices G, H). Report any rhythm disturbances or symptoms of increased arrhythmias, including palpitations, chest discomfort, shortness of breath, fainting, and fatigue/weakness.

  • Assess dizziness that might affect gait, balance, and other functional activities (See Appendix C). Report balance problems and functional limitations to the physician, and caution the patient and family/caregivers to guard against falls and trauma.

  • Be alert for confusion, nervousness, or other alterations in mental status (See Appendix D). Notify physician promptly if these symptoms become problematic.


  • Implement appropriate manual therapy techniques, physical agents, and therapeutic exercises to reduce pain and wean patient off muscle relaxants as soon as possible.

  • Help patient explore other nonpharmacologic methods to reduce chronic pain, such as relaxation techniques, exercise, counseling, and so forth.

  • Implement fall prevention strategies, especially if balance is impaired (See Appendix E).

  • Because of the risk of cardiac arrhythmias, use caution during aerobic exercise and other forms of therapeutic exercise. Terminate exercise if patient exhibits untoward symptoms (chest pain, shortness of breath, unusual fatigue) or displays other criteria for exercise termination (See Appendix L).

  • To minimize orthostatic hypotension, patient should move slowly when assuming a more upright position.

Patient/Client-Related Instruction

  • Inform patient that long-term use can cause tolerance and dependence; encourage adherence to physical therapy so that drug therapy can be discontinued as soon as possible.

  • Inform patient that this drug may cause severe drowsiness, dizziness, and reduced psychomotor skills. Patients should avoid driving or other activities that require concentration and fast reactions.

  • Advise patient to avoid alcohol and other CNS depressants because of the increased risk of sedation and adverse effects.

  • Warn patient about anticholinergic effects such as dry mouth, constipation, urinary retention, sedation, and weakness; anticholinergic effects are often more severe in older adults.

  • Instruct patient and family/caregivers ...

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