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orphenadrine (or-fen-a-dreen)

Antiflex, Banflex, Disipal, Flexoject, Flexon, Mio-Rel, Myolin, Myotrol, Norflex, Orfro, Orphenate


Therapeutic: skeletal muscle relaxants (centrally acting)

Pharmacologic: diphenhydramine analogues


Adjunct to rest and physical therapy in the treatment of muscle spasm associated with acute painful musculoskeletal conditions. Adjunct therapy of Parkinson's disease (Canadian labeling only).


Skeletal muscle relaxation, probably due to CNS depression. Therapeutic Effects: Skeletal muscle relaxation, with decreased discomfort.

Adverse Reactions/Side Effects

CNS: CNS excitation, confusion, dizziness, drowsiness. EENT: blurred vision, dry eyes. CV: orthostatic hypotension, tachycardia. GI: constipation, dry mouth. GU: urinary retention.


Examination and Evaluation

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

  • Assess blood pressure (BP) when patient assumes a more upright position (lying to standing, sitting to standing, lying to sitting). Document orthostatic hypotension and contact physician when systolic BP falls >20 mm Hg, or diastolic BP falls >10 mm Hg.

  • Assess heart rate, ECG, and heart sounds, especially during exercise (See Appendices G, H). Report rapid heart rate (tachycardia) or symptoms of other 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, irritability nervousness, or other signs of CNS excitation (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).

  • 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 to report vision disturbances, including blurred vision or excessively dry eyes.



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