Can orphenadrine cause blurry vision?

Orphenadrine and Blurry Vision

Yes, orphenadrine can cause blurry vision as an adverse effect due to its anticholinergic properties. 1

Mechanism and Occurrence

• Orphenadrine is a centrally acting skeletal muscle relaxant with a structure similar to diphenhydramine, exhibiting anticholinergic effects 2
• Blurred vision is specifically listed as a common adverse effect in the FDA drug label for orphenadrine 1
• The anticholinergic properties of orphenadrine can cause pupillary dilation and interference with accommodation, leading to visual disturbances 2, 3

Risk Factors and Considerations

• Blurred vision is more likely to occur with higher dosages of orphenadrine 1
• Patients with pre-existing eye conditions may be at increased risk:
  • Those with narrow angles are particularly susceptible to angle-closure glaucoma when taking anticholinergic medications 3
  • Patients with glaucoma should avoid orphenadrine as it is contraindicated in this population 2
• Elderly patients may be more sensitive to the anticholinergic effects of orphenadrine 2, 1

Associated Anticholinergic Effects

Blurred vision typically occurs alongside other anticholinergic symptoms, including:

• Dry mouth (usually the first adverse effect to appear) 1
• Pupillary dilation 3
• Increased ocular tension 1
• Urinary hesitancy or retention 1
• Constipation 1
• Tachycardia and palpitations 1

Management of Orphenadrine-Induced Blurry Vision

• Dose reduction is typically the first approach and can usually eliminate this adverse effect 1
• In cases where blurry vision persists or is severe, discontinuation of the medication may be necessary 2
• Consider alternative muscle relaxants with fewer anticholinergic properties if treatment is still required 2
• Monitor for signs of increased intraocular pressure, especially in patients with risk factors for angle-closure glaucoma 3

Special Populations

• Elderly patients: Use with caution as they may experience more pronounced anticholinergic effects, including mental confusion 2, 1
• Patients with cardiovascular conditions: Orphenadrine should be used cautiously in patients with tachycardia, cardiac decompensation, coronary insufficiency, and cardiac arrhythmias 2
• Patients with prostatic hypertrophy or bladder outlet obstruction: Orphenadrine is contraindicated due to its anticholinergic effects 2

Clinical Pearls

• When prescribing orphenadrine, warn patients about the possibility of blurred vision, especially when driving or operating machinery 1
• Consider the risk-benefit ratio before prescribing orphenadrine to patients with pre-existing visual disturbances or at risk for angle-closure glaucoma 3
• The visual effects are typically reversible upon dose reduction or discontinuation 1