Overview
Orphenadrine is a centrally-acting skeletal muscle relaxant with anticholinergic properties, used as an adjunct to rest and physical therapy for acute painful musculoskeletal conditions. It works by reducing muscle spasm and associated discomfort through central nervous system effects.
Mechanism of Action
Orphenadrine acts as a centrally-acting skeletal muscle relaxant with anticholinergic properties. It likely produces its effects through central nervous system depression and inhibition of polysynaptic reflexes in the spinal cord and brainstem, reducing muscle spasm and associated pain.
Indications
- Adjunct therapy for acute painful musculoskeletal conditions
- Used with rest, physical therapy, and other measures for discomfort relief
Common Doses
- 100 mg extended-release tablets
Dosage
Adults: Two extended-release tablets daily (one in morning, one in evening)
Contraindications
- Glaucoma
- Pyloric or duodenal obstruction
- Stenosing peptic ulcers
- Prostatic hypertrophy or bladder neck obstruction
- Cardio-spasm (mega-esophagus)
- Myasthenia gravis
- Previous hypersensitivity to orphenadrine
Side Effects
- Dry mouth (most common)
- Tachycardia and palpitations
- Urinary hesitancy or retention
- Blurred vision and pupil dilation
- Increased ocular tension
- Weakness, nausea, vomiting
- Headache, dizziness, drowsiness
- Constipation, gastric irritation
- Hypersensitivity reactions, pruritus
- Hallucinations, agitation, tremor
- Mental confusion (especially in elderly)
- Rare: urticaria, dermatoses, aplastic anemia
Interactions
- Enhanced CNS depression with alcohol, sedatives, and other CNS depressants
- Potentiated anticholinergic effects with other anticholinergic drugs
- Possible additive effects with opioids and benzodiazepines
Counseling Points
- Take one tablet in morning and one in evening as directed
- Avoid alcohol and other CNS depressants
- Do not drive or operate machinery until effects are known
- Report severe dizziness, confusion, or vision changes
- May cause dry mouth - sip water or use sugar-free gum
- Inform provider of all medications being taken