Recommended Dosage of Orphenadrine for Adults
The recommended dose of orphenadrine for adults is 100 mg orally twice daily. 1
Dosage Forms and Administration Routes
- Orphenadrine is available in both parenteral and oral formulations:
Clinical Considerations
Efficacy and Safety
- Orphenadrine has anticholinergic properties and is used primarily for muscle relaxation 2
- The therapeutic window is relatively narrow, with toxic effects possible at higher doses 3
- Doses up to 100 mg twice daily are generally well-tolerated in adult patients 1, 3
Toxicity Concerns
- Ingestion of 2-3 g (20-30 tablets of 100 mg) has been associated with fatality in adults 2
- Toxic effects include anticholinergic symptoms (confusion, drowsiness, tachycardia), seizures, and potential cardiotoxicity 3, 4
- Immediate release formulations may produce higher peak concentrations and potentially more severe toxicity compared to sustained-release formulations at equivalent doses 3
Special Populations
Elderly Patients
- Consider starting at the lower end of the dosing range due to potential increased sensitivity to anticholinergic effects 3
- Monitor closely for side effects such as confusion, urinary retention, and tachycardia 3
Patients with Renal or Hepatic Impairment
- Dose adjustment may be necessary as orphenadrine is primarily metabolized by the liver and excreted by the kidneys 4
- The elimination half-life of approximately 10.2 hours may be prolonged in patients with impaired hepatic or renal function 4
Combination Therapy
- When used in fixed combination with diclofenac (as in some countries), the standard dose is 30 mg orphenadrine with 75 mg diclofenac 5
- This combination has shown efficacy in postoperative pain management 5