Pronunciation: ore-FEN-uh-dreen SIH-trate
Class: Skeletal muscle relaxant
- Injection 30 mg/mL
- Tablets, sustained-release 100 mg
Sandoz Orphenadrine (Canada)
Unknown; may be related to analgesic properties since drug acts on brain stem and does not act directly on muscles; possesses anticholinergic actions.
Readily absorbed from the GI tract. T max is 2 h.
Not fully characterized.
Degraded to 8 known metabolites.
Eliminated through urine (as metabolites, small amount as unchanged) and feces. The t ½ is approximately 14 h (parent drug). The t ½ is 2 to 25 h (metabolites).
4 to 6 h.
Indications and Usage
Adjunctive treatment for acute, painful musculoskeletal conditions.
Treatment of quinine-resistant leg cramps.
Glaucoma; pyloric or duodenal obstruction; stenosing peptic ulcers; prostatic hypertrophy; obstruction of bladder neck; esophageal achalasia; myasthenia gravis.
Dosage and AdministrationAdults
IV/IM 60 mg every 12 h as needed.Adults
PO 100 mg twice daily.
Drug InteractionsAlcohol, other CNS depressants
Increased CNS depression.Haloperidol
Worsening schizophrenic symptoms, decreased haloperidol levels, tardive dyskinesia.Phenothiazines
Decreased effects of phenothiazines.
Laboratory Test Interactions
None well documented.
Tachycardia; palpitations; transient syncope.
Weakness; headache; dizziness; lightheadedness; confusion (especially in elderly); hallucinations; agitation; tremor; drowsiness.
Hypersensitivity reactions (eg, rashes).
Blurred vision; pupil dilation; increased ocular tension.
Dry mouth; vomiting; nausea; constipation; gastric irritation.
Urinary hesitancy and retention.
Category C .
Safety and efficacy not established.
May be more sensitive to anticholinergic effects.
Some products contain bisulfites, which may cause allergic-type reactions in certain persons.
Use drug with caution in patients with cardiac decompensation, coronary insufficiency, cardiac arrhythmias or tachycardia.
Can occur in presence of high environmental temperature.
Cardiac arrhythmias, seizures, coma, shock.
- Tell patient not to increase dosage of medication. Even slight overdose may be highly toxic.
- Instruct patient to take sips of water frequently, suck on ice chips or sugarless hard candy, or chew sugarless gum if dry mouth occurs.
- Advise patient that drug may cause drowsiness or dizziness, and to use caution while driving or performing other tasks requiring mental alertness.
- Instruct patient to report the following symptoms to health care provider: urinary retention, constipation, palpitations, or tremors.
- Instruct patient to avoid alcohol or other CNS depressants.
Copyright © 2009 Wolters Kluwer Health.
More about orphenadrine
- Orphenadrine Citrate (AHFS Monograph)
- Orphenadrine Extended Release Tablets (FDA)
- Orphenadrine Injection (FDA)
- Other brands: Norflex