Dosing and uses of Norflex (orphenadrine)
Adult dosage forms and strengths
injectable solution
- 30mg/mL
tablet, extended release
- 100mg
Muscle Spasm, Relief of Discomfort Associated with Acute Painful Musculoskeletal Conditions
100 mg PO q12hr Or
60 mg IV/IM q12hr (switch to PO as soon as possible)
Other Indications & Uses
Off-label: Leg cramps resistant to quinine, Parkinson's disease
Pediatric dosage forms and strengths
Safety and efficacy not established
Geriatric dosage forms and strengths
Caution; not recommended for use in elderly because of increased sedation and anticholinergic effects
Muscle spasm, relief of discomfort associated with acute painful musculoskeletal conditions
100 mg PO q12hr Or
60 mg IV/IM q12hr (switch to PO as soon as possible)
Norflex (orphenadrine) adverse (side) effects
Frequency not defined
Dry mouth
Urinary retention
Blurred vision, mydriasis
Drowsiness
Headache
Weakness
Increased IOp
Palpitation
Tachycardia
GI disturbances
CNS stimulation (restlessness, agitation, insomnia, mental confusion)
Lightheadedness
Dizziness
Syncope
Pruritus
Urticarial rash
Tremor
Anaphylactic reactions
Aplastic anemia
Warnings
Contraindications
Hypersensitivity
Narrow-angle glaucoma
Pyloric/duodenal obstruction, BPH, stenosing peptic ulcers, cardiospasm (mega-esophagus), myasthenia gravis, obstructive uropathy, paralytic ileus, ulcerative colitis, toxic megacolon, achalasia
Cautions
Diarrhea, partial obstructive uropathy, open-angle glaucoma, cardiovascular disease, hepatic/renal impairment, cardiac conduction disorder, thyrotoxicosis, history of drug abuse or acute alcoholism
May cause drowsiness/dizziness
May take with food to avoid stomach upset
Injectable form contains sulfites, & precipitates anaphylactic-type reactions in sensitive or asthmatic individuals
Pregnancy and lactation
Pregnancy category: C
Lactation: no data
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Norflex (orphenadrine)
Mechanism of action
May work through central atropine-like effect; anticholinergic activity in brain stem; has euphorigenic and analgesic properties
Pharmacokinetics
Half-life elimination: 14-16 hr
Onset: 2-4 hr (peak)
Duration: 4-6 hr
Metabolism: Liver
Protein binding: 20%
Metabolites: Not fully determined (>8 metabolites)
Excretion: urine (principally)
Administration
IV/IM Administration
Administer IM or IV injection
IV may be given undiluted or diluted in SWI
Give slow IV ~5 min with pt in supine position
Patient should remain in this position for 5-10 min post-injection
To minimize adverse reactions after parenteral administration of the drug, patient should be assisted from recumbent position
Storage
Store at <40°C, preferably between 15-30°C
Protect from freezing
Protect from light; store in tight, light-resistant containers
