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Orphenadrine

Pronunciation

Pronunciation

(or FEN a dreen)

Index Terms

  • Orphenadrine Citrate

Dosage Forms

Excipient information presented when available (limited, particularly for generics); consult specific product labeling. [DSC] = Discontinued product

Solution, Injection, as citrate:

Norflex: 30 mg/mL (2 mL [DSC]) [contains sodium metabisulfite]

Generic: 30 mg/mL (2 mL)

Solution, Injection, as citrate [preservative free]:

Generic: 30 mg/mL (2 mL)

Tablet Extended Release 12 Hour, Oral, as citrate:

Generic: 100 mg

Brand Names: U.S.

  • Norflex [DSC]

Pharmacologic Category

  • Skeletal Muscle Relaxant

Pharmacology

Indirect skeletal muscle relaxant thought to work by central atropine-like effects; has some euphorigenic and analgesic properties

Metabolism

Extensively hepatic

Excretion

Primarily urine (8% as unchanged drug)

Onset of Action

Peak effect: Oral: Within 2 to 4 hours

Duration of Action

4 to 6 hours

Half-Life Elimination

14 to 16 hours

Protein Binding

20%

Use: Labeled Indications

Treatment of muscle spasm associated with acute painful musculoskeletal conditions

Contraindications

Hypersensitivity to orphenadrine or any component of the formulation; glaucoma; GI obstruction, stenosing peptic ulcer; prostatic hypertrophy, bladder neck obstruction; cardiospasm; myasthenia gravis

Dosing: Adult

Muscle spasms:

Oral: 100 mg twice daily

IM, IV: 60 mg every 12 hours

Dosing: Geriatric

Refer to adult dosing.

Dosing: Renal Impairment

No dosage adjustment provided in manufacturer’s labeling.

Dosing: Hepatic Impairment

No dosage adjustment provided in manufacturer’s labeling.

Administration

Do not crush sustained release drug product.

Storage

Store at controlled room temperature. Protect injection solution from light.

Drug Interactions

AbobotulinumtoxinA: Anticholinergic Agents may enhance the anticholinergic effect of AbobotulinumtoxinA. Monitor therapy

Acetylcholinesterase Inhibitors: Anticholinergic Agents may diminish the therapeutic effect of Acetylcholinesterase Inhibitors. Acetylcholinesterase Inhibitors may diminish the therapeutic effect of Anticholinergic Agents. Monitor therapy

Aclidinium: May enhance the anticholinergic effect of Anticholinergic Agents. Avoid combination

Alcohol (Ethyl): May enhance the CNS depressant effect of Orphenadrine. Avoid combination

Anticholinergic Agents: May enhance the adverse/toxic effect of other Anticholinergic Agents. Monitor therapy

Azelastine (Nasal): CNS Depressants may enhance the CNS depressant effect of Azelastine (Nasal). Avoid combination

Brimonidine (Topical): May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Cannabis: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Chlorphenesin Carbamate: May enhance the adverse/toxic effect of CNS Depressants. Monitor therapy

Cimetropium: Anticholinergic Agents may enhance the anticholinergic effect of Cimetropium. Avoid combination

CNS Depressants: May enhance the CNS depressant effect of Orphenadrine. Avoid combination

Dimethindene (Systemic): May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Dronabinol: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Eluxadoline: Anticholinergic Agents may enhance the constipating effect of Eluxadoline. Avoid combination

Gastrointestinal Agents (Prokinetic): Anticholinergic Agents may diminish the therapeutic effect of Gastrointestinal Agents (Prokinetic). Monitor therapy

Glucagon: Anticholinergic Agents may enhance the adverse/toxic effect of Glucagon. Specifically, the risk of gastrointestinal adverse effects may be increased. Avoid combination

Glycopyrrolate (Oral Inhalation): Anticholinergic Agents may enhance the anticholinergic effect of Glycopyrrolate (Oral Inhalation). Avoid combination

Ipratropium (Oral Inhalation): May enhance the anticholinergic effect of Anticholinergic Agents. Avoid combination

Itopride: Anticholinergic Agents may diminish the therapeutic effect of Itopride. Monitor therapy

Kava Kava: May enhance the adverse/toxic effect of CNS Depressants. Monitor therapy

Levosulpiride: Anticholinergic Agents may diminish the therapeutic effect of Levosulpiride. Avoid combination

Lofexidine: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Magnesium Sulfate: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

MetyroSINE: CNS Depressants may enhance the sedative effect of MetyroSINE. Monitor therapy

Minocycline: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Mirabegron: Anticholinergic Agents may enhance the adverse/toxic effect of Mirabegron. Monitor therapy

Nabilone: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Nitroglycerin: Anticholinergic Agents may decrease the absorption of Nitroglycerin. Specifically, anticholinergic agents may decrease the dissolution of sublingual nitroglycerin tablets, possibly impairing or slowing nitroglycerin absorption. Avoid combination

OnabotulinumtoxinA: Anticholinergic Agents may enhance the anticholinergic effect of OnabotulinumtoxinA. Monitor therapy

Oxatomide: May enhance the anticholinergic effect of Anticholinergic Agents. Avoid combination

Paraldehyde: CNS Depressants may enhance the CNS depressant effect of Paraldehyde. Avoid combination

Piribedil [INT]: CNS Depressants may enhance the CNS depressant effect of Piribedil [INT]. Monitor therapy

Potassium Chloride: Anticholinergic Agents may enhance the ulcerogenic effect of Potassium Chloride. Management: Patients on drugs with substantial anticholinergic effects should avoid using any solid oral dosage form of potassium chloride. Avoid combination

Pramipexole: CNS Depressants may enhance the sedative effect of Pramipexole. Monitor therapy

Pramlintide: May enhance the anticholinergic effect of Anticholinergic Agents. These effects are specific to the GI tract. Consider therapy modification

Ramosetron: Anticholinergic Agents may enhance the constipating effect of Ramosetron. Monitor therapy

RimabotulinumtoxinB: Anticholinergic Agents may enhance the anticholinergic effect of RimabotulinumtoxinB. Monitor therapy

ROPINIRole: CNS Depressants may enhance the sedative effect of ROPINIRole. Monitor therapy

Rotigotine: CNS Depressants may enhance the sedative effect of Rotigotine. Monitor therapy

Rufinamide: May enhance the adverse/toxic effect of CNS Depressants. Specifically, sleepiness and dizziness may be enhanced. Monitor therapy

Secretin: Anticholinergic Agents may diminish the therapeutic effect of Secretin. Management: Avoid using drugs with substantial anticholinergic effects in patients receiving secretin whenever possible. If such agents must be used in combination, monitor closely for a diminished response to secretin. Consider therapy modification

Selective Serotonin Reuptake Inhibitors: CNS Depressants may enhance the adverse/toxic effect of Selective Serotonin Reuptake Inhibitors. Specifically, the risk of psychomotor impairment may be enhanced. Monitor therapy

Tetrahydrocannabinol: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Thalidomide: CNS Depressants may enhance the CNS depressant effect of Thalidomide. Avoid combination

Thiazide and Thiazide-Like Diuretics: Anticholinergic Agents may increase the serum concentration of Thiazide and Thiazide-Like Diuretics. Monitor therapy

Tiotropium: Anticholinergic Agents may enhance the anticholinergic effect of Tiotropium. Avoid combination

Umeclidinium: May enhance the anticholinergic effect of Anticholinergic Agents. Avoid combination

Adverse Reactions

Frequency not defined.

Cardiovascular: Palpitation, tachycardia

Central nervous system: Agitation, dizziness, drowsiness, euphoria, hallucination, headache, mental confusion

Dermatologic: Pruritus, urticaria

Gastrointestinal: Constipation, gastric irritation, nausea, vomiting, xerostomia

Genitourinary: Urination hesitancy, urinary retention

Hematologic: Aplastic anemia (rare)

Neuromuscular & skeletal: Tremor, weakness

Ocular: Blurred vision, intraocular pressure increased, nystagmus, pupil dilation

Respiratory: Nasal congestion

Miscellaneous: Anaphylactic reaction (injection, rare), hypersensitivity

Warnings/Precautions

Concerns related to adverse effects:

• CNS depression: May cause CNS depression, which may impair physical or mental abilities; patients must be cautioned about performing tasks which require mental alertness (eg, operating machinery or driving).

Disease-related concerns:

• Cardiovascular disease: Use with caution in patients with HF, cardiac decompensation, coronary insufficiency, tachycardia, or cardiac arrhythmias.

• Drug abuse: Use with caution in patients with a history of drug abuse or acute alcoholism; potential for abuse exists.

Concurrent drug therapy issues:

• Sedatives: Effects may be potentiated when used with other sedative drugs or ethanol.

Dosage form specific issues:

• Sulfites: Injection contains sodium bisulfite which may cause allergic reaction in some individuals.

Other warnings/precautions:

• Long-term use: Has not been evaluated for continuous long-term use; monitor closely.

Pregnancy Risk Factor

C

Pregnancy Considerations

Animal reproduction studies have not been conducted.

Patient Education

• Discuss specific use of drug and side effects with patient as it relates to treatment. (HCAHPS: During this hospital stay, were you given any medicine that you had not taken before? Before giving you any new medicine, how often did hospital staff tell you what the medicine was for? How often did hospital staff describe possible side effects in a way you could understand?)

• Patient may experience nausea, vomiting, dry mouth, headache, constipation, or fatigue. Have patient report immediately to prescriber severe loss of strength and energy, severe dizziness, passing out, confusion, anxiety, tachycardia, arrhythmia, vision changes, urinary retention, hallucinations, or tremors (HCAHPS).

• Educate patient about signs of a significant reaction (eg, wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat). Note: This is not a comprehensive list of all side effects. Patient should consult prescriber for additional questions.

Intended Use and Disclaimer: Should not be printed and given to patients. This information is intended to serve as a concise initial reference for healthcare professionals to use when discussing medications with a patient. You must ultimately rely on your own discretion, experience, and judgment in diagnosing, treating, and advising patients.

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