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Orphenadrine

Medically reviewed by Drugs.com. Last updated on May 31, 2020.

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:

Generic: 30 mg/mL (2 mL)

Solution, Injection, as citrate [preservative free]:

Generic: 30 mg/mL (2 mL [DSC])

Tablet Extended Release 12 Hour, Oral, as citrate:

Generic: 100 mg

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

Avoid use (Beers Criteria [AGS 2019]).

Administration

Oral: Do not crush sustained-release drug product.

Bariatric surgery: Tablet, extended release: Some institutions may have specific protocols that conflict with these recommendations; refer to institutional protocols as appropriate. ER tablet should be swallowed whole. Do not cut, chew, or crush. No alternative oral formulations are available (injectable only). If safety and efficacy can be effectively monitored, no change in formulation or administration is required after bariatric surgery; however, consider IV or IM administration for acute relief.

Storage

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

Drug Interactions

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

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

Amantadine: May enhance the anticholinergic effect of Anticholinergic Agents. Monitor therapy

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

Botulinum Toxin-Containing Products: May enhance the anticholinergic effect of Anticholinergic Agents. Monitor therapy

Botulinum Toxin-Containing Products: Muscle Relaxants (Centrally Acting) may enhance the adverse/toxic effect of Botulinum Toxin-Containing Products. Specifically, the risk for increased muscle weakness may be enhanced. Monitor therapy

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

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

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

Cannabidiol: 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 (Topical): 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. Monitor therapy

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

Glycopyrronium (Topical): May enhance the anticholinergic effect of Anticholinergic Agents. 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

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

Lofexidine: May enhance the CNS depressant effect of CNS Depressants. Management: Drugs listed as exceptions to this monograph are discussed in further detail in separate drug interaction monographs. Monitor therapy

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

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

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

Minocycline (Systemic): 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. Monitor therapy

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

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

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

Piribedil: CNS Depressants may enhance the CNS depressant effect of Piribedil. 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

Potassium Citrate: Anticholinergic Agents may enhance the ulcerogenic effect of Potassium Citrate. 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. Avoid combination

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

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

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 concomitant use of anticholinergic agents and secretin. Discontinue anticholinergic agents at least 5 half-lives prior to administration of secretin. Consider therapy modification

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

Tetrahydrocannabinol and Cannabidiol: 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

Tolperisone: May enhance the adverse/toxic effect of Muscle Relaxants (Centrally Acting). Management: Monitor for increased sedation or CNS effects if tolperisone is combined with other centrally acting muscle relaxants. Consider decreasing the tolperisone dose if these agents are combined. Consider therapy modification

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

Adverse Reactions

Frequency not defined.

Cardiovascular: Palpitations, tachycardia

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

Dermatologic: Pruritus, urticaria

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

Genitourinary: Urinary retention, urination hesitancy

Hypersensitivity: Hypersensitivity reaction

Neuromuscular & skeletal: Tremor, weakness

Ophthalmic: Blurred vision, increased intraocular pressure, mydriasis, nystagmus

Respiratory: Nasal congestion

<1%, postmarketing, and/or case reports: Anaphylaxis (injection), aplastic anemia

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 heart failure, cardiac decompensation, coronary insufficiency, tachycardia, or cardiac arrhythmias.

• Drug abuse: Use with caution in patients with a history of drug abuse or acute alcoholism; euphoria may occur at therapeutic doses and the 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

What is this drug used for?

• It is used to relax muscles.

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

• Nausea

• Vomiting

• Dry mouth

• Headache

• Constipation

• Fatigue

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

• Severe loss of strength and energy

• Severe dizziness

• Passing out

• Confusion

• Anxiety

• Fast heartbeat

• Abnormal heartbeat

• Agitation

• Vision changes

• Unable to pass urine

• Sensing things that seem real but are not

• Tremors

• Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.

Note: This is not a comprehensive list of all side effects. Talk to your doctor if you have questions.

Consumer Information Use and Disclaimer: This information should not be used to decide whether or not to take this medicine or any other medicine. Only the healthcare provider has the knowledge and training to decide which medicines are right for a specific patient. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a limited summary of general information about the medicine's uses from the patient education leaflet and is not intended to be comprehensive. This limited summary does NOT include all information available about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this medicine. This information is not intended to provide medical advice, diagnosis or treatment and does not replace information you receive from the healthcare provider. For a more detailed summary of information about the risks and benefits of using this medicine, please speak with your healthcare provider and review the entire patient education leaflet.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.