Pain, musculoskeletal, acute:
Note: For skeletal muscle spasm and/or pain (eg, low back pain, neck pain) with muscle spasm, usually in combination with a nonsteroidal anti-inflammatory drug and/or acetaminophen (Ref). In general, muscle relaxants should be used temporarily (eg, for a few days or intermittently for a few days when needed) (Ref).
Oral: 100 mg twice daily.
IM, IV: 60 mg; may repeat every 12 hours.
Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.
There are no dosage adjustments provided in the manufacturer's labeling.
There are no dosage adjustments provided in the manufacturer's labeling.
Avoid use (Ref).
The following adverse drug reactions and incidences are derived from product labeling unless otherwise specified.
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
Hypersensitivity to orphenadrine or any component of the formulation; glaucoma; pyloric or duodenal obstruction, stenosing peptic ulcer; prostatic hypertrophy, bladder neck obstruction; cardiospasm (megaesophagus); myasthenia gravis
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:
• Abuse potential: Use with caution in patients with a history of substance use disorder; euphoria may occur at therapeutic doses and the potential for abuse exists.
• Cardiovascular disease: Use with caution in patients with heart failure, cardiac decompensation, coronary insufficiency, tachycardia, or cardiac arrhythmias.
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.
Excipient information presented when available (limited, particularly for generics); consult specific product labeling.
Solution, Injection, as citrate:
Generic: 30 mg/mL (2 mL)
Tablet Extended Release 12 Hour, Oral, as citrate:
Generic: 100 mg
Yes
Solution (Orphenadrine Citrate Injection)
30 mg/mL (per mL): $9.36
Tablet, 12-hour (Orphenadrine Citrate ER Oral)
100 mg (per each): $2.18 - $2.31
Disclaimer: A representative AWP (Average Wholesale Price) price or price range is provided as reference price only. A range is provided when more than one manufacturer's AWP price is available and uses the low and high price reported by the manufacturers to determine the range. The pricing data should be used for benchmarking purposes only, and as such should not be used alone to set or adjudicate any prices for reimbursement or purchasing functions or considered to be an exact price for a single product and/or manufacturer. Medi-Span expressly disclaims all warranties of any kind or nature, whether express or implied, and assumes no liability with respect to accuracy of price or price range data published in its solutions. In no event shall Medi-Span be liable for special, indirect, incidental, or consequential damages arising from use of price or price range data. Pricing data is updated monthly.
IM: Administer deep IM.
IV: Administer undiluted via slow IV push over 2 to 5 minutes (Ref). Also refer to institution-specific policies and procedures.
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.
Pain, musculoskeletal, acute: Adjunct to rest, physical therapy, and other measures for the treatment of discomfort associated with acute painful musculoskeletal conditions.
Norflex may be confused with norfloxacin, Noroxin
Beers Criteria: Orphenadrine is identified in the Beers Criteria as a potentially inappropriate medication to be avoided in patients 65 years and older (independent of diagnosis or condition) because most muscle relaxants are poorly tolerated in older adults due to anticholinergic effects caused by some muscle relaxants, risk of sedation, and an increased risk of fracture. Orphenadrine has strong anticholinergic properties. In addition, efficacy is questionable at doses tolerated by geriatric patients (Beers Criteria [AGS 2023]).
Biorphen: Brand name for orphenadrine [Great Britain] but is also the brand name for phenylephrine (systemic) [US]
Flexin: Brand name for orphenadrine [Israel] but is also the brand name for cyclobenzaprine [Chile] and diclofenac [Argentina]
Flexin [Israel] may be confused with Floxin which is a brand name for flunarizine [Thailand], norfloxacin [South Africa], ofloxacin [US, Canada], and perfloxacin [Philippines]
Substrate of CYP1A2 (minor), CYP2B6 (minor), CYP2D6 (minor), CYP3A4 (minor); Note: Assignment of Major/Minor substrate status based on clinically relevant drug interaction potential
Note: Interacting drugs may not be individually listed below if they are part of a group interaction (eg, individual drugs within “CYP3A4 Inducers [Strong]” are NOT listed). For a complete list of drug interactions by individual drug name and detailed management recommendations, use the drug interactions program by clicking on the “Launch drug interactions program” link above.
Acetylcholinesterase Inhibitors: May diminish the therapeutic effect of Agents with Clinically Relevant Anticholinergic Effects. Agents with Clinically Relevant Anticholinergic Effects may diminish the therapeutic effect of Acetylcholinesterase Inhibitors. Risk C: Monitor therapy
Aclidinium: May enhance the anticholinergic effect of Agents with Clinically Relevant Anticholinergic Effects. Risk X: Avoid combination
Agents with Clinically Relevant Anticholinergic Effects: May enhance the adverse/toxic effect of other Agents with Clinically Relevant Anticholinergic Effects. Risk C: Monitor therapy
Alcohol (Ethyl): May enhance the CNS depressant effect of Orphenadrine. Risk X: Avoid combination
Alizapride: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Amantadine: May enhance the anticholinergic effect of Agents with Clinically Relevant Anticholinergic Effects. Risk C: Monitor therapy
Azelastine (Nasal): May enhance the CNS depressant effect of CNS Depressants. Risk X: Avoid combination
Botulinum Toxin-Containing Products: May enhance the anticholinergic effect of Agents with Clinically Relevant Anticholinergic Effects. Risk C: 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. Risk C: Monitor therapy
Brimonidine (Topical): May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Bromopride: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Bromperidol: May enhance the CNS depressant effect of CNS Depressants. Risk X: Avoid combination
Cannabinoid-Containing Products: Agents with Clinically Relevant Anticholinergic Effects may enhance the tachycardic effect of Cannabinoid-Containing Products. Risk C: Monitor therapy
Cannabinoid-Containing Products: CNS Depressants may enhance the CNS depressant effect of Cannabinoid-Containing Products. Risk C: Monitor therapy
Chlorphenesin Carbamate: May enhance the adverse/toxic effect of CNS Depressants. Risk C: Monitor therapy
Cimetropium: Agents with Clinically Relevant Anticholinergic Effects may enhance the anticholinergic effect of Cimetropium. Risk X: Avoid combination
CNS Depressants: May enhance the CNS depressant effect of Orphenadrine. Risk X: Avoid combination
DexmedeTOMIDine: CNS Depressants may enhance the CNS depressant effect of DexmedeTOMIDine. Management: Monitor for increased CNS depression during coadministration of dexmedetomidine and CNS depressants, and consider dose reductions of either agent to avoid excessive CNS depression. Risk D: Consider therapy modification
Difelikefalin: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Dimethindene (Topical): May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Eluxadoline: Agents with Clinically Relevant Anticholinergic Effects may enhance the constipating effect of Eluxadoline. Risk X: Avoid combination
Flunarizine: CNS Depressants may enhance the CNS depressant effect of Flunarizine. Risk X: Avoid combination
Gastrointestinal Agents (Prokinetic): Agents with Clinically Relevant Anticholinergic Effects may diminish the therapeutic effect of Gastrointestinal Agents (Prokinetic). Risk C: Monitor therapy
Glucagon: Agents with Clinically Relevant Anticholinergic Effects may enhance the adverse/toxic effect of Glucagon. Specifically, the risk of gastrointestinal adverse effects may be increased. Risk C: Monitor therapy
Glycopyrrolate (Oral Inhalation): Agents with Clinically Relevant Anticholinergic Effects may enhance the anticholinergic effect of Glycopyrrolate (Oral Inhalation). Risk X: Avoid combination
Glycopyrronium (Topical): May enhance the anticholinergic effect of Agents with Clinically Relevant Anticholinergic Effects. Risk X: Avoid combination
Ipratropium (Nasal): May enhance the anticholinergic effect of Agents with Clinically Relevant Anticholinergic Effects. Risk C: Monitor therapy
Ipratropium (Oral Inhalation): May enhance the anticholinergic effect of Agents with Clinically Relevant Anticholinergic Effects. Risk X: Avoid combination
Itopride: Agents with Clinically Relevant Anticholinergic Effects may diminish the therapeutic effect of Itopride. Risk C: Monitor therapy
Ixabepilone: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Kava Kava: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Kratom: May enhance the CNS depressant effect of CNS Depressants. Risk X: Avoid combination
Levosulpiride: Agents with Clinically Relevant Anticholinergic Effects may diminish the therapeutic effect of Levosulpiride. Risk X: Avoid combination
Lisuride: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Lofexidine: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Magnesium Sulfate: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Metoclopramide: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
MetyroSINE: CNS Depressants may enhance the sedative effect of MetyroSINE. Risk C: Monitor therapy
Minocycline (Systemic): May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Mirabegron: Agents with Clinically Relevant Anticholinergic Effects may enhance the adverse/toxic effect of Mirabegron. Risk C: Monitor therapy
Nabilone: May enhance the CNS depressant effect of CNS Depressants. Risk X: Avoid combination
Nitroglycerin: Agents with Clinically Relevant Anticholinergic Effects may decrease the absorption of Nitroglycerin. Specifically, anticholinergic agents may decrease the dissolution of sublingual nitroglycerin tablets, possibly impairing or slowing nitroglycerin absorption. Risk C: Monitor therapy
Olopatadine (Nasal): May enhance the CNS depressant effect of CNS Depressants. Risk X: Avoid combination
Oxatomide: May enhance the anticholinergic effect of Agents with Clinically Relevant Anticholinergic Effects. Risk X: Avoid combination
Oxomemazine: May enhance the CNS depressant effect of CNS Depressants. Risk X: Avoid combination
Paraldehyde: CNS Depressants may enhance the CNS depressant effect of Paraldehyde. Risk X: Avoid combination
Piribedil: CNS Depressants may enhance the CNS depressant effect of Piribedil. Risk C: Monitor therapy
Potassium Chloride: Agents with Clinically Relevant Anticholinergic Effects 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. Risk X: Avoid combination
Potassium Citrate: Agents with Clinically Relevant Anticholinergic Effects may enhance the ulcerogenic effect of Potassium Citrate. Management: Patients on drugs with substantial anticholinergic effects should avoid using any solid oral dosage form of potassium citrate. Risk X: Avoid combination
Pramipexole: CNS Depressants may enhance the sedative effect of Pramipexole. Risk C: Monitor therapy
Pramlintide: May enhance the anticholinergic effect of Agents with Clinically Relevant Anticholinergic Effects. These effects are specific to the GI tract. Risk X: Avoid combination
Procarbazine: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
QuiNIDine: May enhance the anticholinergic effect of Agents with Clinically Relevant Anticholinergic Effects. Risk C: Monitor therapy
Ramosetron: Agents with Clinically Relevant Anticholinergic Effects may enhance the constipating effect of Ramosetron. Risk C: Monitor therapy
Revefenacin: Agents with Clinically Relevant Anticholinergic Effects may enhance the anticholinergic effect of Revefenacin. Risk X: Avoid combination
Rivastigmine: Agents with Clinically Relevant Anticholinergic Effects may diminish the therapeutic effect of Rivastigmine. Rivastigmine may diminish the therapeutic effect of Agents with Clinically Relevant Anticholinergic Effects. Management: Use of rivastigmine with an anticholinergic agent is not recommended unless clinically necessary. If the combination is necessary, monitor for reduced anticholinergic effects. Risk D: Consider therapy modification
Ropeginterferon Alfa-2b: CNS Depressants may enhance the adverse/toxic effect of Ropeginterferon Alfa-2b. Specifically, the risk of neuropsychiatric adverse effects may be increased. Management: Avoid coadministration of ropeginterferon alfa-2b and other CNS depressants. If this combination cannot be avoided, monitor patients for neuropsychiatric adverse effects (eg, depression, suicidal ideation, aggression, mania). Risk D: Consider therapy modification
ROPINIRole: CNS Depressants may enhance the sedative effect of ROPINIRole. Risk C: Monitor therapy
Rotigotine: CNS Depressants may enhance the sedative effect of Rotigotine. Risk C: Monitor therapy
Rufinamide: May enhance the adverse/toxic effect of CNS Depressants. Specifically, sleepiness and dizziness may be enhanced. Risk C: Monitor therapy
Secretin: Agents with Clinically Relevant Anticholinergic Effects 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. Risk D: Consider therapy modification
Thalidomide: CNS Depressants may enhance the CNS depressant effect of Thalidomide. Risk X: Avoid combination
Thiazide and Thiazide-Like Diuretics: Agents with Clinically Relevant Anticholinergic Effects may increase the serum concentration of Thiazide and Thiazide-Like Diuretics. Risk C: Monitor therapy
Tiotropium: Agents with Clinically Relevant Anticholinergic Effects may enhance the anticholinergic effect of Tiotropium. Risk X: 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. Risk D: Consider therapy modification
Umeclidinium: May enhance the anticholinergic effect of Agents with Clinically Relevant Anticholinergic Effects. Risk X: Avoid combination
Valerian: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Animal reproduction studies have not been conducted.
As an antihistamine, anticholinergic, and NMDA receptor antagonist, the exact mechanism of action in musculoskeletal pain is unknown, but may be related to analgesic properties. Orphenadrine does not directly relax skeletal muscles (Cheah 2020; manufacturer's labeling).
Onset of effect: Peak effect: Oral: 2 to 4 hours
Duration: 4 to 6 hours
Protein binding: 20%
Metabolism: Extensively hepatic
Half-life elimination: 14 to 16 hours
Excretion: Primarily urine (8% as unchanged drug)
Do you want to add Medilib to your home screen?