Orphenadrine


Concise Prescribing Info
Indications/Uses
Listed in Dosage.
Dosage/Direction for Use
Adult : PO Muscle spasms As orphenadrine citrate: 100 mg twice daily. Parkinsonism As orphenadrine HCl: Initial: 150 mg daily in divided doses, increased by 50 mg every 2-3 days according to response. Usual maintenance dose: 150-300 mg daily. Max: 400 mg daily in divided doses. IV/IM Muscle spasms As orphenadrine citrate: 60 mg every 12 hr by IM or slow IV inj.
Dosage Details
Oral
Parkinsonism
Adult: As orphenadrine HCl: Initially, 150 mg daily in divided doses, increased by 50 mg every 2-3 days according to response. Usual maintenance dose: 150-300 mg daily. Max: 400 mg daily in divided doses.

Oral
Muscle spasms
Adult: As orphenadrine citrate: 100 mg twice daily.

Parenteral
Muscle spasms
Adult: As orphenadrine citrate: 60 mg every 12 hr by IM or slow IV inj.
Administration
May be taken with or without food. May be taken w/ meals if GI upset occurs.
Contraindications
Prostatic hypertrophy, tardive dyskinesia, porphyria, urinary retention, paralytic ileus, pyloric stenosis, glaucoma, risk of developing hyperpyrexia, cardiospasm, and myasthenia gravis.
Special Precautions
Patient w/ conditions characterized by tachycardia (e.g heart failure, thyrotoxicosis); cardiac arrhythmias, HTN, cardiac impairment, coronary insufficiency, micturition difficulties, history of drug abuse, acute alcoholism. Avoid abrupt withdrawal. Renal and hepatic impairment. Pregnancy and lactation.
Adverse Reactions
Significant: CNS depression, tachycardia, euphoria, potential for abuse, increased intraocular pressure, GI obstruction, skeletal muscle pain/spasm.
Nervous: Dizziness, drowsiness, restlessness, sedation, confusion, nervousness, hallucinations, convulsions, insomnia, coordination disturbances, light-headedness, headache, agitation, tremor, weakness.
CV: Palpitation.
GI:Dry mouth, nausea, vomiting, GI disturbances, constipation, gastric irritation.
Resp:Nasal congestion.
Genitourinary: Urinary retention/hesitancy.
Ophthalmologic: Accommodation disorders, blurred vision, nystagmus, dilatation of pupils.
Dermatologic: Pruritus, urticaria.
IM/IV/Parenteral/PO: C
Patient Counseling Information
This drug may cause dizziness, drowsiness, slight euphoria or blurred vision, if affected, do not drive or operate machineries.
Overdosage
Symptoms: Nausea, vomiting, flushing, dilated pupils, dry mouth and tongue, hot dry skin, fever, sinus tachycardia, HTN, ataxia, nystagmus, drowsiness, delirium, agitation and visual hallucinations. Management: Supportive treatment. Administer activated charcoal or gastric lavage w/in 1 hr of ingestion. Establish patent airway and provide oxygen or ventilation to correct hypoxia or hypercapnoea. Monitor body temp. Convulsions or delirium can be treated w/diazepam. Maintain BP, may give intravascular vol expanders, adrenaline, dopamine, dobutamine if necessary. Administer Na bicarbonate for cardiac dysrhythmias.
Drug Interactions
Increased anti-muscarinic effects (e.g. risk of severe constipation, ileus, atropine-like psychoses and heat stroke) w/ anticholinergic drugs, antihistamines, antispasmodics, tricyclic antidepressants, phenothiazines, dopaminergic anti-parkinsonian drugs (e.g. amantadine) and anti-arrhythmics (e.g. disopyramide). May cause confusion, anxiety and tremors w/ propoxyphene. May cause skeletal muscle spasms/pain w/ analgesics.
Action
Description: Orphenadrine is a tertiary amine antimuscarinic which exerts antiparkinsonian action by inhibiting excess central cholinergic effects that occur due to dopamine deficiency. It reduces muscle spasms possibly by its atropine-like effect on the medulla or on cerebral motor centers.
Onset: 2-4 hr (oral).
Duration: Reduction of muscle spasms: 4-6 hr.
Pharmacokinetics:
Absorption: Readily absorbed from the GI tract.
Distribution: Plasma protein binding: 20%.
Metabolism: Almost completely metabolised in the liver into at least 8 metabolites.
Excretion: Via urine (as metabolites, 8% as unchanged drug). Elimination half-life: 14-16 hr.
Chemical Structure

Chemical Structure Image
Orphenadrine

Source: National Center for Biotechnology Information. PubChem Database. Orphenadrine, CID=4601, https://pubchem.ncbi.nlm.nih.gov/compound/Orphenadrine (accessed on Jan. 22, 2020)

Storage
Store between 20-25°C.
ATC Classification
N04AB02 - orphenadrine (chloride) ; Belongs to the class of anticholinergic agents, ethers chemically close to antihistamines. Used in the management of Parkinson's disease.
References
Anon. Orphenadrine. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 24/08/2017.

Buckingham R (ed). Orphenadrine Citrate. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 24/08/2017.

Joint Formulary Committee. Orphenadrine Hydrochloride. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 24/08/2017.

McEvoy GK, Snow EK, Miller J et al (eds). Orphenadrine Citrate. AHFS Drug Information (AHFS DI) [online]. American Society of Health-System Pharmacists (ASHP). https://www.medicinescomplete.com.. Accessed 24/08/2017.

Orphenadrine Citrate Extended-Release Tablets, USP (Carilion Materials Management). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 24/08/2017.

Orphenadrine Citrate Injection, USP (Akorn, Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 25/08/2017.

Disclaimer: This information is independently developed by MIMS based on Orphenadrine from various references and is provided for your reference only. Therapeutic uses, prescribing information and product availability may vary between countries. Please refer to MIMS Product Monographs for specific and locally approved prescribing information. Although great effort has been made to ensure content accuracy, MIMS shall not be held responsible or liable for any claims or damages arising from the use or misuse of the information contained herein, its contents or omissions, or otherwise. Copyright © 2020 MIMS. All rights reserved. Powered by MIMS.com
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