Orphenadrine

Oral
Parkinsonism

Oral
Muscle spasms

Parenteral
Muscle spasms

May be taken with or without food. May be taken w/ meals if GI upset occurs.

Prostatic hypertrophy, tardive dyskinesia, porphyria, urinary retention, paralytic ileus, pyloric stenosis, glaucoma, risk of developing hyperpyrexia, cardiospasm, and myasthenia gravis.

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.

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

This drug may cause dizziness, drowsiness, slight euphoria or blurred vision, if affected, do not drive or operate machineries.

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.

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.

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.

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

Store between 20-25°C.

Antiparkinsonian Drugs / Muscle Relaxants

N04AB02 - orphenadrine (chloride) ; Belongs to the class of anticholinergic agents, ethers chemically close to antihistamines. Used in the management of Parkinson's disease.

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.