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