Adult: As orphenadrine hydrochloride: Initially, 150 mg daily in divided doses, gradually increase by 50 mg every 2-3 days until maximum benefits is attained. Usual maintenance dose: 150-300 mg daily. Max: 400 mg daily in divided doses. Elderly: Dose reduction may be required.
Oral Painful muscle spasm associated with musculoskeletal conditions
Adult: As orphenadrine citrate: 100 mg bid. Elderly: Dose reduction may be required.
May be taken with or without food. May be taken w/ meals if GI upset occurs.
Patient with CV disease (e.g. heart failure, cardiac decompensation, coronary insufficiency, tachycardia, cardiac arrhythmias), thyrotoxicosis, hypertension, history of drug abuse or acute alcoholism, porphyria, micturition difficulties. Avoid abrupt withdrawal. Some products or formulations are not interchangeable; refer to specific product guideline for further information. Renal and hepatic impairment. Elderly. Pregnancy and lactation.
Significant: CNS depression, euphoria (increased risk for drug abuse and dependence). Blood and lymphatic system disorders: Very rarely, aplastic anaemia. Cardiac disorders: Palpitation, tachycardia. Eye disorders: Disturbance of visual accommodation. Gastrointestinal disorders: Dry mouth, gastrointestinal disturbances, nausea, constipation. Immune system disorders: Hypersensitivity reaction. Rarely, anaphylaxis (IM). Nervous system disorders: Dizziness, drowsiness, restlessness. Psychiatric disorders: Confusion, hallucination. Renal and urinary disorders: Micturition difficulties.
This drug may cause blurred vision, dizziness or slight euphoria, if affected, do not drive or operate machinery.
If for prolonged use, monitor blood, urine, and LFTs.
Symptoms: Nausea, vomiting, flushing, dilated pupils, dry mouth and tongue, hot dry skin, fever, hypertension, sinus tachycardia, ataxia, nystagmus, drowsiness, delirium, agitation and visual hallucinations. Management: Administer activated charcoal or perform gastric lavage within 1 hour of ingestion. Establish patient airway and provide oxygen or ventilation to correct hypoxia or hypercapnia; administer intravascular volume expander or dopamine for hypo- or hyperthermia, hypotension; treat skin blisters as burns; administer diazepam for convulsions or delirium. Administer Na bicarbonate (even in the absence of acidosis) and correct hypoxia for cardiac dysrhythmias.
May enhance the sedative effect with other sedatives. May cause anxiety, confusion, tremors with propoxyphene. May increase the antimuscarinic effects with antihistamines, antispasmodics, TCAs, phenothiazines, dopaminergic antiparkinsonian drugs (e.g. amantadine), antiarrhythmics (e.g. disopyramide). Enhanced effect with anticholinergic drugs.
Alcohol may potentiate the CNS depressant effect of this drug.
Description: Orphenadrine, a tertiary amine antimuscarinic, is an indirect skeletal muscle relaxant that is believed to work by central atropine-like effects. Additionally, it has weak antihistaminic and local anaesthetic properties. Onset: 2-4 hours (oral). Duration: 4-6 hours. Pharmacokinetics: Absorption: Readily absorbed from the gastrointestinal tract and after an IM inj. Distribution: Rapidly distributed to tissues. Plasma protein binding: 20% Metabolism: Extensively metabolised in the liver into approx 8 metabolites. Excretion: Mainly via urine (8% as unchanged drug). Elimination half-life: 14-16 hours.
Store below 30°C. Protect from light, moisture, and heat.