Carbidopa + levodopa + entacapone


Full Prescribing Info
Dosage/Direction for Use

Oral
Parkinson's disease and "end of dose" motor fluctuations
Adult: Each tab contains levodopa and carbidopa in a ratio of 4:1 and entacapone 200 mg: 1 tab at each dose. Max: 8 tab daily. Doses are individualised based on therapeutic response; may be adjusted by changing strength or adjusting interval. Patients previously treated w/ carbidopa/levodopa immediate-release tab (1:4 ratio): W/ current entacapone therapy: May switch directly to corresponding strength or slightly higher dose of combination tab. W/o entacapone therapy: May switch directly to corresponding strength or slightly lower dose of levodopa; patients taking levodopa doses >800 mg daily or w/ dyskinesia should start on a separate entacapone therapy before switching to the combination preparation, w/ 10-30% reduction in levodopa dose.
Hepatic impairment:
Severe: Contraindicated.
Administration
May be taken with or without food. Keep a consistent diet. A change in diet to foods high in protein may delay levodopa absorption & reduce amount taken up in circulation. Excessive acidity also delays stomach emptying & thus delays levodopa absorption. Fe salts (eg in multivit prep) may also reduce amount of levodopa available to the body.
Contraindications
Narrow-angle glaucoma, phaeochromocytoma, history of neuroleptic malignant syndrome (NMS) and/or non-traumatic rhabdomyolysis. Severe hepatic impairment. Concurrent use of or w/in 14 days of discontinuing non-selective MAOIs.
Special Precautions
Patient w/ ischaemic heart disease, severe CV or pulmonary disease, bronchial asthma, endocrine disease, chronic wide-angle glaucoma, biliary obstruction; history of peptic ulcer disease, convulsions, MI w/ residual atrial nodal or ventricular arrhythmias; past or current psychoses. Avoid abrupt withdrawal or dose reduction. Mild to moderate hepatic and severe renal impairment. Patient Counselling This drug may cause dark discolouration of urine, saliva or sweat. May cause dizziness and symptomatic orthostatism, if affected, do not drive or operate machinery. Monitoring Parameters Monitor hepatic, renal and cardiac functions; BP, mental status, serum Fe, wt loss, fibrotic complications, intraocular pressure; signs/symptoms of Parkinson's disease, neuroleptic malignant syndrome (during abrupt discontinuation), excessive drowsiness, depression. Perform regular dermatologic examination during therapy.
Adverse Reactions
Hypotension, orthostatic hypotension, syncope, dyskinesia, depression, hallucinations, impulse control/compulsive behaviour, diarrhoea, somnolence, urine discolouration, nausea, vomiting, abdominal pain, dry mouth.
Potentially Fatal: Hyperpyrexia and confusion resembling neuroleptic malignant syndrome (during dose reduction or withdrawal); severe rhabdomyolysis.
Overdosage
Symptoms: Confusional state, agitation, bradycardia, ventricular tachycardia, Cheyne-Stokes respiration, coma; skin, tongue, conjunctiva and urine discolouration. Management: General supportive measures w/ immediate gastric lavage and repeated doses of charcoal. Appropriate anti-arrhythmic therapy may be given as required.
Drug Interactions
Increased heart rate and/or BP, arrhythmia w/ drugs metabolised by COMT. Risk of retroperitoneal fibrosis, pulmonary infiltrates, pleural effusion and thickening w/ ergot derived dopaminergic agents. Risk of symptomatic postural hypotension w/ antihypertensive agents. Dopamine D2 receptor antagonists (e.g. metoclopramide) and isoniazid may reduce the therapeutic effect of levodopa. Phenytoin and papaverine may reverse the effect of levodopa. Formation of chelates w/ Fe salts.
Potentially Fatal: Risk of increased adrenergic tone w/ non-selective MAOIs (e.g. phenelzine, tranylcypromine).
Food Interaction
Impaired absorption w/ high protein diet. May enhance the sedative effect of alcohol.
Lab Interference
False-negative reaction in glucose-oxidase tests for glucosuria. False-positive urine ketones. False diagnosis for phaeochromocytoma based on urine levels of catecholamine.
Action
Levodopa is the metabolic precursor of dopamine. It crosses the blood-brain barrier and is converted to dopamine in the brain. Carbidopa increases the amount of levodopa that is transported into the CNS by inhibiting the decarboxylation of peripheral levodopa. Entacapone is a selective inhibitor of COMT which alters the pharmacokinetics of levodopa, resulting to increased and more sustained levodopa serum levels.
Absorption: Carbidopa: Rapidly but incompletely absorbed from the GI tract. Levodopa: Rapidly absorbed from the GI tract. Time to peak plasma concentration: W/in 2 hr. Entacapone: Bioavailability: Approx 35%. Time to peak plasma concentration: Approx 1 hr. Impaired absorption w/ high protein diet.
Distribution: Levodopa: Crosses the blood-brain barrier and placenta; enters breast milk. Plasma protein binding: Approx 98% (entacapone); approx 10-30% (levodopa).
Metabolism: Levodopa: Rapidly metabolised to dihydroxyphenylacetic acid and homovanillic acid via decarboxylation by aromatic L-amino acid enzyme; other routes include O-methylation, transamination and oxidation. Entacapone: Undergoes extensive first-pass metabolism.
Excretion: Carbidopa: Via urine, as unchanged drug and metabolites. Levodopa: Via urine (approx 80%); faeces (small amounts). Elimination half-life: Approx 30-60 min. Entacapone: Mainly via faeces; urine (approx 10-20%, mainly as glucuronide conjugates).
Storage
Oral: Store at 25°C.
ATC Classification
N04BA01 - levodopa ; Belongs to the class of dopa and dopa derivative dopaminergic agents. Used in the management of Parkinson's disease.
N04BX02 - entacapone ; Belongs to the class of other dopaminergic agents used in the management of Parkinson's disease.
Disclaimer: This information is independently developed by CIMS based on carbidopa + levodopa + entacapone from various references and is provided for your reference only. Therapeutic uses, prescribing information and product availability may vary between countries. Please refer to CIMS Product Monographs for specific and locally approved prescribing information. Although great effort has been made to ensure content accuracy, CIMS 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 CIMS. All rights reserved. Powered by CIMSAsia.com
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