Entacapone

Oral
Adjunct to levodopa treatment in Parkinson's disease

Contraindicated.

May be taken with or without food.

Phaeochromocytoma, history of neuroleptic malignant syndrome and/or non-traumatic rhabdomyolysis. Hepatic impairment. Concomitant use w/ non-selective MAOIs.

Patient w/ biliary obstruction, ischaemic heart disease. Avoid abrupt withdrawal. Pregnancy and lactation.

Abdominal pain, nausea, vomiting, diarrhoea, constipation, colitis, dry mouth, dyskinesia, dizziness, nightmares, insomnia, hallucinations, confusion, fatigue, increased sweating, behavioural disturbances; urine, skin, hair, beard and nail discolourations; cholestatic hepatitis, rhabdomyolysis. Rarely, agitation, urticaria, erythematous or maculopapular rash, anorexia, wt decrease, increased liver enzymes.
Potentially Fatal: Neuroleptic malignant syndrome (NMS)-like syndrome (w/ abrupt reduction or withdrawal).

PO: C

This drug may cause reddish-brown discolouration of urine. When given w/ levodopa, may cause dizziness and symptomatic orthostatism, if affected, do not drive or operate machinery.

Monitor BP, hepatic function, mental status and impulse control disorders, daytime sleepiness, serum Fe, wt loss; signs/symptoms of Parkinson's disease, neuroleptic malignant syndrome (if abrupt withdrawal is required); regular dermatologic examination.

Symptoms: Decreased activity, confusion, somnolence, hypotonia, urticaria, skin discolouration. Management: Symptomatic treatment.

May interfere w/ metabolism of other drugs metabolised by COMT (e.g. rimiterole). May aggravate levodopa-induced orthostatic hypotension. Risk of dopaminergic effects w/ dopamine agonists (e.g. bromocriptine), selegiline, amantadine. May form chelates w/ Fe in the GI tract. Additive sedative effects w/ other CNS depressants.
Potentially Fatal: Concomitant use w/ non-selective MAOIs (e.g. phenelzine) may result in inhibition of principal pathways in the metabolism of catecholamines.

May potentiate the sedative effect of alcohol.

Description:
Mechanism of Action: Entacapone decreases the metabolic loss of levodopa to 3-O-methyldopa (3-OMD) through inhibition of COMT enzyme leading to an increased levodopa concentration, thus, extending the duration and effect in the brain.
Pharmacokinetics:
Absorption: Rapidly absorbed from the GI tract. Bioavailability: 29-46%. Time to peak plasma concentration: Approx 1 hr.
Distribution: Plasma protein binding: Approx 98% (primarily to albumin).
Metabolism: Undergoes extensive first-pass metabolism; isomerisation to the cis-isomer, followed by direct glucuronidation of the parent and cis-isomer.
Excretion: Mainly via faeces (10%); urine (approx 10-20%, as glucuronide conjugates). Elimination half-life: Approx 1.6-3.4 hr.

Source: National Center for Biotechnology Information. PubChem Database. Entacapone, CID=5281081, https://pubchem.ncbi.nlm.nih.gov/compound/Entacapone (accessed on Jan. 21, 2020)

Store at 25°C.

Antiparkinsonian Drugs

N04BX02 - entacapone ; Belongs to the class of other dopaminergic agents used in the management of Parkinson's disease.

Anon. Entacapone. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 27/11/2015.

Buckingham R (ed). Entacapone. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 27/11/2015.

Comtan Tablet, Film Coated (Novartis Pharmaceuticals Corporation). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 27/11/2015.

McEvoy GK, Snow EK, Miller J et al (eds). Entacapone. AHFS Drug Information (AHFS DI) [online]. American Society of Health-System Pharmacists (ASHP). https://www.medicinescomplete.com. Accessed 27/11/2015.