Donepezil: Indication, Dosage, Side Effect, Precaution

Concise Prescribing Info Patient Medicine Information

Concise Prescribing Info

Indications/Uses

Mild to moderately severe dementia in Alzheimer's disease.

Dosage/Direction for Use

Adult : PO Initial: 5 mg once daily at bedtime, may increase to 10 mg once daily after 1 mth, if needed.

Dosage Details

Oral
Mild dementia in Alzheimer's disease, Moderate dementia in Alzheimer's disease, Severe dementia in Alzheimer's disease

Adult: Initially, 5 mg once daily at bedtime, may increase after 1 mth to 10 mg once daily, if necessary. Max: 10 mg daily.
Elderly: Initially, 5 mg daily at bedtime, increase if necessary up to 10 mg once daily at bedtime after 4-6 wk.

Administration

May be taken with or without food.

Special Precautions

Patient w/ history of asthma or COPD, sick sinus syndrome, supraventricular conduction abnormalities, susceptibility to peptic ulcer, seizures, GI or urinary tract obstruction. Hepatic impairment. Pregnancy and lactation.

Adverse Reactions

Diarrhoea, muscle cramps, fatigue, nausea, vomiting, headache, insomnia, abnormal dreams, common cold, aggression, agitation, anorexia, dizziness, hallucinations, pruritus, rash, syncope, urinary incontinence, bradycardia, duodenal/gastric ulcers, GI haemorrhage, seizures. Rarely, AV block, extrapyramidal symptoms, hepatitis, bladder outflow obstruction, sino-atrial block.
Potentially Fatal: Rarely, neuroleptic malignant syndrome.

Pregnancy Category (US FDA)

PO: C

Patient Counseling Information

May impair ability to drive or operate machinery.

MonitoringParameters

Monitor mental status, wt, pulse, symptoms of GI intolerance or bleeding.

Overdosage

Symptoms: Cholinergic crisis characterised by severe nausea, vomiting, salivations, sweating, bradycardia, hypotension, resp depression, collapse, convulsion, muscle weakness. Management: Supportive treatment and use of anticholinergic such as IV atropine.

Drug Interactions

Increased risk of neuroleptic malignant syndrome w/ antipsychotics. Synergistic effect w/ succinylcholine, similar neuromuscular blocking agents, or cholinergic agonists (e.g. bethanechol). May interfere w/ the activity of anticholinergic medications. Increased plasma concentration when used w/ CYP3A4 inhibitors (e.g. ketoconazole, erythromycin) and CYP 2D6 inhibitors (e.g. fluoxetine, quinidine). Decreased plasma concentrations w/ enzyme inducers (e.g. rifampicin, phenytoin).

Action

Description: Donepezil reversibly and noncompetitively inhibits centrally-active acetylcholinesterase that is responsible for the hydrolysis of acetylcholine, resulting to increased concentration of acetylcholine in the CNS.
Pharmacokinetics:
Absorption: Well absorbed from the GI tract. Time to peak plasma concentration: 3-4 hr.
Distribution: Volume of distribution: 12-16 L/kg. Protein binding: Approx 96% (to albumin (75%) and α1-acid glycoprotein (21%).
Metabolism: Extensively metabolised in the liver, mainly by CYP3A4 isoenzyme and to a lesser extent by CYP2D6, into 4 major metabolites.
Excretion: Via urine (57%, as unchanged drug and metabolites) and faeces (15%). Elimination half-life: Approx 70 hr.

Chemical Structure

Storage

Store between 15-30°C.

MIMS Class

Neurodegenerative Disease Drugs

ATC Classification

N06DA02 - donepezil ; Belongs to the class of anticholinesterases. Used in the management of dementia.

References

Anon. Donepezil. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 09/11/2016.

Aricept Solution (Eisai Inc). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 09/11/2016.

Buckingham R (ed). Donepezil Hydrochloride. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com . Accessed 09/11/2016.

Donepezil Hydrochloride 5 mg and 10 mg Tablet, Film Coated (Major Pharmaceuticals). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 09/11/2016.

Donepezil Hydrochloride Tablet, Film Coated (Camber Pharmaceuticals, Inc). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 09/11/2016.

Joint Formulary Committee. Donepezil hydrochloride. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 09/11/2016.

McEvoy GK, Snow EK, Miller J et al (eds). Donepezil Hydrochloride. AHFS Drug Information (AHFS DI) [online]. American Society of Health-System Pharmacists (ASHP). https://www.medicinescomplete.com. Accessed 09/11/2016.

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