Galantamine


Concise Prescribing Info
Indications/Uses
Dementia in Alzheimer's disease.
Dosage/Direction for Use
Adult : PO For symptomatic treatment of mild to moderately severe cases: As conventional tab/oral susp: Initially, 4 mg bid for 4 weeks, increase to 8 mg bid for at least 4 weeks, if tolerated. May further increase to 12 mg bid according to individual response and tolerability. As modified-release cap: Initially, 8 mg once daily, preferably in the morning for 4 weeks, increase to 16 mg once daily for at least 4 weeks. May further increase to 24 mg once daily according to individual response and tolerability. Reassess dosing, clinical benefit and individual tolerance within the 1st 3 months of treatment and regularly thereafter.
Dosage Details
Oral
Alzheimer's dementia
Adult: For symptomatic treatment of mild to moderately severe cases: As conventional tab/oral susp: Initially, 4 mg bid for 4 weeks, increase to 8 mg bid for at least 4 weeks, if tolerated. May further increase to 12 mg bid according to individual response and tolerability. As modified-release cap: Initially, 8 mg once daily, preferably in the morning for 4 weeks, increase to 16 mg once daily for at least 4 weeks. May further increase to 24 mg once daily according to individual response and tolerability. Reassess dosing, clinical benefit and individual tolerance within the 1st 3 months of treatment and regularly thereafter.
Special Patient Group
Patients taking potent CYP2D6 or CYP3A4 inhibitors: Reduced maintenance dose may be considered according to tolerability.

Pharmacogenomics:

Galantamine is primarily metabolised by CYP2D6 and CYP3A4 isoenzymes to inactive metabolites. Individuals with reduced CYP2D6 activity, known as CYP2D6 poor metabolisers, may experience an increased galantamine exposure. The prevalence of CYP2D6 poor metabolisers is estimated at approx 7% of the normal population.

CYP2D6 poor metabolisers
Patient may experience increased galantamine exposure. Although results of researches indicate an increased exposure, CYP2D6 poor metabolisers do not require dosage adjustments since the galantamine dose is titrated according to individual tolerability.

Pharmacogenetic testing prior to galantamine treatment initiation has not been addressed by currently available references.
Renal Impairment
CrCl (mL/min) Dosage
<9 Contraindicated.
Hepatic Impairment
Moderate (Child-Pugh score 7-9): As conventional tab, oral susp: Initially, 4 mg once daily for at least 1 week, then increased to 4 mg bid for at least 4 weeks. Max: 8 mg bid. As modified-release cap: Initially, 8 mg every other day for 1 week, then increased to 8 mg once daily for 4 weeks. Max: 16 mg daily. Doses are given preferably in the morning. Severe (Child-Pugh score >9): Contraindicated.
Administration
Should be taken with food.
Contraindications
Severe renal and hepatic impairment.
Special Precautions
Patient with CV disease (e.g. immediate post-MI period, new-onset atrial fibrillation, 2nd degree heart block or greater, unstable angina pectoris, CHF, sick sinus syndrome, bradycardia, or other supraventricular cardiac conduction abnormalities); uncorrected electrolyte disturbances (e.g. hyper- or hypokalaemia); history of seizure disorders; Parkinson’s disease; asthma, COPD, active pulmonary infections (e.g. pneumonia); bladder outlet obstruction or prostatic hyperplasia; gastrointestinal obstruction or recovering from gastrointestinal surgery; risk factors for ulcer disease (e.g. history of ulcer, concomitant NSAID use). Moderate renal and mild to moderate hepatic impairment. Elderly. Pregnancy and lactation. CYP2D6 poor metabolisers.
Adverse Reactions
Significant: Serious skin reactions (e.g. Stevens-Johnson syndrome, acute generalised exanthematous pustulosis, erythema multiforme), CNS depression, vagotonic effects on heart rate (e.g. bradycardia, atrioventricular node block), weight loss, seizures, increase gastric acid secretion, bladder outflow obstruction, BPH symptoms exacerbation.
Cardiac disorders: Palpitations.
Ear and labyrinth disorders: Tinnitus.
Eye disorders: Blurred vision.
Gastrointestinal disorders: Nausea, vomiting, abdominal pain, diarrhoea, dyspepsia.
General disorders and admin site conditions: Fatigue, asthenia, malaise, lethargy.
Injury, poisoning and procedural complications: Fall, laceration.
Investigations: Increased hepatic enzymes.
Metabolism and nutrition disorders: Decreased appetite, dehydration.
Musculoskeletal and connective tissue disorders: Muscle spasms, muscle weakness.
Nervous system disorders: Headache, dizziness, somnolence, syncope, tremor.
Psychiatric disorders: Depression, hallucination.
Skin and subcutaneous tissue disorders: Hyperhidrosis.
Vascular disorders: Hypertension, flushing.
Patient Counseling Information
This drug may cause dizziness and somnolence, if affected, do not drive or operate machinery. Drink adequate amount of fluids during your treatment with this medicine.
MonitoringParameters
Monitor body weight; mental status; symptoms of active or occult gastrointestinal bleeding, gastrointestinal intolerance, and cholinergic crisis.
Overdosage
Symptoms: Muscle weakness or fasciculations, severe nausea, vomiting, gastrointestinal cramping, salivation, lacrimation, urination, defaecation, sweating, bradycardia, hypotension, collapse and convulsions. Increasing muscle weakness with tracheal hypersecretion and bronchospasms may lead to compromised vital airways. Management: Symptomatic and supportive treatment. May administer atropine for severe cases at initial dose of 0.5-1 mg via IV inj, then adjust subsequent doses according to response.
Drug Interactions
Increased bioavailability and risk of cholinergic adverse effects with potent CYP2D6 inhibitors (e.g. quinidine, paroxetine, fluoxetine); and CYP3A4 inhibitors (e.g. ketoconazole, ritonavir, erythromycin). Additive effects with other cholinomimetics (e.g. ambenonium, donepezil, neostigmine, pyridostigmine, rivastigmine, systemic pilocarpine). May antagonise anticholinergic effects of atropine.
Food Interaction
Delay rate of absorption with food.
Action
Description: Galantamine is a selective, competitive and reversible centrally-acting acetylcholinesterase inhibitor. It elevates acetylcholine in the cerebral cortex by slowing its degradation. It also increases acetylcholine from surviving presynaptic terminals by modulating the nicotinic acetylcholine receptors. Glutamate and serotonin levels may also be increased.
Pharmacokinetics:
Absorption: Well absorbed from the gastrointestinal tract. Food delays rate of absorption. Bioavailability: Approx 90%. Time to peak plasma concentration: Approx 1 hour (immediate-release); approx 4.5-5 hours (modified-release).
Distribution: Volume of distribution: 175 L. Plasma protein binding: 18%.
Metabolism: Metabolised in the liver mainly by CYP2D6 isoenzyme and CYP3A4 isoenzyme to O-desmethyl-galantamine, and galantamine-N-oxide metabolites, respectively.
Excretion: Via urine (approx 20-30% as unchanged drug); faeces (approx 6%). Elimination half-life: Approx 7 hours.
Chemical Structure

Click on icon to see table/diagram/image
Storage
Tab/cap: Store at 25°C. Oral solution: Store between 20-25°C.
ATC Classification
N06DA04 - galantamine ; Belongs to the class of anticholinesterases. Used in the management of dementia.
Disclaimer: This information is independently developed by MIMS based on Galantamine from various references and is provided for your reference only. Therapeutic uses, prescribing information and product availability may vary between countries. Please refer to MIMS Product Monographs for specific and locally approved prescribing information. Although great effort has been made to ensure content accuracy, MIMS 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 MIMS. All rights reserved. Powered by MIMS.com
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