Tacrine


Concise Prescribing Info
Indications/Uses
Alzheimer's dementia.
Dosage/Direction for Use
Adult : PO Initial: 10 mg 4 times/day for at least 4 wk. May increase slowly. Max: 160 mg/day in 4 divided doses.
Dosage Details
Oral
Alzheimer's dementia
Adult: Initially, 10 mg 4 times daily for at least 4 wk. May be increased by 40 mg daily at 4-6 wkly intervals. Max: 160 mg/day in 4 divided doses.
Hepatic Impairment
Adjustment in tacrine dose in serum aminotransferase elevations: ≤2 times the upper limit of normal: Continue treatment. >2 but ≤3 times the upper limit of normal: Continue treatment but with wkly monitoring of LFT till levels return to normal. >3 times but ≤5 times the upper limit of normal: Reduce dose by 40 mg daily and monitor LFT wkly until levels return to within normal limits, after which resume usual dosage titration. >5 times the upper limit of normal: Withhold tacrine and monitor for signs and symptoms of hepatitis until LFT return to within normal limits, after which may consider rechallenge.
Administration
Should be taken on an empty stomach. Take 1 hr before or 2 hr after meals.
Contraindications
Hypersensitivity to tacrine or acridine derivatives. History of jaundice with tacrine therapy. Lactation.
Special Precautions
Monitor serum-alanine aminotransferase concentration. Avoid abrupt withdrawal or large dose reduction. Impaired liver function or history of liver function abnormalities, epilepsy, bronchial asthma, bradycardia, CV conduction disorders, GI or urinary tract obstruction, recent intestinal or bladder surgery, risk of peptic ulcer. Pregnancy. Smoking may reduce serum tacrine levels.
Adverse Reactions
Dizziness, headache, nausea, vomiting, diarrhoea, myalgia, ataxia.
Potentially Fatal: Hepatotoxicity.
Overdosage
Cholinergic crisis characterised by severe nausea, vomiting, salivation, sweating, bradycardia, hypotension, collapse, convulsions, and muscle weakness. May result in death if respiratory muscles are involved. General supportive treatment and IV atropine sulfate. Adults: Initial dose of 1-2 mg IV atropine with subsequent doses based on clinical response.
Drug Interactions
Increased serum tacrine levels with coadmin of cimetidine, fluvoxamine, quinolones and HRT. Increased theophylline levels with concurrent tacrine use. Increased cholinergic side effects with other cholinergic agents, cholinesterase inhibitors, and succinylcholine. Antagonise effects of anticholinergic drugs. Increased risk of bradycardia with β-blockers and calcium channel blockers.
Food Interaction
Food reduces absorption.
Action
Description: Tacrine acts centrally and binds reversibly and inactivates cholinesterase, inhibiting hydrolysis of acetylcholine, prolonging their action in the brain.
Pharmacokinetics:
Absorption: Rapidly absorbed but large variations in oral bioavailability reported. Food reduces the absorption of tacrine by about 30-40%.
Distribution: Peak plasma concentrations achieved within 1-2 hr. About 55% bound to plasma proteins.
Metabolism: Undergoes extensive first-pass effect in the liver. Metabolised by the cytochrome P450 system (primarily CYP1A2) to various metabolites, with the main metabolte being 1-hydroxy metabolite velnacrine.
Excretion: Elimination half-life is 2-4 hr; little unchanged drug is excreted in the urine.
Storage
Store at 20-25°C.
Disclaimer: This information is independently developed by MIMS based on Tacrine 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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