Galantamine is indicated for the treatment of mild to moderate dementia of the Alzheimer’s type.
Drugs for Dementia
Galantamine is a cholinomimetic agent. It is a competitive and reversible inhibitor of the enzyme acetylcholinesterase. In addition, Galantamine enhances the intrinsic action of acetylcholine on nicotinic receptors. As a result, an increased activity in the cholinergic system associated with improved cognitive function can be achieved in patients with dementia of the Alzheimer’s type.
Galantamine is a phenanthrene alkaloid and a reversible, competitive acetylcholinesterase inhibitor. It is not structurally related to other acetylcholinesterase inhibitors. Galantamine’s proposed mechanism of action involves the reversible inhibition of acetylcholinesterase, which prevents the hydrolysis of acetycholine, leading to an increased concentration of acetylcholine at cholinergic synapses. Galantamine also binds allosterically with nicotinic acetylcholine receptors and may possibly potentiate the action of agonists (such as acetylcholine) at these receptors.
Adults: The recommended starting dose of Galantamine is 4 mg twice daily (8 mg/day). The dose should be increased to the initial maintenance dose of 8 mg twice daily (16 mg/day) after a minimum of 4 weeks. A further increase to 12 mg twice daily (24 mg/day) should be attempted after a minimum of 4 weeks at 8 mg twice daily (16 mg/day).
Galantamine tablets should be administered twice daily, preferably with morning and evening meals.
ay antagonise the effect of other cholinomimetics (e.g. donepezil, neostigmine, systemic pilocarpine). Pharmacodynamic interaction w/ drugs that significantly reduce the heart (e.g. digoxin, β-blockers, certain Ca-channel blocking agents and amiodarone). May exaggerate succinylcholine-type muscle relaxation during anaesth, esp in pseudocholinesterase deficiency.
Galantamine is contraindicated in patients with renal impairment; breast feeding and known hypersensitivity to the active substance or to any of the excipients
Common side effects are nausea, vomiting, diarrhoea, abdominal pain, dyspepsia; syncope; rhinitis; sleep disturbances, dizziness, confusion, depression, headache, fatigue, anorexia, tremor; fever; weight loss; less commonly arrhythmias, palpitation, myocardial infarction, cerebrovascular disease, paraesthesia, tinnitus, and leg cramps.
Pregnancy category B. Galantamine should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. It should not be used during breast-feeding. However, if its use is unavoidable, then breast-feeding should be discontinued.
Caution should be taken in patients with cardiac disease; electrolyte disturbances; susceptibility to peptic ulcers; asthma, chronic obstructive pulmonary disease, pulmonary infection. Galantamine should be avoided in urinary retention and gastro-intestinal obstruction.
Muscle weakness or fasciculations, severe nausea, vomiting GI cramping, salivation, lacrimation, urination, defecation, sweating, bradycardia, hypotension, collapse and convulsions.
Management: General supportive measures. Anticholinergics such as atropine (with initial dose of 0.5-1 mg IV) may be used as general antidote.
Galantamine is not recommended in children.
Hepatic impaired patients: In patients with moderately impaired hepatic function, the total daily dose should generally not exceed 16 mg/day. The use of Galantamine in patients with severe hepatic impairment is not recommended.
Renal impaired patients: For patients with moderate renal impairment the dose should generally not exceed 16 mg/day. In patients with severe renal impairment (creatinine clearance <9 mL/min), the use of Galantamine is not recommended.
Store in a cool and dry place. Protect from light.