The following additional adverse reactions have been identified during post-approval use of galantamine. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency:
Immune System Disorders
Nervous System Disorders
Ear and Labyrinth Disorders
Complete atrioventricular block
Hepatitis, Increased hepatic enzyme
Skin and Subcutaneous Tissue Disorders
Stevens-Johnson syndrome, Acute generalized exanthematous pustulosis, Erythema multiforme
Galantamine has the potential to interfere with the activity of anticholinergic medications [seeClinical Pharmacology (12.3)].
A synergistic effect is expected when cholinesterase inhibitors are given concurrently with succinylcholine, other cholinesterase inhibitors, similar neuromuscular blocking agents or cholinergic agonists such as bethanechol [see Clinical Pharmacology (12.3)].
There are no adequate data on the developmental risk associated with the use of galantamine tablets in pregnant women. In studies conducted in animals, administration of galantamine during pregnancy resulted in developmental toxicity (increased incidence of morphological abnormalities and decreased growth in offspring) at doses similar to or greater than those used clinically (see Data).
In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively. The background risk of major birth defects and miscarriage for the indicated population is unknown.
In rats, administration of galantamine (oral doses of 2, 8, or 16 mg/kg/day), from day 14 (females) or day 60 (males) prior to mating and continuing in females through the period of organogenesis, resulted in an increased incidence of fetal skeletal variations at the two highest doses, which were associated with maternal toxicity. The no-effect dose for embryo-fetal developmental toxicity in rats (2 mg/kg/day) is approximately equal to the maximum recommended human dose (MRHD) of 24 mg/day on a body surface area (mg/m2) basis. When galantamine (oral doses of 4, 12, 28, or 40 mg/kg/day) was administered to pregnant rabbits throughout the period of organogenesis, small increases in fetal visceral malformations and skeletal variations were observed at the highest dose. The no-effect dose for embryo-fetal developmental toxicity in rabbits (28 mg/kg/day) is approximately 20 times the MRHD on a mg/m2 basis. In a study in which pregnant rats were orally dosed with galantamine (2, 8, or 16 mg/kg/day) from the beginning of organogenesis through day 21 post-partum, pup weights were decreased at birth and during the lactation period at the two highest doses, which were associated with maternal toxicity. The no-effect dose for pre and postnatal developmental toxicity in rats (2 mg/kg/day) is approximately equal to the MRHD on a mg/m2 basis.
There are no data on the presence of galantamine in human milk, the effects on the breastfed infant, or the effects of galantamine tablets on milk production.
The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for galantamine tablets and any potential adverse effects on the breastfed infant from galantamine tablets or from the underlying maternal condition.
Eight double-blind, placebo-controlled clinical trials and 5 open-label trials in a total of 6519 patients have investigated galantamine in the treatment of mild to moderate dementia of the Alzheimer’s type [see Adverse Reactions (6.1) and Clinical Studies (14)]. The mean age of patients enrolled in these clinical studies was 75 years; 78% of these patients were between 65 and 84 years of age, and 10% of patients were 85 years of age or older.
In patients with moderate hepatic impairment, a dosage adjustment is recommended. The use of galantamine in patients with severe hepatic impairment is not recommended [see Dosage and Administration (2.3) and Clinical Pharmacology (12.3)].
In patients with a creatinine clearance of 9 to 59 mL/min, a dosage adjustment is recommended. The use of galantamine in patients with creatinine clearance less than 9 mL/min is not recommended [see Dosage and Administration (2.4) and Clinical Pharmacology (12.3)].
Because strategies for the management of overdose are continually evolving, it is advisable to contact a poison control center to determine the latest recommendations for the management of an overdose of any drug.
As in any case of overdose, general supportive measures should be utilized. Signs and symptoms of significant overdosing of galantamine are predicted to be similar to those of overdosing of other cholinomimetics. These effects generally involve the central nervous system, the parasympathetic nervous system, and the neuromuscular junction. In addition to muscle weakness or fasciculations, some or all of the following signs of cholinergic crisis may develop: severe nausea, vomiting, gastrointestinal cramping, salivation, lacrimation, urination, defecation, sweating, bradycardia, hypotension, respiratory depression, collapse and convulsions. Increasing muscle weakness is a possibility and may result in death if respiratory muscles are involved.
Tertiary anticholinergics such as atropine may be used as an antidote for galantamine hydrobromide overdosage. Intravenous atropine sulfate titrated to effect is recommended at an initial dose of 0.5 to 1 mg i.v. with subsequent doses based upon clinical response. Atypical responses in blood pressure and heart rate have been reported with other cholinomimetics when co-administered with quaternary anticholinergics. It is not known whether galantamine and/or its metabolites can be removed by dialysis (hemodialysis, peritoneal dialysis, or hemofiltration). Dose-related signs of toxicity in animals included hypoactivity, tremors, clonic convulsions, salivation, lacrimation, chromodacryorrhea, mucoid feces, and dyspnea.
In one postmarketing report, one patient who had been taking 4 mg of galantamine daily for a week inadvertently ingested eight 4 mg tablets (32 mg total) on a single day. Subsequently, she developed bradycardia, QT prolongation, ventricular tachycardia and torsades de pointes accompanied by a brief loss of consciousness for which she required hospital treatment. Two additional cases of accidental ingestion of 32 mg (nausea, vomiting, and dry mouth; nausea, vomiting, and substernal chest pain) and one of 40 mg (vomiting), resulted in brief hospitalizations for observation with full recovery. One patient, who was prescribed 24 mg/day and had a history of hallucinations over the previous two years, mistakenly received 24 mg twice daily for 34 days and developed hallucinations requiring hospitalization. Another patient, who was prescribed 16 mg/day of oral solution, inadvertently ingested 160 mg (40 mL) and experienced sweating, vomiting, bradycardia, and near-syncope one hour later, which necessitated hospital treatment. His symptoms resolved within 24 hours.
Galantamine tablets, USP are galantamine hydrobromide, a reversible, competitive acetylcholinesterase inhibitor. Galantamine hydrobromide is known chemically as (4aS , 6R , 8aS)-4a, 5, 9, 10, 11, 12-hexahydro-3-methoxy-11-methyl-6H -benzofuro[3a, 3, 2- ef ]benzazepin-6-ol hydrobromide. It has a molecular formula of C17 H21 NO3• HBr and a molecular weight of 368.27. Galantamine hydrobromide, USP is a white to almost white powder and is soluble in 0.1 N sodium hydroxide, sparingly soluble in water, very slightly soluble in alcohol and insoluble in n-propanol. The structural formula for galantamine hydrobromide is:
Galantamine Tablets USP, for oral use are available as round, biconvex, filmcoated immediate release tablets of 4 mg (light-pink), 8 mg (off-white), and 12 mg (off-white). Each 4, 8, and 12 mg (base equivalent) tablet contains 5.126, 10.252, and 15.378 mg of galantamine hydrobromide, respectively. Inactive ingredients include colloidal silicon dioxide, crospovidone, hypromellose, lactose monohydrate, magnesium stearate, propylene glycol and titanium dioxide. Additionally each 4 mg tablet contains iron oxide red and each 8 mg and 12 mg tablet contains iron oxide yellow.
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