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Galantamine Tablets, USP | Galantamine hydrobromide

05:27 EDT 27th August 2014 | BioPortfolio

Note: While we endeavour to keep our records up-to-date one should not rely on these details being accurate without first consulting a professional. Click here to read our full medical disclaimer.

Galantamine hydrobromide is 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][2]benzazepin-6-ol hydrobromide. It has molecular formula of CHNO•HBr and a molecular weight of 368.27. Galantamine hydrobromide, USP is a white to almost white powder and is sparingly soluble in water. The structural formula for galantamine hydrobromide is:

Each galantamine tablet intended for oral administration contains galantamine hydrobromide equivalent to galantamine 4 mg or 8 mg or 12 mg. In addition, each tablet contains the following inactive ingredients: colloidal silicon dioxide, crospovidone, hydroxypropyl methylcellulose, 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.

IMAGE galantamine-hydrobromide-figure-01.jpg

Although the etiology of cognitive impairment in Alzheimer’s disease (AD) is not fully understood, it has been reported that acetylcholine-producing neurons degenerate in the brains of patients with Alzheimer’s disease. The degree of this cholinergic loss has been correlated with degree of cognitive impairment and density of amyloid plaques (a neuropathological hallmark of Alzheimer’s disease).

Galantamine, a tertiary alkaloid, is a competitive and reversible inhibitor of acetylcholinesterase. While the precise mechanism of galantamine’s action is unknown, it is postulated to exert its therapeutic effect by enhancing cholinergic function. This is accomplished by increasing the concentration of acetylcholine through reversible inhibition of its hydrolysis by cholinesterase. If this mechanism is correct, galantamine’s effect may lessen as the disease process advances and fewer cholinergic neurons remain functionally intact. There is no evidence that galantamine alters the course of the underlying dementing process.

Galantamine is well absorbed with absolute oral bioavailability of about 90%. It has a terminal elimination half-life of about 7 hours and pharmacokinetics are linear over the range of 8 to 32 mg/day.

The maximum inhibition of acetylcholinesterase activity of about 40% was achieved about one hour after a single oral dose of 8 mg galantamine in healthy male subjects.

Galantamine is rapidly and completely absorbed with time to peak concentration about 1 hour. Bioavailability of the tablet was the same as the bioavailability of an oral solution. Food did not affect the AUC of galantamine but C decreased by 25% and T was delayed by 1.5 hours. The mean volume of distribution of galantamine is 175 L.

The plasma protein binding of galantamine is 18% at therapeutically relevant concentrations. In whole blood, galantamine is mainly distributed to blood cells (52.7%). The blood to plasma concentration ratio of galantamine is 1.2.

Galantamine is metabolized by hepatic cytochrome P450 enzymes, glucuronidated, and excreted unchanged in the urine. In vitro studies indicate that cytochrome CYP2D6 and CYP3A4 were the major cytochrome P450 isoenzymes involved in the metabolism of galantamine, and inhibitors of both pathways increase oral bioavailability of galantamine modestly (see PRECAUTIONS, Drug-Drug Interactions). O-demethylation, mediated by CYP2D6 was greater in extensive metabolizers of CYP2D6 than in poor metabolizers. In plasma from both poor and extensive metabolizers, however, unchanged galantamine and its glucuronide accounted for most of the sample radioactivity.

In studies of oral H-galantamine, unchanged galantamine and its glucuronide, accounted for most plasma radioactivity in poor and extensive CYP2D6 metabolizers. Up to 8 hours post-dose, unchanged galantamine accounted for 39 to 77% of the total radioactivity in the plasma, and galantamine glucuronide for 14 to 24%. By 7 days, 93 to 99% of the radioactivity had been recovered, with about 95% in urine and about 5% in the feces. Total urinary recovery of unchanged galantamine accounted for, on average, 32% of the dose and that of galantamine glucuronide for another 12% on average.

After i.v. or oral administration, about 20% of the dose was excreted as unchanged galantamine in the urine in 24 hours, representing a renal clearance of about 65 mL/min, about 20 to 25% of the total plasma clearance of about 300 mL/min.

Approximately 7% of the normal population has a genetic variation that leads to reduced levels of activity of CYP2D6 isozyme. Such individuals have been referred to as poor metabolizers. After a single oral dose of 4 mg or 8 mg galantamine, CYP2D6 poor metabolizers demonstrated a similar C and about 35% AUC∞ increase of unchanged galantamine compared to extensive metabolizers.

A total of 356 patients with Alzheimer’s disease enrolled in two Phase 3 studies were genotyped with respect to CYP2D6 (n=210 hetero-extensive metabolizers, 126 homo-extensive metabolizers, and 20 poor metabolizers). Population pharmacokinetic analysis indicated that there was a 25% decrease in median clearance in poor metabolizers compared to extensive metabolizers. Dosage adjustment is not necessary in patients identified as poor metabolizers as the dose of drug is individually titrated to tolerability.

Following a single 4 mg dose of galantamine tablets, the pharmacokinetics of galantamine in subjects with mild hepatic impairment (n=8; Child-Pugh score of 5 to 6) were similar to those in healthy subjects. In patients with moderate hepatic impairment (n=8; Child-Pugh score of 7 to 9), galantamine clearance was decreased by about 25% compared to normal volunteers. Exposure would be expected to increase further with increasing degree of hepatic impairment (see PRECAUTIONS and DOSAGE AND ADMINISTRATION).

Following a single 8 mg dose of galantamine tablets, AUC increased by 37% and 67% in moderate and severely renal-impaired patients compared to normal volunteers (see PRECAUTIONS and DOSAGE AND ADMINISTRATION).

Data from clinical trials in patients with Alzheimer’s disease indicate that galantamine concentrations are 30 to 40% higher than in healthy young subjects.

No specific pharmacokinetic study was conducted to investigate the effect of gender and race on the disposition of galantamine, but a population pharmacokinetic analysis indicates (n= 539 males and 550 females) that galantamine clearance is about 20% lower in females than in males (explained by lower body weight in females) and race (n= 1029 White, 24 Black, 13 Asian and 23 other) did not affect the clearance of galantamine.

(see also PRECAUTIONS, Drug-Drug Interactions).

Multiple metabolic pathways and renal excretion are involved in the elimination of galantamine so no single pathway appears predominant. Based on in vitro studies, CYP2D6 and CYP3A4 were the major enzymes involved in the metabolism of galantamine. CYP2D6 was involved in the formation of O-desmethyl-galantamine, whereas CYP3A4 mediated the formation of galantamine-N-oxide. Galantamine is also glucuronidated and excreted unchanged in urine.

(A) Effect of Other Drugs on the Metabolism of Galantamine:

Drugs that are potent inhibitors for CYP2D6 or CYP3A4 may increase the AUC of galantamine. Multiple dose pharmacokinetic studies demonstrated that the AUC of galantamine increased 30% and 40%, respectively, during co-administration of ketoconazole and paroxetine. As co-administered with erythromycin, another CYP3A4 inhibitor, the galantamine AUC increased only 10%. Population PK analysis with a database of 852 patients with Alzheimer’s disease showed that the clearance of galantamine was decreased about 25 to 33% by concurrent administration of amitriptyline (n = 17), fluoxetine (n = 48), fluvoxamine (n = 14), and quinidine (n = 7), known inhibitors of CYP2D6.

Concurrent administration of H-antagonists demonstrated that ranitidine did not affect the pharmacokinetics of galantamine, and cimetidine increased the galantamine AUC by approximately 16%. A multiple dose pharmacokinetic study with concurrent administration of memantine, an N-methyl-D-aspartate (NMDA) receptor antagonist, demonstrated that co-administration of memantine in a dose of 10 mg BID did not affect the pharmacokinetic profile of galantamine (16 mg daily) at steady state.

(B) Effect of Galantamine on the Metabolism of Other Drugs:

In vitro studies show that galantamine did not inhibit the metabolic pathways catalyzed by CYP1A2, CYP2A6, CYP3A4, CYP4A, CYP2C, CYP2D6 and CYP2E1. This indicated that the inhibitory potential of galantamine towards the major forms of cytochrome P450 is very low. Multiple doses of galantamine (24 mg/day) had no effect on the pharmacokinetics of digoxin and warfarin (R- and S- forms). Galantamine had no effect on the increased prothrombin time induced by warfarin.

The effectiveness of galantamine hydrobromide as a treatment for Alzheimer’s disease is demonstrated by the results of 5 randomized, double-blind, placebo-controlled clinical investigations in patients with probable Alzheimer’s disease, 4 with the tablet [diagnosed by NINCDS-ADRDA criteria, with Mini-Mental State Examination scores that were ≥ 10 and ≤ 24]. Doses studied with the tablets were 8 to 32 mg/day given as twice daily doses. In 3 of the 4 studies, patients were started on a low dose of 8 mg, then titrated weekly by 8 mg/day to 24 or 32 mg as assigned. In the fourth study (USA 4-week Dose-Escalation Fixed-Dose Study) dose escalation of 8 mg/day occurred over 4 week intervals. The mean age of patients participating in these 4 galantamine trials was 75 years with a range of 41 to 100. Approximately 62% of patients were women and 38% were men. The racial distribution was White 94%, Black 3% and other races 3%. Two other studies examined a three times daily dosing regimen; these also showed or suggested benefit but did not suggest an advantage over twice daily dosing.

In each study, the primary effectiveness of galantamine was evaluated using a dual outcome assessment strategy as measured by the Alzheimer’s Disease Assessment Scale (ADAS-cog) and the Clinician’s Interview Based Impression of Change that required the use of caregiver information (CIBIC-plus).

The ability of galantamine to improve cognitive performance was assessed with the cognitive sub-scale of the Alzheimer’s Disease Assessment Scale (ADAS-cog), a multi-item instrument that has been extensively validated in longitudinal cohorts of Alzheimer’s disease patients. The ADAS-cog examines selected aspects of cognitive performance including elements of memory, orientation, attention, reasoning, language and praxis. The ADAS-cog scoring range is from 0 to 70, with higher scores indicating greater cognitive impairment. Elderly normal adults may score as low as 0 or 1, but it is not unusual for non-demented adults to score slightly higher.

The patients recruited as participants in each study had mean scores on ADAS-cog of approximately 27 units, with a range from 5 to 69. Experience gained in longitudinal studies of ambulatory patients with mild to moderate Alzheimer’s disease suggests that they gain 6 to 12 units a year on the ADAS-cog. Lesser degrees of change, however, are seen in patients with very mild or very advanced disease because the ADAS-cog is not uniformly sensitive to change over the course of the disease. The annualized rate of decline in the placebo patients participating in galantamine trials was approximately 4.5 units per year.

The ability of galantamine tablets to produce an overall clinical effect was assessed using a Clinician’s Interview Based Impression of Change that required the use of caregiver information, the CIBIC-plus. The CIBIC-plus is not a single instrument and is not a standardized instrument like the ADAS-cog. Clinical trials for investigational drugs have used a variety of CIBIC formats, each different in terms of depth and structure. As such, results from a CIBIC-plus reflect clinical experience from the trial or trials in which it was used and cannot be compared directly with the results of CIBIC-plus evaluations from other clinical trials. The CIBIC-plus used in the trials was a semi-structured instrument based on a comprehensive evaluation at baseline and subsequent time-points of 4 major areas of patient function: general, cognitive, behavioral and activities of daily living. It represents the assessment of a skilled clinician based on his/her observation at an interview with the patient, in combination with information supplied by a caregiver familiar with the behavior of the patient over the interval rated. The CIBIC-plus is scored as a seven point categorical rating, ranging from a score of 1, indicating "markedly improved," to a score of 4, indicating "no change" to a score of 7, indicating "marked worsening." The CIBIC-plus has not been systematically compared directly to assessments not using information from caregivers (CIBIC) or other global methods.

In a study of 21 weeks duration, 978 patients were randomized to doses of 8, 16, or 24 mg of galantamine per day, or to placebo, each given in 2 divided doses. Treatment was initiated at 8 mg/day for all patients randomized to galantamine and increased by 8 mg/day every 4 weeks. Therefore, the maximum titration phase was 8 weeks and the minimum maintenance phase was 13 weeks (in patients randomized to 24 mg/day of galantamine).

Figure 1 illustrates the time course for the change from baseline in ADAS-cog scores for all four dose groups over the 21 weeks of the study. At 21 weeks of treatment, the mean differences in the ADAS-cog change scores for the galantamine -treated patients compared to the patients on placebo were 1.7, 3.3, and 3.6 units for the 8, 16 and 24 mg/day treatments, respectively. The 16 mg/day and 24 mg/day treatments were statistically significantly superior to placebo and to the 8 mg/day treatment. There was no statistically significant difference between the 16 mg/day and 24 mg/day dose groups.

Figure 1

Time-Course of the Change from Baseline in ADAS-cog Score for Patients completing 21 Weeks (5 Months) of Treatment

Figure 2 illustrates the cumulative percentages of patients from each of the four treatment groups who had attained at least the measure of improvement in ADAS-cog score shown on the X-axis. Three change scores (10-point, 7-point and 4-point reductions) and no change in score from baseline have been identified for illustrative purposes, and the percent of patients in each group achieving that result is shown in the inset table.

The curves demonstrate that both patients assigned to galantamine and placebo have a wide range of responses, but that the galantamine groups are more likely to show the greater improvements.

Figure 2

Cumulative Percentage of Patients completing 21 Weeks of Double-Blind Treatment with Specified Changes from Baseline in ADAS-cog Scores. The Percentages of Randomized Patients Who Completed the Study Were: Placebo 84%, 8 mg/day 77%, 16 mg/day 78% and 24 mg/day 78%.

IMAGE galantamine-hydrobromide-figure-02.jpgIMAGE galantamine-hydrobromide-figure-03.jpg
Treatment
Change  in  ADAS - cog

- 10 
- 7 
- 4 

Placebo
3.6%
7.6%
19.6%
41.8%
8 mg/day
5.9%
13.9%
25.7%
46.5%
16 mg/day
7.2%
15.9%
35.6%
65.4%
24 mg/day
10.4%
22.3%
37.0%
64.9%

Figure 3 is a histogram of the percentage distribution of CIBIC-plus scores attained by patients assigned to each of the four treatment groups who completed 21 weeks of treatment. The galantamine -placebo differences for these groups of patients in mean rating were 0.15, 0.41 and 0.44 units for the 8, 16 and 24 mg/day treatments, respectively. The 16 mg/day and 24 mg/day treatments were statistically significantly superior to placebo. The differences vs. the 8 mg/day treatment for the 16 and 24 mg/day treatments were 0.26 and 0.29, respectively. There were no statistically significant differences between the 16 mg/day and 24 mg/day dose groups.

Figure 3

Distribution of CIBIC-plus Ratings at Week 21

IMAGE galantamine-hydrobromide-figure-04.jpg

In a study of 26 weeks duration, 636 patients were randomized to either a dose of 24 mg or 32 mg of galantamine hydrobromide per day, or to placebo, each given in two divided doses. The 26-week study was divided into a 3-week dose titration phase and a 23-week maintenance phase.

Figure 4 illustrates the time course for the change from baseline in ADAS-cog scores for all three dose groups over the 26 weeks of the study. At 26 weeks of treatment, the mean differences in the ADAS-cog change scores for the galantamine -treated patients compared to the patients on placebo were 3.9 and 3.8 units for the 24 mg/day and 32 mg/day treatments, respectively. Both treatments were statistically significantly superior to placebo, but were not significantly different from each other.

Figure 4

Time-Course of the Change from Baseline in ADAS-cog Score for Patients completing 26 Weeks of Treatment

Figure 5 illustrates the cumulative percentages of patients from each of the three treatment groups who had attained at least the measure of improvement in ADAS-cog score shown on the X-axis. Three change scores (10-point, 7-point and 4-point reductions) and no change in score from baseline have been identified for illustrative purposes, and the percent of patients in each group achieving that result is shown in the inset table.

The curves demonstrate that both patients assigned to galantamine and placebo have a wide range of responses, but that the galantamine groups are more likely to show the greater improvements. A curve for an effective treatment would be shifted to the left of the curve for placebo, while an ineffective or deleterious treatment would be superimposed upon, or shifted to the right of the curve for placebo, respectively.

Figure 5

Cumulative Percentage of Patients completing 26 Weeks of Double-Blind Treatment with Specified Changes from Baseline in ADAS-cog Scores. The Percentages of Randomized Patients Who Completed the Study Were: Placebo 81%, 24 mg/day 68%, and 32 mg/day 58%.

IMAGE galantamine-hydrobromide-figure-05.jpgIMAGE galantamine-hydrobromide-figure-06.jpg
Treatment
Change  in  ADAS - cog

- 10
- 7
- 4

Placebo
2.1%
5.7%
16.6%
43.9%
24 mg/day
7.6%
18.3%
33.6%
64.1%
32 mg/day
11.1%
19.7%
33.3%
58.1%

Figure 6 is a histogram of the percentage distribution of CIBIC-plus scores attained by patients assigned to each of the three treatment groups who completed 26 weeks of treatment. The mean galantamine -placebo differences for these groups of patients in the mean rating were 0.28 and 0.29 units for 24 and 32 mg/day of galantamine, respectively. The mean ratings for both groups were statistically significantly superior to placebo, but were not significantly different from each other.

Figure 6

Distribution of CIBIC-plus Ratings at Week 26

IMAGE galantamine-hydrobromide-figure-07.jpg

In a study of 26 weeks duration identical in design to the USA 26-Week Fixed-Dose Study, 653 patients were randomized to either a dose of 24 mg or 32 mg of galantamine hydrobromide per day, or to placebo, each given in two divided doses. The 26-week study was divided into a 3-week dose titration phase and a 23-week maintenance phase.

Figure 7 illustrates the time course for the change from baseline in ADAS-cog scores for all three dose groups over the 26 weeks of the study. At 26 weeks of treatment, the mean differences in the ADAS-cog change scores for the galantamine-treated patients compared to the patients on placebo were 3.1 and 4.1 units for the 24 mg/day and 32 mg/day treatments, respectively. Both treatments were statistically significantly superior to placebo, but were not significantly different from each other.

Figure 7

Time-Course of the Change from Baseline in ADAS-cog Score for Patients completing 26 Weeks of Treatment

Figure 8 illustrates the cumulative percentages of patients from each of the three treatment groups who had attained at least the measure of improvement in ADAS-cog score shown on the X-axis. Three change scores (10-point, 7-point and 4-point reductions) and no change in score from baseline have been identified for illustrative purposes, and the percent of patients in each group achieving that result is shown in the inset table.

The curves demonstrate that both patients assigned to galantamine and placebo have a wide range of responses, but that the galantamine groups are more likely to show the greater improvements.

Figure 8

Cumulative Percentage of Patients completing 26 Weeks of Double-Blind Treatment with Specified Changes from Baseline in ADAS-cog Scores. The Percentages of Randomized Patients Who Completed the Study Were: Placebo 87%, 24 mg/day 80%, and 32 mg/day 75%.

IMAGE galantamine-hydrobromide-figure-08.jpgIMAGE galantamine-hydrobromide-figure-09.jpg
Treatment
Change  in  ADAS - cog

- 10 
- 7 
- 4 

Placebo
1.2%
5.8%
15.2%
39.8%
24 mg/day
4.5%
15.4%
30.8%
65.4%
32 mg/day
7.9%
19.7%
34.9%
63.8%

Figure 9 is a histogram of the percentage distribution of CIBIC-plus scores attained by patients assigned to each of the three treatment groups who completed 26 weeks of treatment. The mean galantamine-placebo differences for these groups of patients in the mean rating of change from baseline were 0.34 and 0.47 for 24 and 32 mg/day of galantamine, respectively. The mean ratings for the galantamine groups were statistically significantly superior to placebo, but were not significantly different from each other.

Figure 9

Distribution of CIBIC-plus Rating at Week 26

IMAGE galantamine-hydrobromide-figure-10.jpg

In a study of 13 weeks duration, 386 patients were randomized to either a flexible dose of 24 to 32 mg/day of galantamine or to placebo, each given in two divided doses. The 13-week study was divided into a 3-week dose titration phase and a 10-week maintenance phase. The patients in the active treatment arm of the study were maintained at either 24 mg/day or 32 mg/day at the discretion of the investigator.

Figure 10 illustrates the time course for the change from baseline in ADAS-cog scores for both dose groups over the 13 weeks of the study. At 13 weeks of treatment, the mean difference in the ADAS-cog change scores for the treated patients compared to the patients on placebo was 1.9. Galantamine at a dose of 24 to 32 mg/day were statistically significantly superior to placebo.

Figure 10

Time-Course of the Change from Baseline in ADAS-cog Score for Patients completing 13 Weeks of Treatment

Figure 11 illustrates the cumulative percentages of patients from each of the two treatment groups who had attained at least the measure of improvement in ADAS-cog score shown on the X-axis. Three change scores (10-point, 7-point and 4-point reductions) and no change in score from baseline have been identified for illustrative purposes, and the percent of patients in each group achieving that result is shown in the inset table.

The curves demonstrate that both patients assigned to galantamine and placebo have a wide range of responses, but that the galantamine group is more likely to show the greater improvement.

Figure 11

Cumulative Percentage of Patients completing 13 Weeks of Double-Blind Treatment with Specified Changes from Baseline in ADAS-cog Scores. The Percentages of Randomized Patients Who Completed the Study Were: Placebo 90%, 24-32 mg/day 67%.

IMAGE galantamine-hydrobromide-figure-11.jpgIMAGE galantamine-hydrobromide-figure-12.jpg
Treatment 
Change  in  ADAS - cog

- 10
- 7
- 4

Placebo 
1.9%
5.6%
19.4%
50.0%
24 or 32 mg/day 
7.1%
18.8%
32.9%
65.3%

Figure 12 is a histogram of the percentage distribution of CIBIC-plus scores attained by patients assigned to each of the two treatment groups who completed 13 weeks of treatment. The mean galantamine-placebo differences for the group of patients in the mean rating of change from baseline was 0.37 units. The mean rating for the 24 to 32 mg/day group was statistically significantly superior to placebo.

Figure 12

Distribution of CIBIC-plus Ratings at Week 13

IMAGE galantamine-hydrobromide-figure-13.jpg

Patient’s age, gender, or race did not predict clinical outcome of treatment.

Galantamine tablets are indicated for the treatment of mild to moderate dementia of the Alzheimer’s type.

Galantamine tablets are contraindicated in patients with known hypersensitivity to galantamine or to any excipients used in the formulation.

Galantamine, as a cholinesterase inhibitor, is likely to exaggerate the neuromuscular blocking effects of succinylcholine-type and similar neuromuscular blocking agents during anesthesia.

Because of their pharmacological action, cholinesterase inhibitors have vagotonic effects on the sinoatrial and atrioventricular nodes, leading to bradycardia and AV block. These actions may be particularly important to patients with supraventricular cardiac conduction disorders or to patients taking other drugs concomitantly that significantly slow heart rate. Postmarketing surveillance of marketed anticholinesterase inhibitors has shown, however, that bradycardia and all types of heart block have been reported in patients both with and without known underlying cardiac conduction abnormalities. Therefore all patients should be considered at risk for adverse effects on cardiac conduction.

In randomized controlled trials, bradycardia was reported more frequently in galantamine-treated patients than in placebo-treated patients, but was rarely severe and rarely led to treatment discontinuation. The overall frequency of this event was 2 to 3 % for galantamine doses up to 24 mg/day compared with <1% for placebo. No increased incidence of heart block was observed at the recommended doses.

Patients treated with galantamine up to 24 mg/day using the recommended dosing schedule showed a dose-related increase in risk of syncope (placebo 0.7% [2/286]; 4 mg BID 0.4% [3/692]; 8 mg BID 1.3% [7/552]; 12 mg BID 2.2% [6/273]).

Through their primary action, cholinomimetics may be expected to increase gastric acid secretion due to increased cholinergic activity. Therefore, patients should be monitored closely for symptoms of active or occult gastrointestinal bleeding, especially those with an increased risk for developing ulcers, e.g., those with a history of ulcer disease or patients using concurrent nonsteroidal anti-inflammatory drugs (NSAIDS). Clinical studies of galantamine hydrobromide have shown no increase, relative to placebo, in the incidence of either peptic ulcer disease or gastrointestinal bleeding.

Galantamine, as a predictable consequence of its pharmacological properties, has been shown to produce nausea, vomiting, diarrhea, anorexia, and weight loss (see ADVERSE REACTIONS).

Although this was not observed in clinical trials with galantamine, cholinomimetics may cause bladder outflow obstruction.

Cholinesterase inhibitors are believed to have some potential to cause generalized convulsions. However, seizure activity may also be a manifestation of Alzheimer’s disease. In clinical trials, there was no increase in the incidence of convulsions with galantamine, compared to placebo.

Because of its cholinomimetic action, galantamine should be prescribed with care to patients with a history of severe asthma or obstructive pulmonary disease.

Caregivers should be instructed about the recommended dosage and administration of galantamine hydrobromide. Galantamine tablets should be administered twice per day, preferably with the morning and evening meals. Dose escalation (dose increases) should follow a minimum of four weeks at prior dose.

Patients and caregivers should be advised that the most frequent adverse events associated with use of the drug can be minimized by following the recommended dosage and administration.

Patients and caregivers should be advised to ensure adequate fluid intake during treatment. If therapy has been interrupted for several days or longer, the patient should be restarted at the lowest dose and the dose escalated to the current dose.

In two randomized placebo controlled trials of 2 years duration in subjects with mild cognitive impairment (MCI), a total of 13 subjects on galantamine (n=1026) and 1 subject on placebo (n=1022) died. The deaths were due to various causes which could be expected in an elderly population; about half of the galantamine deaths appeared to result from various vascular causes (myocardial infarction, stroke, and sudden death).

Although the difference in mortality between galantamine and placebo-treated groups in these two studies was significant, the results are highly discrepant with other studies of galantamine. Specifically, in these two MCI studies, the mortality rate in the placebo-treated subjects was markedly lower than the rate in placebo-treated patients in trials of galantamine in Alzheimer’s disease or other dementias (0.7 per 1000 person years compared to 22 to 61 per 1000 person years, respectively). Although the mortality rate in the galantamine-treated MCI subjects was also lower than that observed in galantamine-treated patients in Alzheimer’s disease and other dementia trials (10.2 per 1000 person years compared to 23 to 31 per 1000 person years, respectively), the relative difference was much less. When the Alzheimer’s disease and other dementia studies were pooled (n=6000), the mortality rate in the placebo group numerically exceeded that in the galantamine group. Furthermore, in the MCI studies, no subjects in the placebo group died after 6 months, a highly unexpected finding in this population.

Individuals with mild cognitive impairment demonstrate isolated memory impairment greater than expected for their age and education, but do not meet current diagnostic criteria for Alzheimer’s disease.

In patients with moderately impaired hepatic function, dose titration should proceed cautiously (see CLINICAL PHARMACOLOGY and DOSAGE AND ADMINISTRATION). The use of galantamine in patients with severe hepatic impairment is not recommended.

In patients with moderately impaired renal function, dose titration should proceed cautiously (see CLINICAL PHARMACOLOGY and DOSAGE AND ADMINISTRATION). In patients with severely impaired renal function (CL< 9 mL/min) the use of galantamine are not recommended.

(see also CLINICAL PHARMACOLOGY, Drug-Drug Interactions).

Galantamine has the potential to interfere with the activity of anticholinergic medications.

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.

A) Effect of Other Drugs on Galantamine:

In vitro:

CYP3A4 and CYP2D6 are the major enzymes involved in the metabolism of galantamine. CYP3A4 mediates the formation of galantamine-N-oxide; CYP2D6 leads to the formation of O-desmethyl-galantamine. Because galantamine is also glucuronidated and excreted unchanged, no single pathway appears predominant.

In vivo:

Cimetidine and Ranitidine:

Galantamine was administered as a single dose of 4 mg on day 2 of a 3-day treatment with either cimetidine (800 mg daily) or ranitidine (300 mg daily). Cimetidine increased the bioavailability of galantamine by approximately 16%. Ranitidine had no effect on the PK of galantamine.

Ketoconazole:

Ketoconazole, a strong inhibitor of CYP3A4 and an inhibitor of CYP2D6, at a dose of 200 mg BID for 4 days, increased the AUC of galantamine by 30%.

Erythromycin:

Erythromycin, a moderate inhibitor of CYP3A4 at a dose of 500 mg QID for 4 days, affected the AUC of galantamine minimally (10% increase).

Paroxetine:

Paroxetine, a strong inhibitor of CYP2D6, at 20 mg/day for 16 days, increased the oral bioavailability of galantamine by about 40%.

Memantine:

Memantine, an N-methyl-D-aspartate receptor antagonist, at a dose of 10 mg BID, had no effect on the pharmacokinetics of galantamine (16 mg/day) at steady state.

B) Effect of Galantamine on Other Drugs:

In vitro:

Galantamine did not inhibit the metabolic pathways catalyzed by CYP1A2, CYP2A6, CYP3A4, CYP4A, CYP2C, CYP2D6 or CYP2E1. This indicates that the inhibitory potential of galantamine towards the major forms of cytochrome P450 is very low.

In vivo:

Warfarin:

Galantamine at 24 mg/day had no effect on the pharmacokinetics of R- and S-warfarin (25 mg single dose) or on the prothrombin time. The protein binding of warfarin was unaffected by galantamine.

Digoxin:

Galantamine at 24 mg/day had no effect on the steady-state pharmacokinetics of digoxin (0.375 mg once daily) when they were co-administered. In this study, however, one healthy subject was hospitalized for 2 and 3 degree heart block and bradycardia.

In a 24-month oral carcinogenicity study in rats, a slight increase in endometrial adenocarcinomas was observed at 10 mg/kg/day (4 times the Maximum Recommended Human Dose [MRHD] on a mg/m basis or 6 times on an exposure [AUC] basis) and 30 mg/kg/day (12 times MRHD on a mg/m basis or 19 times on an AUC basis). No increase in neoplastic changes was observed in females at 2.5 mg/kg/day (equivalent to the MRHD on a mg/mbasis or 2 times on an AUC basis) or in males up to the highest dose tested of 30 mg/kg/day (12 times the MRHD on a mg/m and AUC basis).

Galantamine was not carcinogenic in a 6-month oral carcinogenicity study in transgenic (P 53-deficient) mice up to 20 mg/kg/day, or in a 24-month oral carcinogenicity study in male and female mice up to 10 mg/kg/day (2 times the MRHD on a mg/m basis and equivalent on an AUC basis).

Galantamine produced no evidence of genotoxic potential when evaluated in the in vitro Ames S. typhimurium or E. coli reverse mutation assay, in vitro mouse lymphoma assay, in vivo micronucleus test in mice, or in vitro chromosome aberration assay in Chinese hamster ovary cells.

No impairment of fertility was seen in rats given up to 16 mg/kg/day (7 times the MRHD on a mg/mbasis) for 14 days prior to mating in females and for 60 days prior to mating in males.

Pregnancy Category B:

In a study in which rats were dosed from day 14 (females) or day 60 (males) prior to mating through the period of organogenesis, a slightly increased incidence of skeletal variations was observed at doses of 8 mg/kg/day (3 times the Maximum Recommended Human Dose [MRHD] on a mg/mbasis) and 16 mg/kg/day. In a study in which pregnant rats were dosed from the beginning of organogenesis through day 21 post-partum, pup weights were decreased at 8 and 16 mg/kg/day, but no adverse effects on other postnatal developmental parameters were seen. The doses causing the above effects in rats produced slight maternal toxicity. No major malformations were caused in rats given up to 16 mg/kg/day. No drug related teratogenic effects were observed in rabbits given up to 40 mg/kg/day (32 times the MRHD on a mg/m basis) during the period of organogenesis.

There are no adequate and well-controlled studies of galantamine in pregnant women. Galantamine should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

It is not known whether galantamine is excreted in human breast milk. Galantamine has no indication for use in nursing mothers.

There are no adequate and well-controlled trials documenting the safety and efficacy of galantamine in any illness occurring in children. Therefore, use of galantamine in children is not recommended.

In two large scale, placebo-controlled trials of 6 months duration in which patients were titrated weekly from 8 to 16 to 24, and to 32 mg/day, the risk of discontinuation because of an adverse event in the galantamine group exceeded that in the placebo group by about threefold. In contrast, in a 5-month trial with escalation of the dose by 8 mg/day every 4 weeks, the overall risk of discontinuation because of an adverse event was 7%, 7%, and 10% for the placebo, galantamine 16 mg/day, and galantamine 24 mg/day groups, respectively, with gastrointestinal adverse effects the principle reason for discontinuing galantamine. Table 1 shows the most frequent adverse events leading to discontinuation in this study.

Table 1 Most Frequent Adverse Events Leading to Discontinuation in a Placebo-Controlled, Double-Blind Trial with a 4-Week Dose Escalation Schedule
4 - Week  Escalation
Adverse  Event
Placebo
16  mg / day
24  mg / day

N = 286 
N = 279 

Manufacturer

Zydus Pharmaceuticals (USA) Inc.

Active Ingredients

Source

Drugs and Medications [178 Associated Drugs and Medications listed on BioPortfolio]

Galantamine [Aurobindo Pharma Limited]

Galantamine Tablets, USP

Galantamine [Greenstone LLC]

Galantamine hydrobromide [Sun Pharma Global FZE]

Galantamine Hydrobromide Extended-Release Capsules

Galantamine hydrobromide [Global Pharmaceuticals, Division of Impax Laboratories Inc.]

GALANTAMINE HYDROBROMIDEEXTENDED-RELEASE CAPSULES

Galantamine hydrobromide [Watson Laboratories, Inc.]

Galantamine Hydrobromide Extended-release Capsules

Clinical Trials [78 Associated Clinical Trials listed on BioPortfolio]

A Study of the Safety and Effectiveness of Galantamine Hydrobromide in Patients With Alzheimer's Disease

The purpose of this study is to evaluate the safety and effectiveness of galantamine hydrobromide in patients with Alzheimer's disease who have not received or have not responded to treatm...

A Study of the Effectiveness and Safety of Galantamine Hydrobromide on Cognitive Impairment in Patients With Schizophrenia.

The purpose of this study is to determine if adding extended-release galantamine hydrobromide, compared with adding placebo, to current atypical antipsychotic therapy is well tolerated and...

A Study of the Safety and Effectiveness of Galantamine in Patients With Alzheimer's Disease

The purpose of this study is to evaluate the long-term efficacy and safety of galantamine in patients with Alzheimer's disease.

The Efficacy of Galantamine on the Attention and the Frontal Function of the Patients With Dementia of Alzheimer Type

The purpose of this study is to assess the efficacy of galantamine on the attention of patients with Alzheimer's Disease, how an improvement of attention of Alzheimer's Disease patients a...

Safety and Efficacy of High Dose, Rapid Titration Galantamine in Patients With Alzheimer's Disease

The purpose of this study was to determine the safety and effectiveness of a relatively high dose of galantamine, 32 mg /day in a three-times daily dosage, compared with placebo in treati...

PubMed Articles [17 Associated PubMed Articles listed on BioPortfolio]

Galantamine is not a positive allosteric modulator of human α4β2 or α7 nicotinic acetylcholine receptors.

The alkaloid galantamine was originally isolated from the green snowdrop Galanthus woronowii and is currently marketed as a drug for treatment of mild to moderate dementia in Alzheimer's disease patie...

Exploring the effects of galantamine paired with meditation and dream reliving on recalled dreams: Toward an integrated protocol for lucid dream induction and nightmare resolution.

An experimental home study examined the impact of a pre-sleep protocol for enhancing self-awareness, lucidity, and responsiveness in dreams. It included ingesting the cholinesterase inhibitor galantam...

Acceleration of NLRP3 inflammasome by chronic cerebral hypoperfusion in Alzheimer's disease model mouse.

Cerebral neuroinflammation defines a novel pathway for progressing Alzheimer's disease (AD) pathology. We investigated immunohistological changes of neuroinflammation with nucleotide-binding domain an...

Galantamine-Memantine Combination for Cognitive Impairments Due to Electroconvulsive Therapy, Traumatic Brain Injury, and Neurologic and Psychiatric Disorders: Kynurenic Acid and Mismatch Negativity Target Engagement.

Cognitive impairments due to electroconvulsive therapy (ECT), traumatic brain injury (TBI), and neurologic and psychiatric disorders are prevalent. Cholinergic and glutamatergic pathways, α-7 nicotin...

Pre-sleep treatment with galantamine stimulates lucid dreaming: A double-blind, placebo-controlled, crossover study.

Lucid dreaming is a remarkable state of consciousness in which one is aware of the fact that one is dreaming while continuing to dream. Based on the strong relationship between physiological activatio...

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