Reminyl

Paroxetine, a strong inhibitor of CYP2D6, increased the AUC of 4 mg b.i.d., 8 mg b.i.d. and 12 mg b.i.d. galantamine by 40%, 45% and 48 %, respectively, in 16 healthy volunteers (8 males and 8 females) who received galantamine together with 20 mg/day paroxetine.

A synergistic effect may be expected when cholinesterase inhibitors are given concurrently with succinylcholine, similar neuromuscular blocking agents or cholinergic agonists such as bethanechol.

Galantamine at 12 mg b.i.d. had no effect on the pharmacokinetics of R- and S- warfarin (25 mg single dose) or on the prothrombin time (n=16 males). The protein binding of warfarin was unaffected by galantamine.

Few patients in the clinical trials received neuroleptics, antidepressants or anticonvulsants, there is thus limited information concerning the interaction of REMINYL and REMINYL ER with these drugs.

Galantamine at 12 mg b.i.d. 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^nd and 3^rd degree heart block and bradycardia (n=8 males and 8 females).

Erythromycin, a moderate inhibitor of CYP3A4 at a dose of 500 mg q.i.d. for 4 days increased the AUC of galantamine by 10% when subjects received galantamine 4 mg b.i.d. for 6 days (n=8 males and 8 females).

Because of their mechanism of action, cholinesterase inhibitors have the potential to interfere with the activity of anticholinergic medications.

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 was administered as a single dose of 4 mg on Day 2 of a 3-day treatment with either cimetidine (800 mg daily; n=6 males and 6 females) or ranitidine (300 mg daily; n=6 males and 6 females). Cimetidine increased the bioavailability of galantamine by approximately 16%. Ranitidine had no effect on the pharmacokinetics of galantamine.

Interactions with food have not been established.

Interactions with laboratory tests have not been established.

In a multiple dose pharmacokinetic study in healthy volunteers (n=15, age range 21-55 years), concurrent administration of memantine at a dose of 10 mg b.i.d. did not affect the pharmacokinetic profile of galantamine (16 mg daily) at steady state.

The safety of co-administering memantine and galantamine in patients with Alzheimer's disease has not been studied in clinical trials.

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.

Interactions with herbal products have not been established.

Ketoconazole, a strong inhibitor of CYP3A4 and an inhibitor of CYP2D6, at a dose of 200 mg b.i.d. for 4 days, increased the AUC of galantamine by 30% when subjects were treated with galantamine 4 mg b.i.d. for 8 days (n=8 males and 8 females).

Single in vitro applications of galantamine dose-dependently modulate the effect on nicotinic receptors, having a positive allosteric (sensitizing) effect at concentrations below 0.28 μg/mL (1 μM) and an inhibitory effect at higher concentrations. Chronic in vitro or in vivo studies on nicotinic receptor modulation have not been conducted.

It is unknown whether galantamine has an effect on the pharmacodynamic action of other drugs that act on cholinergic nicotinic receptors (see Action and Clinical Pharmacology).

Pharmacokinetic studies to assess the potential of galantamine for interaction with cimetidine, ranitidine, ketoconazole, erythromycin, paroxetine, warfarin and digoxin were limited to short-term, mostly single-dose studies in young healthy volunteers. Similar studies in elderly patients were not done.

Galantamine plasma levels may be increased in patients with moderate to severe hepatic impairment. In patients with moderately impaired hepatic function (Child-Pugh score of 7-9), based on pharmacokinetic modelling, dosing with REMINYL tablets should begin with 4 mg once daily in the morning, preferably with food, for at least 1 week. Then the dosage should be increased to 4 mg twice a day for at least 4 weeks. For REMINYL ER extended release capsules, based on pharmacokinetic modelling, dosing should begin with 8 mg every other day in the morning, preferably with food, for at least 1 week. Then the dosage should be increased to 8 mg once daily for at least 4 weeks. In these patients, daily doses should not exceed a total of 16 mg/day. Since no data are available on the use of REMINYL or REMINYL ER in patients with severe hepatic impairment (Child-Pugh score of 10-15), REMINYL and REMINYL ER are not recommended for this population (see Warnings and Precautions).

Dose escalation for elderly patients (>85 years old) with low body weight (especially females) or serious comorbid diseases should be undertaken with particular caution.

Concomitant Treatment: In patients treated with potent CYP2D6 or CYP3A4 inhibitors, dose reductions can be considered.

The dosage of REMINYL shown to be effective in controlled clinical trials is 16-32 mg/day given as twice daily dosing. As the dose of 32 mg/day is less well tolerated than lower doses and does not provide increased effectiveness, the recommended dose range is 16-24 mg/day. The dose of 24 mg/day did not provide a statistically significant greater clinical benefit than 16 mg/day. It is possible, however, that a daily dose of 24 mg of REMINYL might provide additional benefit for some patients.

The recommended starting dose is 8 mg/day. The dose should be increased to the initial maintenance dose of 16 mg/day after 4 weeks. If this initial maintenance dose is well tolerated, a further increase to 24 mg/day may be considered only after a minimum of 4 weeks at 16 mg/day.

The abrupt withdrawal of REMINYL or REMINYL ER in those patients who had been receiving doses in the effective range was not associated with an increased frequency of adverse events in comparison with those continuing to receive the same doses of that drug. The beneficial effects of REMINYL and REMINYL ER are lost, however, when the drug is discontinued.

For patients with renal impairment (creatinine clearance of 9 to 60 mL/min), dose escalation should proceed cautiously and the maintenance dose should generally not exceed 16 mg/day. Since no data are available on the use of REMINYL or REMINYL ER in patients with a creatinine clearance less than 9 mL/min, REMINYL and REMINYL ER are not recommended for this population (see Warnings and Precautions).

In a population of cognitively-impaired individuals, safe use of this and all other medications may require supervision.

No clinically relevant abnormalities in laboratory values were observed. In a cardiovascular safety clinical trial (GAL-USA-16), pauses greater than two seconds were more common in galantamine-treated patients than in placebo-treated patients during the dose-escalation period (see Warnings and Precautions).

upper and lower GI bleeding.

Other adverse events from post-approval controlled and uncontrolled clinical trials and post-marketing experience observed in patients treated with REMINYL include:

Because clinical trials are conducted under very specific conditions, the adverse drug reaction rates observed in the clinical trials may not reflect the rates observed in practice and should not be compared to the rates in the clinical trials of another drug. Adverse drug reaction information from clinical trials is useful for identifying drug-related adverse events and for approximating rates.

A total of 2287 patients with mild to moderate Alzheimer's disease were treated with REMINYL in Phase III controlled clinical studies using either a 1-week or 4-week dose-escalation period, and 761 patients received REMINYL 24 mg/day, the maximum recommended maintenance dose. The number of patients who completed the studies was 1686 (72%). The mean duration of treatment for all REMINYL groups was 130 days (range 1-214 days).

Adverse Events Reported in at Least 2% of Patients with Alzheimer's Disease Administered REMINYL or REMINYL ER and at a Frequency Greater Than Placebo

hypokalemia.

Some of these adverse events may be attributable to cholinomimetic properties of REMINYL or in some cases may represent manifestations or exacerbations of the underlying disease processes common in the elderly population.

behavioural disturbances including agitation, aggression and hallucinations.

Frequent: hypertension; Infrequent: postural hypotension, hypotension, dependent edema, cardiac failure, myocardial ischemia or infarction.

elevated liver enzymes, hepatitis.

Infrequent: AV block, palpitation, atrial arrhythmias including atrial fibrillation and supraventricular tachycardia, QTc prolonged, bundle branch block, T-wave inversion, ventricular tachycardia; Rare: severe bradycardia.

Frequent: incontinence; Infrequent: hematuria, micturition frequency, cystitis, urinary retention, nocturia, renal calculi.

Frequent: flatulence; Infrequent: gastritis, melena, dysphagia, rectal hemorrhage, dry mouth, saliva increased, diverticulitis, gastroenteritis, hiccup; Rare: esophageal perforation.

REMINYL has been administered to 3055 patients with Alzheimer's disease during clinical trials worldwide.

A total of 2357 patients received galantamine in placebo-controlled trials and 761 patients with Alzheimer's disease received galantamine 24 mg/day, the maximum recommended maintenance dose. About 1000 patients received galantamine for at least one year and approximately 200 patients received galantamine for two years. To establish the rate of adverse events, data from all patients for any dose of REMINYL in 8 placebo-controlled trials and 6 open-label extension trials were pooled. The methodology to gather and codify these adverse events was standardized across trials, using WHO terminology. All events occurring in approximately 0.1% of patients are included, except for those already listed elsewhere in labelling, WHO terms too general to be informative, or relatively minor events. Events are classified by body system and listed using the following definitions: frequent adverse events—those occurring in at least 1/100 patients; infrequent adverse events—those occurring in 1/100 to 1/1000 patients; rare—those occurring in 1/1000 to 1/10 000 patients; very rare—those occurring in fewer than 1/10 000 patients. These adverse events are not necessarily related to REMINYL treatment and in most cases were observed at a similar frequency in placebo-treated patients in the controlled studies.

The frequencies of certain cardiovascular-related adverse events, including syncope, hypertension, arrhythmia and bundle branch block were increased in patients treated with galantamine compared to placebo. The increase was due primarily to events that occurred in the subgroup of Alzheimer's patients with concomitant cerebrovascular disease. Patients with Alzheimer's disease and concomitant cerebrovascular disease who were treated with galantamine experienced syncope (3%), hypertension (4%), arrhythmia (3%) and bundle branch block (2%), but these events were not reported in the placebo group.

In the vascular dementia subgroup syncope was reported for 2% of patients treated with galantamine and 2% of patients treated with placebo; hypertension was reported for 5% of patients treated with galantamine and 2% of patients treated with placebo. Arrhythmia and bundle branch block adverse events were not reported in the vascular dementia subgroup.

In the entire study population the most common treatment-emergent adverse events (nausea, dizziness, vomiting, abdominal pain, diarrhea, fatigue and upper respiratory tract infection) were consistent with what has been observed in previous REMINYL studies involving Alzheimer's disease patients (see Action and Clinical Pharmacology, Special Populations and Conditions).

Infrequent: apathy, paroniria, paranoid reaction, libido increased, delirium; Rare: suicidal ideation, suicide attempt.

Infrequent: purpura, epistaxis, thrombocytopenia.

dehydration (including rare, severe cases leading to renal insufficiency and renal failure).

No data are available in children. Therefore, the use of REMINYL and REMINYL ER are not recommended in children under 18 years of age.

There is limited safety information for REMINYL and REMINYL ER in this patient population (see Warnings and Precautions, Special Populations).

Overdosage with cholinesterase inhibitors can result in cholinergic crisis characterized by severe nausea, vomiting, salivation, sweating, bradycardia, hypotension, respiratory depression, collapse and convulsions. Increasing muscle weakness is a possibility and may result in death if respiratory muscles are involved.

There have been post-marketing reports of Torsade de Pointes, QT prolongation, bradycardia, ventricular tachycardia and brief loss of consciousness in association with inadvertent overdoses of galantamine. In one case where the dose was known, eight 4 mg tablets (32 mg total) were ingested on a single day. 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, inadvertently ingested 160 mg and experienced sweating, vomiting, bradycardia, and near-syncope one hour later, which necessitated hospital treatment. His symptoms resolved within 24 hours.

Galantamine has a plasma half-life of approximately 7-8 hours. It is recommended that, in case of asymptomatic overdose, no further dose of REMINYL or REMINYL ER should be administered and the patient should be monitored.

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 overdosage. Intravenous atropine sulphate 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.

Each pink opaque, extended release capsule, containing white to off-white pellets, imprinted with “G 16”, contains: galantamine 16 mg as galantamine HBr. Nonmedicinal ingredients: diethyl phthalate, ethylcellulose, gelatin, hypromellose, polyethylene glycol, red ferric oxide, sugar spheres (sucrose and starch) and titanium dioxide. Bottles of 30.

Each white opaque, extended release capsule, containing white to off-white pellets, imprinted with “G 8”, contains: galantamine 8 mg as galantamine HBr. Nonmedicinal ingredients: diethyl phthalate, ethylcellulose, gelatin, hypromellose, polyethylene glycol, sugar spheres (sucrose and starch) and titanium dioxide. Bottles of 30.

Each caramel opaque, extended release capsule, containing white to off-white pellets, imprinted with “G 24”, contains: galantamine 24 mg as galantamine HBr. Nonmedicinal ingredients: diethyl phthalate, ethylcellulose, gelatin, hypromellose, polyethylene glycol, red ferric oxide, sugar spheres (sucrose and starch), titanium dioxide and yellow ferric oxide. Bottles of 30.

Each orange-brown, circular, biconvex, film-coated tablet, with the inscription “JANSSEN” on one side and “G12” on the other side, contains: galantamine 12 mg as galantamine HBr. Nonmedicinal ingredients: colloidal anhydrous silica, crospovidone, FD&C yellow #6 (also known as orange yellow S aluminum lake), hydroxypropyl methylcellulose (also known as hypromellose), lactose monohydrate, magnesium stearate, microcrystalline cellulose, propylene glycol, red ferric oxide, talc and titanium dioxide. Bottles of 60.

Each off-white, circular, biconvex, film-coated tablet, with the inscription “JANSSEN” on one side and “G4” on the other side, contains: galantamine 4 mg as galantamine HBr. Nonmedicinal ingredients: colloidal anhydrous silica, crospovidone, hydroxypropyl methylcellulose (also known as hypromellose), lactose monohydrate, magnesium stearate, microcrystalline cellulose, propylene glycol, talc, titanium dioxide and yellow ferric oxide. Bottles of 60.

Through their primary action, cholinesterase inhibitors 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). In controlled clinical studies with galantamine, patients with symptomatic peptic ulceration were excluded. Clinical studies of galantamine have shown no increase, relative to placebo, in the incidence of either peptic ulcer disease or gastrointestinal bleeding (see Adverse Reactions).

Galantamine, as a predictable consequence of its pharmacological properties, has been shown to produce nausea, vomiting and diarrhea, anorexia and weight loss. These effects appeared more frequently at higher doses (see Adverse Reactions), with nausea and vomiting being more prevalent in women and patients with lower body weight and correspondingly higher plasma drug concentrations. Females are more sensitive to the cholinergic adverse effects associated with cholinesterase inhibitors and in general are more likely to experience nausea and vomiting than are males. In most cases, these effects were of mild to moderate intensity and transient and have resolved during continued REMINYL treatment or upon treatment discontinuation.

Anesthesia: Galantamine, as a cholinesterase inhibitor, is likely to exaggerate succinylcholine-type muscle relaxation during anesthesia.

Cholinesterase inhibitors as well as Alzheimer's disease can be associated with significant weight loss. In controlled clinical trials, the use of REMINYL was associated with weight loss. Weight decrease occurred early during treatment and was related to dose. Weight loss of ≥7% occurred more frequently in patients treated with REMINYL and in female patients than in patients receiving placebo. Where weight loss may be of clinical concern, body weight should be monitored.

There is limited information on the pharmacokinetics of galantamine in hepatically impaired patients (see Action and Clinical Pharmacology). It is therefore recommended that dose escalation with REMINYL or REMINYL ER in Alzheimer's disease patients with hepatic impairment be undertaken with caution and under conditions of close monitoring for adverse effects (see Dosage and Administration, Special Populations). Since no data are available on the use of REMINYL or REMINYL ER in patients with severe hepatic impairment (Child-Pugh score of 10-15), REMINYL and REMINYL ER are not recommended for this population.

Like other cholinomimetic drugs, REMINYL and REMINYL ER should be prescribed with care for patients with a history of asthma or obstructive pulmonary disease.

The safety and effectiveness of REMINYL and REMINYL ER in any illness occurring in pediatric patients have not been established.

In a teratology 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 MRHD on a mg/m² basis) 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/m² basis) during the period of organogenesis.

The safety of REMINYL and REMINYL ER in pregnant women has not been established. REMINYL and REMINYL ER should not be used in women of childbearing potential unless, in the opinion of the physician, the potential benefit to the patient justifies the potential risk to the fetus.

There is limited information on the pharmacokinetics of galantamine in renally impaired patients (see Action and Clinical Pharmacology). It is therefore recommended that dose escalation with REMINYL or REMINYL ER in Alzheimer's disease patients with renal impairment (creatinine clearance of 9 to 60 mL/min) be undertaken with caution and under conditions of close monitoring for adverse effects (see Dosage and Administration, Special Populations). Since no data are available on the use of REMINYL or REMINYL ER in patients with a creatinine clearance of less than 9 mL/min, REMINYL and REMINYL ER are not recommended for this population.

Although not observed in clinical trials of galantamine, cholinomimetics may cause bladder outflow obstruction.

Seizures: In placebo-controlled trials with galantamine, cases of seizure were reported; there was no increase in incidence compared with placebo. Although cholinomimetics are believed to have some potential to cause seizures, seizure activity may also be a manifestation of Alzheimer's disease. The risk/benefit of REMINYL and REMINYL ER treatment for patients with a history of seizure disorder must therefore be carefully evaluated.

REMINYL and REMINYL ER have not been studied in patients with moderately severe or severe Alzheimer's disease, non-Alzheimer dementias or individuals with Parkinsonian features. The efficacy and safety of REMINYL and REMINYL ER in these patient populations is unknown.

Two randomized, double-blind, placebo-controlled efficacy and safety studies of 2 years' duration were completed in non-demented subjects with MCI. Individuals with MCI demonstrate isolated memory impairment greater than expected for their age and education, but do not meet current diagnostic criteria for Alzheimer's Disease. In these trials, REMINYL was not shown to be effective in patients with MCI. In the double-blind portion of these two trials, a total of 13 deaths in subjects on REMINYL (n=1026) were recorded and 1 death in subjects on placebo (n=1022); the reason for this difference is currently unknown. This difference in mortality has not been observed in REMINYL studies in Alzheimer's Disease. Approximately half of the REMINYL deaths appeared to have resulted from various vascular causes (myocardial infarction, stroke, and sudden death); other deaths appeared to have resulted from infection, suicide and cancer. There is no evidence of an increased risk of mortality when REMINYL is used in patients with mild to moderate Alzheimer's Disease.

There is limited information on the safety of galantamine treatment in patients with mild to moderate Alzheimer's disease and serious/significant comorbidity. The use of REMINYL and REMINYL ER in Alzheimer's disease patients with chronic illnesses common among the geriatric population, should be considered only after careful risk/benefit assessment and include close monitoring for adverse events. Dose escalation in this patient population should proceed with caution.

In controlled clinical studies, the number of patients aged 85 years or over who received REMINYL at therapeutic doses of 16 or 24 mg/day was 123. Of these patients, 70 received the maximum recommended dose of 24 mg/day. There is limited safety information for REMINYL in this patient population.

Since cholinomimetics as well as Alzheimer's disease can be associated with significant weight loss, caution is advised regarding the use of REMINYL and REMINYL ER in elderly patients with low body weight, especially in those ≥85 years old.

It is not known whether galantamine is excreted in human breast milk and therefore REMINYL and REMINYL ER should not be used in nursing mothers.

Because of their pharmacological action, cholinesterase inhibitors have vagotonic effects on the sinoatrial and atrioventricular nodes, leading to bradycardia and heart block. These actions may be particularly important to patients with “sick sinus syndrome” or other supraventricular cardiac conduction disorders, or to patients taking other drugs concomitantly which significantly slow heart rate. In clinical trials, patients with serious cardiovascular disease were excluded. Caution should be exercised in treating patients with active coronary artery disease or congestive heart failure. It is recommended that REMINYL and REMINYL ER not be used in patients with cardiac conduction abnormalities (except for right bundle branch block) including “sick sinus syndrome” and those with unexplained syncopal episodes.

In randomized controlled trials, bradycardia was reported at 2-3% for galantamine doses up to 24 mg/day compared with <1% for placebo, but was rarely severe and rarely led to treatment discontinuation. No increased incidence of heart block was observed at the recommended doses. Patients treated with galantamine up to 24 mg/day at the recommended dosing schedule showed a dose-related increase in risk of syncope (placebo, 0.7% [2/286]; 4 mg b.i.d., 0.4% [3/692]; 8 mg b.i.d., 1.3% [7/552]; 12 mg b.i.d., 2.2% [6/273]).

A 6-week cardiovascular safety clinical trial (GAL-USA-16; n=139) was performed to investigate the effect of galantamine at doses up to 32 mg/day. This dosing regimen was: 8 mg/day in Week 1, 16 mg/day in Week 2, 24 mg/day in Weeks 3 and 4, and 32 mg/day in Weeks 5 and 6. Heart block/pauses greater than two seconds were more common in galantamine-treated patients than in placebo-treated patients. It should be noted that a forced 1-week dose escalation was used in this study, which is not recommended. Whether these cardiac effects are attenuated by slower titration rates is not known. Particular caution is warranted during titration where the majority of pauses occurred in the above study.

Galantamine is a low-clearance drug (plasma clearance of approximately 300 mL/min) with a moderate volume of distribution (average Vdss of 175 L) after a one-hour i.v. infusion of 8 mg galantamine in 12 healthy males.

The plasma protein binding of galantamine is 18% at therapeutically relevant concentrations. In whole blood, galantamine is mainly distributed to blood cells (52.7%) and plasma water (39.0%), whereas the fraction of galantamine bound to plasma proteins is only 8.4%. The blood-to-plasma concentration ratio of galantamine is 1.2.

After oral intake of a single 8 mg galantamine solution in 12 healthy males, absorption is rapid, with a peak plasma concentration (C_max) of 43±13 ng/mL, which is reached after 1.2 hours (T_max), and a mean AUC_∞ of 427±102 ng·h/mL.

The absolute oral bioavailability of galantamine is 88.5%. Bioavailability of the tablet was the same as the bioavailability of an oral solution in 27 healthy males. Food did not affect the AUC of galantamine but C_max decreased by 25% and T_max was delayed by 1.5 hours after repeated oral dosing of 12 mg galantamine b.i.d. in 24 healthy elderly subjects.

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

In a steady-state bioavailability study, galantamine hydrobromide extended release capsules, 24 mg once daily, were shown to be bioequivalent to the 12 mg twice-daily galantamine tablets with respect to AUC_24h and C_min. The C_max value of the 24 mg once-daily extended release capsule, which is reached after 4.4 hours, was about 24% lower than that of the 12 mg twice-daily tablet. Food had no effect on the steady-state bioavailability of the 24 mg extended release capsules. In a dose-proportionality study of galantamine extended release capsules in healthy elderly and young subjects, steady-state plasma concentrations were achieved within 6 days at all doses (8 mg, 16 mg, and 24 mg) in both age groups. Steady-state pharmacokinetics were dose-proportional within the studied dose range of 8 mg to 24 mg in both age groups.

Approximately 7% of the normal population has a genetic variation that leads to reduced levels of activity of the 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_max 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 III 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 due to observed inter-patient variability.

The frequencies of certain cardiovascular-related adverse events, including syncope, hypertension, arrhythmia and bundle branch block, were increased in patients treated with galantamine compared to placebo. Analyses of treatment-emergent adverse events by diagnostic subgroup indicated that the increase was due primarily to events that occurred in the subgroup of patients with AD+CVD (see Adverse Reactions).

The elimination of galantamine is bi-phasic, with a terminal half-life in the order of 7-8 hours in young healthy subjects (n=4 males). Two studies in healthy elderly subjects indicated that the terminal half-life of galantamine is 8.5 hours (n=13 males and 16 females) and 9.7 hours (n=10 males and 14 females) after administering a single oral dose of 10 mg galantamine. Up to 8 hours post-dose, unchanged galantamine accounted for 39-77% of the total radioactivity in the plasma, and galantamine glucuronide accounted for 14-24%. Seven days after a single oral dose of 4 mg 3H-galantamine, 93-99% of the radioactivity had been recovered, with about 95% in urine and about 5% in 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. and oral administration, about 20% of the dose was excreted as unchanged galantamine in the urine in 24 hours, with a renal clearance of about 65 mL/min, which represents 20-25% of the total plasma clearance of about 300 mL/min.

No specific pharmacokinetic study was performed to investigate the gender differences. A population pharmacokinetic analysis (n=539 males and 550 females) suggests that galantamine clearance is about 20% lower in females than in males, which is explained by lower body weight in females.

Galantamine is metabolized by hepatic cytochrome P450 enzymes, glucuronidated and excreted unchanged in the urine. In vitro studies indicate that cytochrome CYP2D6 and CYP3A4 are the major cytochrome P450 isoenzymes involved in the metabolism of galantamine, and inhibitors of both pathways increase oral bioavailability of galantamine modestly (see Drug Interactions, Drug-Drug Interactions). O-demethylation, mediated by CYP2D6 is 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.

Following a single 4 mg dose of galantamine, the pharmacokinetics of galantamine in subjects with mild hepatic impairment (n=8; Child-Pugh score of 5-6) were similar to those in healthy subjects. In patients with moderate hepatic impairment (n=8; Child-Pugh score of 7-9), AUC and half-life of galantamine were increased by about 30% compared to normal subjects (see Warnings and Precautions and Dosage and Administration).

A randomized, double-blind, placebo-controlled clinical trial (GAL-INT-6) was conducted in a study population consisting of two different types of dementia patients: patients with vascular dementia (VaD) and patients with Alzheimer’s disease and concomitant cerebrovascular disease (AD+CVD).

In patients with renal insufficiency, elimination of galantamine decreases with decreasing creatinine clearance. Following a single 8 mg dose of galantamine, AUC increased by 37% and 67% in moderately (n=8; creatinine clearance of 30 to 60 mL/min/1.73 m²) and severely (n=9; creatinine clearance of 5 to 29 mL/min/1.73 m²) renal-impaired patients compared to normal volunteers (n=8) (see Warnings and Precautions and Dosage and Administration).

Although the etiology of cognitive impairment in Alzheimer’s disease 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 cholinesterase inhibitor. 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 cholinesterase inhibition. It has also been postulated, based on in vitro data, that galantamine enhances the action of acetylcholine through binding to an allosteric site on the nicotinic receptors (see Warnings and Precautions). The clinical relevance to humans of these in vitro findings is unknown.

If these mechanisms are 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.

Data from clinical trials in patients indicate that there is a difference in total clearance after oral administration between patients with Alzheimer’s disease and healthy subjects (13.2 L/h versus 19.4 L/h) based on pooled population analysis. Therefore, the plasma concentrations of galantamine in elderly patients (median age 75) with Alzheimer’s disease are 30-40% higher than in healthy young subjects (median age 28).

The results of this single study do not support regulatory endorsement of an indication for either VaD or AD+CVD patient populations.

There are no criteria established for making a differential diagnosis between patients with Alzheimer’s disease and patients with concomitant cerebrovascular disease in clinical practice. Under the currently approved Canadian indication, REMINYL is available for the treatment of patients with mild to moderate Alzheimer’s disease, which in clinical practice is likely to also include the treatment of patients with Alzheimer’s disease and concomitant cerebrovascular disease.

Pharmacokinetic differences due to race have not been identified in a population pharmacokinetic analysis (n=1029 White, 24 Black, 13 Asian and 23 other).

Efficacy results for the entire study population showed that there were statistically significant treatment effects on both primary endpoints (ADAS-cog and CIBIC-Plus) for galantamine-treated patients compared to placebo. Because the study population consisted of two different types of dementia patients, these results cannot be extrapolated to either patient population. Pre-specified analyses, conducted on the two subgroups for exploratory purposes, indicated that for both primary endpoints treatment differences for galantamine compared to placebo were not statistically significant for patients with VaD (galantamine n=171, placebo n=81), but were statistically significant for patients with AD+CVD (galantamine n=188, placebo n=97).

Confounding factors that preclude regulatory endorsement of an Indication for either of the two dementia patient populations include:

1. Trial Design:

   
   

   1. The study population consisted of two clinically different dementia patient populations, included in a ratio of approximately 1:1. Separate exploratory analyses of efficacy data from the diagnostic subgroups were pre-specified in the study statistical analysis plan but exploratory analyses are not regarded as confirmatory and therefore are not supportive of an indication.

      
      

   2. The validity of the assessment scales used in this study (ADAS-cog and CIBIC-Plus) has not been established for evaluating treatment effects in VaD, but has been established for Alzheimer’s disease.

      
      

   3. There are no established diagnostic criteria in clinical practice for the identification of patients with AD+CVD. In the primary care setting, without the use of radiological imaging (CAT or MRI), these patients may be difficult to distinguish from Alzheimer’s disease patients.

      
      

2. Data Analyses:

   
   

   1. The overall positive efficacy results for the entire study population cannot be extrapolated to either of the two patient subgroups.

      
      

   2. The significance of the negative outcome from the exploratory analysis of the VaD patient subgroup is not known, in view of the unconfirmed validity of these assessment scales for evaluating efficacy in VaD.

      
      

   3. Positive results from the exploratory analysis of the subgroup of patients with AD+CVD, in a single study, are not sufficient to support a claim of efficacy for these patients.

VaD patients (n=282) were diagnosed according to NINDS-AIREN criteria for probable vascular dementia. Patients with AD+CVD (n=255) were required to meet NINCDS-ADRDA criteria for possible Alzheimer’s disease and have radiological evidence (CAT or MRI) of relevant cerebrovascular disease for inclusion in the study. Patients were treated for 26 weeks with galantamine 12 mg b.i.d. (VaD n=173; AD+CVD n=186) or placebo (VaD n=82; AD+CVD n=86).