1.1 Alzheimer’s Disease

Rivastigmine tartrate capsules are indicated for the treatment of mild to moderate dementia of the Alzheimer's type.

1.2 Parkinson’s Disease Dementia

Rivastigmine tartrate capsules are indicated for the treatment of mild to moderate dementia associated with Parkinson’s disease.

2.1 Recommended Dosing

Rivastigmine tartrate capsules should be taken with meals in divided doses in the morning and evening.

Alzheimer’s Disease

The dosage of Rivastigmine tartrate capsules shown to be effective in controlled clinical trials in Alzheimer’s disease is 6 mg to 12 mg per day, administered twice a day (daily doses of 3 mg to 6 mg twice a day). There is evidence from the clinical trials that doses at the higher end of this range may be more beneficial.

Initial Dose

Initiate treatment with the 1.5 mg twice a day with Rivastigmine tartrate capsules.

Dose Titration

After a minimum of 2 weeks and if well tolerated, increase the dose to 3 mg twice a day. Subsequent increases to 4.5 mg twice a day and 6 mg twice a day should be attempted after a minimum of 2 weeks at the previous dose and if well tolerated. The maximum dose is 6 mg twice a day (12 mg per day).

Parkinson’s Disease Dementia

The dosage of Rivastigmine tartrate capsules shown to be effective in the single controlled clinical trial conducted in dementia associated with Parkinson’s disease is 3 mg to 12 mg per day, administered twice a day (daily doses of 1.5 mg to 6 mg twice a day).

Initial Dose

Initiate treatment with the 1.5 mg twice a day with Rivastigmine tartrate capsules.

Dose Titration

After a minimum of 4 weeks and if well tolerated, increase the dose to 3 mg twice a day. Subsequent increases to 4.5 mg twice a day and 6 mg twice a day should be attempted after a minimum of 4 weeks at the previous dose and if well tolerated. The maximum dose is 6 mg twice a day (12 mg per day).

Interruption of Treatment

If adverse effects (e.g., nausea, vomiting, abdominal pain, loss of appetite) cause intolerance during treatment, the patient should be instructed to discontinue treatment for several doses and then restart at the same or next lower dose level.

If dosing is interrupted for 3 days or fewer, restart treatment with the same or lower dose of Rivastigmine tartrate capsules. If dosing is interrupted for more than 3 days, treatment should be restarted with 1.5 mg twice a day and titrated as described above [see Warnings and Precautions (5.1)].

2.2 Dosing in Specific Populations

Dosing Modifications in Patients with Renal or Hepatic Impairment

Pharmacokinetic studies of oral rivastigmine in patients with moderate to severe renal impairment (glomerular filtration rate [GFR] <50 mL/min) and mild to moderate hepatic impairment (Child-Pugh score 5 to 9) showed reduced clearance of the drug [see Use in Specific Populations (8.6, 8.7), Clinical Pharmacology (12.3)]. Accordingly, such patients may be able to only tolerate lower doses. No data are available on the use of rivastigmine in patients with severe hepatic impairment.

Dosing Modifications in Patients with Low Body Weight

Because rivastigmine blood levels vary with body weight [see Use in Specific Populations (8.8), Clinical Pharmacology (12.3)], careful titration and monitoring should be performed in patients with low body weight. In patients with low body weight (less than 50 kg), monitor closely for toxicities (e.g., excessive nausea, vomiting), and consider reducing the dose if such toxicities develop.

2.3 Important Administration Instructions

Rivastigmine tartrate oral solution and Rivastigmine tartrate capsules may be interchanged at equal doses.

3.1 Rivastigmine Tartrate Capsules

Rivastigmine tartrate Capsules equivalent to 1.5 mg, 3 mg, 4.5 mg, or 6 mg of rivastigmine base are available as follows:

1.5 mg Capsule – pale yellow opaque / pale yellow opaque size “2” hard gelatin capsules radially imprinted with “B” on cap and “793” on body with black ink, filled with white to off-white free flowing powder.

3 mg Capsule – orange opaque / orange opaque size “2” hard gelatin capsules radially imprinted with “B” on cap and “794” on body with black ink, filled with white to off-white free flowing powder.

4.5 mg Capsule – coral red opaque / coral red opaque size “2” hard gelatin capsules radially imprinted with “B” on cap and “795” on body with black ink, filled with white to off-white free flowing powder.

6 mg Capsule – orange opaque / coral red opaque size “2” hard gelatin capsules radially imprinted with “B” on cap and “796” on body with black ink, filled with white to off-white free flowing powder.

5.1 Gastrointestinal Adverse Reactions

Rivastigmine tartrate can cause gastrointestinal adverse reactions, including significant nausea, vomiting, diarrhea, anorexia/decreased appetite, and weight loss. Dehydration may result from prolonged vomiting or diarrhea and can be associated with serious outcomes. The incidence and severity of these reactions are dose-related [see Adverse Reactions (6.1)]. For this reason, patients should always be started at a dose of 1.5 mg twice a day and titrated to their maintenance dose.

If treatment is interrupted for longer than 3 days, treatment should be reinitiated with the lowest daily dose [see Dosage and Administration (2.1)] to reduce the possibility of severe vomiting and its potentially serious sequelae (e.g., there has been one postmarketing report of severe vomiting with esophageal rupture following inappropriate reinitiation of treatment with a 4.5-mg dose after 8 weeks of treatment interruption).

Inform caregivers to monitor for gastrointestinal adverse reactions and to inform the physician if they occur. It is critical to inform caregivers that if therapy has been interrupted for more than 3 days because of intolerance, the next dose should not be administered without contacting the physician regarding proper retitration.  

5.2 Hypersensitivity Reactions of the Skin

There have been isolated postmarketing reports of patients experiencing disseminated hypersensitivity reactions of the skin when administered rivastigmine irrespective of the route of administration (oral or transdermal). Treatment should be discontinued if disseminated hypersensitivity reaction of the skin occurs [see Contraindications (4)]. Patients and caregivers should be instructed accordingly [see Patient Counseling Information(17)].

In patients who develop application site reactions suggestive of allergic contact dermatitis to rivastigmine tartrate patch and who still require rivastigmine, treatment should be switched to oral rivastigmine only after negative allergy testing and under close medical supervision. It is possible that some patients sensitized to rivastigmine by exposure to rivastigmine patch may not be able to take rivastigmine in any form.

5.3 Other Adverse Reactions from Increased Cholinergic Activity

Neurologic Effects  

Extrapyramidal Symptoms: Cholinomimetics, including rivastigmine may exacerbate or induce extrapyramidal symptoms. Worsening of parkinsonian symptoms, particularly tremor, has been observed in patients with dementia associated with Parkinson’s disease who were treated with rivastigmine tartrate capsules.

Seizures: Drugs that increase cholinergic activity are believed to have some potential for causing seizures. However, seizure activity also may be a manifestation of Alzheimer's disease.

Peptic Ulcers/Gastrointestinal Bleeding  

Cholinesterase inhibitors, including rivastigmine, may be expected to increase gastric acid secretion due to increased cholinergic activity. Monitor patients using Rivastigmine tartrate capsules for symptoms of active or occult gastrointestinal bleeding, especially those at increased risk for developing ulcers, e.g., those with a history of ulcer disease or those receiving concurrent nonsteroidal anti-inflammatory drugs (NSAIDs). Clinical studies of rivastigmine have shown no significant increase, relative to placebo, in the incidence of either peptic ulcer disease or gastrointestinal bleeding.

Use with Anesthesia  

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

Cardiac Conduction Effects  

Because rivastigmine increases cholinergic activity, use of rivastigmine may have vagotonic effects on heart rate (e.g., bradycardia). The potential for this action may be particularly important in patients with sick sinus syndrome or other supraventricular cardiac conduction conditions. In clinical trials, rivastigmine was not associated with any increased incidence of cardiovascular adverse events, heart rate or blood pressure changes, or ECG abnormalities. Syncopal episodes have been reported in 3% of patients receiving 6 mg to 12 mg per day of rivastigmine tartrate, compared to 2% of placebo patients.

Genitourinary Effects  

Although not observed in clinical trials of rivastigmine, drugs that increase cholinergic activity may cause urinary obstruction.

Pulmonary Effects  

Drugs that increase cholinergic activity, including rivastigmine, should be used with care in patients with a history of asthma or obstructive pulmonary disease.

5.4 Impairment in Driving or Use of Machinery

Dementia may cause gradual impairment of driving performance or compromise the ability to use machinery. The administration of rivastigmine may also result in adverse reactions that are detrimental to these functions. During treatment with rivastigmine tartrate capsules, routinely evaluate the patient’s ability to continue driving or operating machinery.

6.1 Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

Rivastigmine tartrate has been administered to over 5,297 individuals during clinical trials worldwide. Of these, 4,326 patients have been treated for at least 3 months, 3,407 patients have been treated for at least 6 months, 2,150 patients have been treated for 1 year, 1,250 patients have been treated for 2 years, and 168 patients have been treated for over 3 years. With regard to exposure to the highest dose, 2,809 patients were exposed to doses of 10 mg to 12 mg, 2,615 patients treated for 3 months, 2,328 patients treated for 6 months, 1,378 patients treated for 1 year, 917 patients treated for 2 years, and 129 patients treated for over 3 years.

Mild to Moderate Alzheimer’s Disease

Most Commonly Observed Adverse Reactions

The most common adverse reactions, defined as those occurring at a frequency of at least 5% and twice the placebo rate, are largely predicted by rivastigmine tartrate's cholinergic effects. These include nausea, vomiting, anorexia, dyspepsia, and asthenia.

Gastrointestinal Adverse Reactions

Rivastigmine tartrate use is associated with significant nausea, vomiting, and weight loss [see Warnings and Precautions (5.1)].

Discontinuation Rates

The rate of discontinuation due to adverse events in controlled clinical trials of rivastigmine tartrate was 15% for patients receiving 6 mg to 12 mg per day compared to 5% for patients on placebo during forced weekly dose titration. While on a maintenance dose, the rates were 6% for patients on rivastigmine tartrate compared to 4% for those on placebo.

The most common adverse reactions leading to discontinuation, defined as those occurring in at least 2% of patients and at twice the incidence seen in placebo patients, are shown in Table 1.

Table 1 Most Frequent Adverse Reactions Leading to Withdrawal from Clinical Trials during Titration and Maintenance in Patients Receiving 6 mg to 12 mg per day Rivastigmine Tartrate Using a Forced-Dose Titration

Adverse Reactions Observed at an Incidence of at Least 2%  

Table 2 lists treatment-emergent signs and symptoms that were reported in at least 2% of patients in placebo-controlled trials and for which the rate of occurrence was greater for patients treated with rivastigmine tartrate doses of 6 mg to 12 mg per day than for those treated with placebo. The prescriber should be aware that these figures cannot be used to predict the frequency of adverse events in the course of usual medical practice when patient characteristics and other factors may differ from those prevailing during clinical studies. Similarly, the cited frequencies cannot be directly compared with figures obtained from other clinical investigations involving different treatments, uses, or investigators. An inspection of these frequencies, however, does provide the prescriber with one basis by which to estimate the relative contribution of drug and nondrug factors to the adverse event incidences in the population studied.

In general, adverse reactions were less frequent later in the course of treatment.

No systematic effect of race or age could be determined from the incidence of adverse events in the controlled studies. Nausea, vomiting and weight loss were more frequent in women than men.

Table 2 Proportion of Adverse Reactions Observed with a Frequency of ≥2% and at a Rate Greater than Placebo in Clinical Trials

*Nausea and Vomiting: In the controlled clinical trials, 47% of the patients treated with a rivastigmine tartrate dose in the therapeutic range of 6 mg to 12 mg per day (n=1189) developed nausea (compared with 12% in placebo). A total of 31% of rivastigmine tartrate -treated patients developed at least 1 episode of vomiting (compared with 6% for placebo). The rate of vomiting was higher during the titration phase (24% versus 3% for placebo) than in the maintenance phase (14% versus 3% for placebo). The rates were higher in women than men. Five percent of patients discontinued for vomiting, compared to less than 1% for patients on placebo. Vomiting was severe in 2% of rivastigmine tartrate-treated patients and was rated as mild or moderate each in 14% of patients. The rate of nausea was higher during the titration phase (43% versus 9% for placebo) than in the maintenance phase (17% versus 4% for placebo).

**Weight Decreased: In the controlled trials, approximately 26% of women on high doses of rivastigmine tartrate (greater than 9 mg per day) had weight loss equal to or greater than 7% of their baseline weight compared to 6% in the placebo-treated patients. About 18% of the males in the high-dose group experienced a similar degree of weight loss compared to 4% in placebo-treated patients. It is not clear how much of the weight loss was associated with anorexia, nausea, vomiting, and the diarrhea associated with the drug.

***Anorexia: In the controlled clinical trials, of the patients treated with a rivastigmine tartrate dose of 6 mg to 12 mg per day, 17% developed anorexia compared to 3% of the placebo patients. Neither the time course nor the severity of the anorexia is known.

 
Mild to Moderate Parkinson’s Disease Dementia
Rivastigmine tartrate has been administered to 779 individuals during clinical trials worldwide. Of these, 663 patients have been treated for at least 3 months, 476 patients have been treated for at least 6 months, and 313 patients have been treated for 1 year.
Most Commonly Observed Adverse Reactions
The most common adverse events, defined as those occurring at a frequency of at least 5% and twice the placebo rate, are largely predicted by rivastigmine tartrate's cholinergic effects. These include nausea, vomiting, tremor, anorexia, and dizziness.

Discontinuation Rates
The rate of discontinuation due to adverse events in the single placebo-controlled trial of rivastigmine tartrate was 18.2% for patients receiving 3 mg to 12 mg per day compared to 11.2% for patients on placebo during the 24-week study.

The most frequent adverse events that led to discontinuation from this study, defined as those occurring in at least 1% of patients receiving rivastigmine tartrate and more frequent than those receiving placebo, were nausea (3.6% rivastigmine tartrate versus 0.6% placebo), vomiting (1.9% rivastigmine tartrate versus 0.6% placebo), and tremor (1.7% rivastigmine tartrate versus 0.0% placebo).

Adverse Reactions Observed at an Incidence of at Least 2%
Table 3 lists treatment-emergent signs and symptoms that were reported in at least 2% of patients in a single placebo-controlled trial and during the first 24 weeks of a 76-week open-label active-controlled trial for which the rate of occurrence was greater for patients treated with rivastigmine tartrate doses of 3 mg to 12 mg per day than for those treated with placebo in the placebo-controlled trial. The prescriber should be aware that these figures cannot be used to predict the frequency of adverse events in the course of usual medical practice when patient characteristics and other factors may differ from those prevailing during clinical studies. Similarly, the cited frequencies cannot be directly compared with figures obtained from other clinical investigations involving different treatments, uses, or investigators. An inspection of these frequencies, however, does provide the prescriber with 1 basis by which to estimate the relative contribution of drug and non-drug factors to the adverse event incidences in the population studied.
 
In general, adverse reactions were less frequent later in the course of treatment.

Table 3 Proportion of Adverse Reactions Observed at a Frequency ≥2% and Occurring at Rate Greater than Placebo in Clinical Trials

*Parkinson’s disease (worsening) in the active-controlled study was assessed by reported pre-identified adverse events (tremor, cogwheel rigidity, fall), each of them listed with corresponding frequencies.

Other Adverse Events Observed During Clinical Trials  

Mild to Moderate Alzheimer’s Disease  

Treatment-emergent signs and symptoms that occurred during 8 controlled clinical trials and 9 open-label trials in North America, Western Europe, Australia, South Africa, and Japan were recorded as adverse events by the clinical investigators using terminology of their own choosing. To provide an overall estimate of the proportion of individuals having similar types of events, the events were grouped into a smaller number of standardized categories using a modified WHO dictionary, and event frequencies were calculated across all studies. These categories are used in the listing below. The frequencies represent the proportion of 5,297 patients from these trials who experienced that event while receiving rivastigmine tartrate. All adverse events occurring in at least 6 patients (approximately 0.1%) are included, except for those already listed elsewhere in labeling, WHO terms too general to be informative, relatively minor events, or events unlikely to be drug-caused.

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 1/1,000 patients. These adverse events are not necessarily related to rivastigmine tartrate treatment and in most cases were observed at a similar frequency in placebo-treated patients in the controlled studies.

Autonomic Nervous System: Infrequent: Increased saliva.

Body as a Whole: Frequent: Allergy, hot flushes.

Cardiovascular System: Frequent: Hypotension, postural hypotension.

Central and Peripheral Nervous System: Frequent: Abnormal gait, ataxia, paresthesia, convulsions. Infrequent: Dysphonia, hypoesthesia, migraine, nystagmus.

Gastrointestinal System: Frequent: Gastritis, constipation, flatulence. Infrequent: Gastric ulcer, gastroesophageal reflux, GI hemorrhage, hernia, melena, rectal hemorrhage, duodenal ulcer, hematemesis, pancreatitis.

Hearing and Vestibular Disorders: Frequent: Tinnitus.

Heart Rate and Rhythm Disorders: Frequent: Atrial fibrillation, bradycardia, palpitation. Infrequent: AV block, sick sinus syndrome, supraventricular tachycardia, extrasystoles, tachycardia.

Liver and Biliary System Disorders: Infrequent: Abnormal hepatic function tests.

Metabolic and Nutritional Disorders: Frequent: Dehydration, hypokalemia. Infrequent: Hyponatremia.

Musculoskeletal Disorders: Infrequent: Muscle weakness.

Myo-, Endo-, Pericardial and Valve Disorders: Frequent: Angina pectoris, myocardial infarction.

Psychiatric Disorders: Frequent: Confusion. Infrequent: Apathy, suicide attempt, increased libido, suicidal ideation.

Reproductive Disorders (Female and Male): Infrequent: Breast pain.

Resistance Mechanism Disorders: Infrequent: Herpes simplex, otitis media. Respiratory System: Infrequent: Bronchospasm.

Skin and Appendages: Frequent: Rashes of various kinds (maculopapular, eczema, bullous, exfoliative, psoriaform, erythematous). Infrequent: Urticaria, contact dermatitis.

Urinary System Disorders: Frequent: Hematuria. Infrequent: Acute renal failure, dysuria. Vascular (extracardiac) Disorders: Infrequent: Peripheral ischemia, intracranial hemorrhage. Vision Disorders: Frequent: Cataract. Infrequent: Diplopia, glaucoma.

White Cell and Resistance Disorders: Infrequent: Lymphadenopathy.

Mild to Moderate Parkinson’s Disease Dementia  

Additional treatment-emergent adverse events in patients with Parkinson’s disease dementia occurring in at least 1 patient (approximately 0.3%) are listed below, excluding events that are already listed above for the dementia of the Alzheimer’s type or elsewhere in labeling, WHO terms too general to be informative, relatively minor events, or events unlikely to be drug-caused. 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 1/1,000 patients. These adverse events are not necessarily related to rivastigmine tartrate treatment and in most cases were observed at a similar frequency in placebo-treated patients in the controlled studies.

Central and Peripheral Nervous System: Frequent: Transient ischemic attack. Gastrointestinal System: Frequent: Dyspepsia. Infrequent: Fecaloma, dysphagia.

General Disorders and Administration Site Conditions: Frequent: Chest pain.

Liver and Biliary System Disorders: Infrequent: Elevated gamma-glutamyltransferase level. Musculoskeletal Disorders: Frequent: Back pain. Infrequent: Muscle stiffness.

Psychiatric Disorders: Frequent: Agitation, depression.

Respiratory System: Frequent: Dyspnea. Infrequent: Cough.

Urinary System Disorders: Infrequent: Urinary incontinence.

Vision Disorders: Infrequent: Blurred vision.  

6.2 Postmarketing Experience

Voluntary reports of adverse events temporally associated with rivastigmine tartrate that have been received since market introduction that are not listed above, and that may or may not be causally related to the drug include the following:

       Hepatobiliary Disorders: Hepatitis.

        Psychiatric Disorders: Aggression.

Skin and Appendages: Stevens-Johnson syndrome, disseminated cutaneous hypersensitivity reactions.

7.1 Cholinomimetic and Anticholinergic Drugs

Increased cholinergic effects may be expected when rivastigmine is given with other cholinomimetic drugs. Rivastigmine may also interfere with the activity of anticholinergic medications. Avoid concomitant use of rivastigmine with drugs having these pharmacologic effects unless deemed clinically necessary.

8.1 Pregnancy

Pregnancy Category B

There are no adequate and well-controlled studies in pregnant women. Reproduction studies conducted in pregnant rats and rabbits at oral doses up to 2.3 mg-base/kg/day, or 2 (rat) and 4 (rabbit) times the maximum recommended human dose (MRHD) of 12 mg/day on a mg/m2 basis, revealed no evidence of teratogenicity. Studies in pregnant rats showed slightly decreased fetal/pup weight at doses that were below the MRHD but usually associated with some maternal toxicity. Because animal reproduction studies are not always predictive of human response, this drug should be used during pregnancy only if clearly needed.

8.3 Nursing Mothers

Rivastigmine and its metabolites are excreted in rat milk following oral administration of rivastigmine; levels of rivastigmine plus metabolites in rat milk are approximately 2 times that in maternal plasma. It is not known whether rivastigmine is excreted in human milk. Because many drugs are excreted in human milk and because of the potential for serious adverse reactions in nursing infants from rivastigmine tartrate, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.

8.4 Pediatric Use

Safety and effectiveness in pediatric patients have not been established and therefore the use of rivastigmine in children and adolescents (below 18 years of age) is not recommended.

8.5 Geriatric Use

Of the total number of subjects in clinical studies of rivastigmine tartrate, 86 percent were 65 years and older while 46 percent were 75 years and older. No overall differences in safety or effectiveness were observed between these subjects and younger subjects, and other reported clinical experience has not identified differences in responses between the elderly and younger patients, but greater sensitivity of some older individuals cannot be ruled out.

8.6 Renal Impairment

In patients with moderate to severe renal impairment (glomerular filtration rate [GFR] <50 mL/min), clearance of oral rivastigmine was reduced [see Clinical Pharmacology (12.3)]. Accordingly, such patients may be able to only tolerate lower doses.

8.7 Hepatic Impairment

In patients with mild or moderate hepatic impairment (Child-Pugh score 5 to 9), clearance of oral rivastigmine was reduced [see Clinical Pharmacology (12.3)]. Accordingly, such patients may be able to only tolerate lower doses. No data are available on the use of rivastigmine in patients with severe hepatic impairment.

8.8 Low or High Body Weight

Because rivastigmine blood levels vary with weight, careful titration and monitoring should be performed in patients with low or high body weights. Compared to a patient with a body weight of 65 kg, the rivastigmine steady-state concentrations in a patient with a body weight of 35 kg would be approximately doubled, while for a patient with a body weight of 100 kg the concentrations would be approximately halved. In patients with low body weight (<50 kg), monitor closely for toxicities (e.g., excessive nausea, vomiting), and consider reducing the dose of Rivastigmine tartrate capsules if such toxicities develop.

12.1 Mechanism of Action

Although the precise mechanism of action of rivastigmine is unknown, it is thought 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. Therefore, the effect of rivastigmine may lessen as the disease process advances and fewer cholinergic neurons remain functionally intact. There is no evidence that rivastigmine alters the course of the underlying dementing process.

12.2 Pharmacodynamics

After a 6-mg dose of rivastigmine, anticholinesterase activity is present in cerebrospinal fluid (CSF) for about 10 hours, with a maximum inhibition of about 60% 5 hours after dosing.

In vitro and in vivo studies demonstrate that the inhibition of cholinesterase by rivastigmine is not affected by the concomitant administration of memantine, an N-methyl-D-aspartate receptor antagonist.

12.3 Pharmacokinetics

Rivastigmine shows linear pharmacokinetics up to 3 mg twice a day but is nonlinear at higher doses. Doubling the dose from 3 mg to 6 mg twice a day results in a 3-fold increase in AUC. The elimination half-life is about 1.5 hours, with most elimination as metabolites via the urine.

Absorption  

Rivastigmine is rapidly and completely absorbed. Peak plasma concentrations are reached in approximately 1 hour. Absolute bioavailability after a 3-mg dose is about 36%. Administration of rivastigmine tartrate with food delays absorption (tmax) by 90 minutes lowers Cmax by approximately 30% and increases AUC by approximately 30%.

Distribution  

Rivastigmine is weakly bound to plasma proteins (approximately 40%) over the therapeutic range. It readily crosses the blood-brain barrier, reaching CSF peak concentrations in 1.4 to 2.6 hours. It has an apparent volume of distribution in the range of 1.8 to 2.7 L/kg.

Metabolism  

Rivastigmine is rapidly and extensively metabolized, primarily via cholinesterase-mediated hydrolysis to the decarbamylated metabolite. Based on evidence from in vitro and animal studies, the major cytochrome P450 isozymes are minimally involved in rivastigmine metabolism. Consistent with these observations is the finding that no drug interactions related to cytochrome P450 have been observed in humans [see Drug Interactions (7.1)].

Elimination  

The major pathway of elimination is via the kidneys. Following administration of 14C-rivastigmine to 6 healthy volunteers, total recovery of radioactivity over 120 hours was 97% in urine and 0.4% in feces. No parent drug was detected in urine. The sulfate conjugate of the decarbamylated metabolite is the major component excreted in urine and represents 40% of the dose. Mean oral clearance of rivastigmine is 1.8 ± 0.6 L/min after 6 mg twice a day.

Renal Impairment  

Following a single 3-mg dose, mean oral clearance of rivastigmine is 64% lower in moderately impaired renal patients (n=8, GFR=10 to 50 mL/min) than in healthy subjects (n=10, GFR≥60 mL/min); Cl/F=1.7 L/min and 4.8 L/min, respectively. In patients with severe renal impairment (n=8, GFR <10 mL/min), mean oral clearance of rivastigmine is 43% higher than in healthy subjects (n=10, GFR ≥60 mL/min); Cl/F=6.9 L/min and 4.8 L/min, respectively. For unexplained reasons, the severely impaired renal patients had a higher clearance of rivastigmine than moderately impaired patients. Despite this finding, such patients may be able to only tolerate lower doses.

Hepatic Impairment  

Following a single 3-mg dose, mean oral clearance of rivastigmine was 60% lower in hepatically impaired patients (n=10, biopsy proven) than in healthy subjects (n=10). After multiple 6-mg twice a day oral dosing, the mean clearance of rivastigmine was 65% lower in mild (n=7, Child-Pugh score 5 to 6) and moderate (n=3, Child-Pugh score 7 to 9) hepatically impaired patients (biopsy proven, liver cirrhosis) than in healthy subjects (n=10). Accordingly, such patients may be able to only tolerate lower doses.

Body Weight  

A relationship between drug exposure at steady-state (rivastigmine and metabolite NAP226-90) and body weight was observed in Alzheimer’s dementia patients. Rivastigmine exposure is higher in subjects with low body weight. Compared to a patient with a body weight of 65 kg, the rivastigmine steady-state concentrations in a patient with a body weight of 35 kg would be approximately doubled, while for a patient with a body weight of 100 kg the concentrations would be approximately halved.

Age  

Following a single 2.5-mg oral dose to elderly volunteers (60 years and older, n=24) and younger volunteers (n=24), mean oral clearance of rivastigmine was 30% lower in elderly (7 L/min) than in younger subjects (10 L/min).

Gender or Race  

Population pharmacokinetic analysis of oral rivastigmine indicated that neither gender (n=277 males and 348 females) nor race (n=575 Caucasian, 34 Black, 4 Asian, and 12 Other) affected clearance of the drug.

Smoking  

Population pharmacokinetic analysis showed that nicotine use increased the oral clearance of rivastigmine by 23% (n=75 smokers and 549 nonsmokers).

Drug Interaction Studies

Effect of Rivastigmine on the Metabolism of Other Drugs  

Rivastigmine is primarily metabolized through hydrolysis by esterases. Minimal metabolism occurs via the major cytochrome P450 isoenzymes. Based on in vitro studies, no pharmacokinetic drug interactions with drugs metabolized by the following isoenzyme systems are expected: CYP1A2, CYP2D6, CYP3A4/5, CYP2E1, CYP2C9, CYP2C8, CYP2C19, or CYP2B6.

No pharmacokinetic interaction was observed between rivastigmine taken orally and digoxin, warfarin, diazepam or fluoxetine in studies in healthy volunteers. The increase in prothrombin time induced by warfarin is not affected by administration of rivastigmine.

Effect of Other Drugs on the Metabolism of Rivastigmine  

Drugs that induce or inhibit CYP450 metabolism are not expected to alter the metabolism of rivastigmine.

Population pharmacokinetic analysis with a database of 625 patients showed that the pharmacokinetics of rivastigmine taken orally were not influenced by commonly prescribed medications such as antacids (n=77), antihypertensives (n=72), ß-blockers (n=42), calcium channel blockers (n=75), antidiabetics (n=21), NSAIDs (n=79), estrogens (n=70), salicylate analgesics (n=177), antianginals (n=35) and antihistamines (n=15).

13.1 Carcinogenesis & Mutagenesis & Impairment Of Fertility

Carcinogenesis  

In oral carcinogenicity studies conducted at doses up to 1.1 mg-base/kg/day in rats and 1.6 mg-base/kg/day in mice, rivastigmine was not carcinogenic. These doses are less than the maximum recommended human dose (MRHD) of 12 mg/day on a mg/m2 basis.

Mutagenesis  

Rivastigmine was clastogenic in in vitro chromosomal aberration assays in mammalian cells in the presence, but not the absence, of metabolic activation. Rivastigmine was negative in an in vitro bacterial reverse mutation (Ames) assay, an in vitro HGPRT assay, and in an in vivo mouse micronucleus test.

Impairment of Fertility  

Rivastigmine had no effect on fertility or reproductive performance in rats at oral doses up to 1.1 mg-base/kg/day, a dose less than the MRHD on a mg/m2 basis.