Rivastigmine

INDICATIONS AND USAGE Rivastigmine transdermal system is an acetylcholinesterase inhibitor indicated for treatment of: Mild, moderate, and severe dementia of the Alzheimer’s type (AD). (1.1) Mild-to-moderate dementia associated with Parkinson’s disease (PD). (1.2) 1.1 Alzheimer’s Disease Rivastigmine transdermal system is indicated for the treatment of dementia of the Alzheimer’s type (AD). Efficacy has been demonstrated in patients with mild, moderate, and severe Alzheimer’s disease. 1.2 Parkinson’s Disease Dementia Rivastigmine transdermal system is indicated for the treatment of mild-to-moderate dementia associated with Parkinson’s disease (PDD). 1.1 Alzheimer’s Disease Rivastigmine transdermal system is indicated for the treatment of dementia of the Alzheimer’s type (AD). Efficacy has been demonstrated in patients with mild, moderate, and severe Alzheimer’s disease. 1.2 Parkinson’s Disease Dementia Rivastigmine transdermal system is indicated for the treatment of mild-to-moderate dementia associated with Parkinson’s disease (PDD).

DOSAGE AND ADMINISTRATION Apply patch on intact skin for a 24-hour period; replace with a new patch every 24 hours. (2.1, 2.4) Initial Dose: Initiate treatment with 4.6 mg/24 hours rivastigmine transdermal system. (2.1) Dose Titration: After a minimum of 4 weeks, if tolerated, increase dose to 9.5 mg/24 hours, which is the minimum effective dose. Following a minimum additional 4 weeks, may increase dosage to maximum dosage of 13.3 mg/24 hours. (2.1) Mild-to-Moderate Alzheimer’s Disease and Parkinson’s Disease Dementia: Rivastigmine transdermal system 9.5 mg/24 hours or 13.3 mg/24 hours once daily. (2.1) Severe Alzheimer’s Disease: Rivastigmine transdermal system 13.3 mg/24 hours once daily. (2.1) For treatment interruption longer than 3 days, retitrate dosage starting at 4.6 mg per 24 hours. (2.1) Consider dose adjustments in patients with (2.2) : Mild-to-moderate hepatic impairment (8.6) Low (less than 50 kg) body weight (8.7) 2.1 Recommended Dosing Initial Dose Initiate treatment with one 4.6 mg/24 hours rivastigmine transdermal system applied to the skin once daily [see Dosage and Administration (2.4) ] . Dose Titration Increase the dose only after a minimum of 4 weeks at the previous dose, and only if the previous dose has been tolerated. For mild-to-moderate AD and PDD patients, continue the effective dose of 9.5 mg/24 hours for as long as therapeutic benefit persists. Patients can then be increased to the maximum effective dose of 13.3 mg/24 hours dose. For patients with severe AD, 13.3 mg/24 hours is the effective dose. Doses higher than 13.3 mg/24 hours confer no appreciable additional benefit, and are associated with an increase in the incidence of adverse reactions [see Warnings and Precautions (5.2) , Adverse Reactions (6.1) ] . Mild-to-Moderate Alzheimer’s Disease and Mild-to-Moderate Parkinson’s Disease Dementia The effective dosage of rivastigmine transdermal system is 9.5 mg/24 hours or 13.3 mg/24 hours administered once per day; replace with a new patch every 24 hours. Severe Alzheimer’s Disease The effective dosage of rivastigmine transdermal system in patients with severe Alzheimer’s disease is 13.3 mg/24 hours administered once per day; replace with a new patch every 24 hours. Interruption of Treatment If dosing is interrupted for 3 days or fewer, restart treatment with the same or lower strength rivastigmine transdermal system. If dosing is interrupted for more than 3 days, restart treatment with the 4.6 mg/24 hours rivastigmine transdermal system and titrate as described above. 2.2 Dosing in Specific Populations Dosing Modifications in Patients with Hepatic Impairment Consider using the 4.6 mg/24 hours rivastigmine transdermal system as both the initial and maintenance dose in patients with mild (Child-Pugh score 5 to 6) to moderate (Child-Pugh score 7 to 9) hepatic impairment [see Use in Specific Populations (8.6) , Clinical Pharmacology (12.3) ] . Dosing Modifications in Patients with Low Body Weight Carefully titrate and monitor patients with low body weight (less than 50 kg) for toxicities (e.g., excessive nausea, vomiting), and consider reducing the maintenance dose to the 4.6 mg/24 hours rivastigmine transdermal system if such toxicities develop. 2.3 Switching to Rivastigmine Transdermal System from Rivastigmine Tartrate Capsules or Rivastigmine Tartrate Oral Solution Patients treated with rivastigmine tartrate capsules or oral solution may be switched to rivastigmine transdermal system as follows: A patient who is on a total daily dose of less than 6 mg of oral rivastigmine can be switched to the 4.6 mg/24 hours rivastigmine transdermal system. A patient who is on a total daily dose of 6 mg to 12 mg of oral rivastigmine can be switched to the 9.5 mg/24 hours rivastigmine transdermal system. Instruct patients or caregivers to apply the first patch on the day following the last oral dose. 2.4 Important Administration Instructions Rivastigmine transdermal system is a patch for transdermal use on intact skin. (a) Do not use the patch if the pouch seal is broken or the patch is cut, damaged, or changed in any way. (b) Apply the rivastigmine transdermal system once a day. Press down firmly for 30 seconds until the edges stick well when applying to clean, dry, hairless, intact healthy skin in a place that will not be rubbed against by tight clothing. Use the upper or lower back as the site of application because the patch is less likely to be removed by the patient. If sites on the back are not accessible, apply the patch to the upper arm or chest. Do not apply to a skin area where cream, lotion, or powder has recently been applied. (c) Do not apply to skin that is red, irritated, or cut. (d) Replace the rivastigmine transdermal system with a new patch every 24 hours. Instruct patients to only wear 1 patch at a time (remove the previous day’s patch before applying a new patch) [see Warnings and Precautions (5.1) , Overdosage (10) ] . If a patch falls off or if a dose is missed, apply a new patch immediately, and then replace this patch the following day at the usual application time. (e) Change the site of patch application daily to minimize potential irritation, although a new patch can be applied to the same general anatomic site (e.g., another spot on the upper back) on consecutive days. Do not apply a new patch to the same location for at least 14 days. (f) May wear the patch during bathing and in hot weather. Avoid long exposure to external heat sources (excessive sunlight, saunas, solariums). (g) Place used patches in the previously saved pouch and discard in the trash, away from pets or children. (h) Wash hands with soap and water after removing the patch. In case of contact with eyes or if the eyes become red after handling the patch, rinse immediately with plenty of water, and seek medical advice if symptoms do not resolve. 2.1 Recommended Dosing Initial Dose Initiate treatment with one 4.6 mg/24 hours rivastigmine transdermal system applied to the skin once daily [see Dosage and Administration (2.4) ] . Dose Titration Increase the dose only after a minimum of 4 weeks at the previous dose, and only if the previous dose has been tolerated. For mild-to-moderate AD and PDD patients, continue the effective dose of 9.5 mg/24 hours for as long as therapeutic benefit persists. Patients can then be increased to the maximum effective dose of 13.3 mg/24 hours dose. For patients with severe AD, 13.3 mg/24 hours is the effective dose. Doses higher than 13.3 mg/24 hours confer no appreciable additional benefit, and are associated with an increase in the incidence of adverse reactions [see Warnings and Precautions (5.2) , Adverse Reactions (6.1) ] . Mild-to-Moderate Alzheimer’s Disease and Mild-to-Moderate Parkinson’s Disease Dementia The effective dosage of rivastigmine transdermal system is 9.5 mg/24 hours or 13.3 mg/24 hours administered once per day; replace with a new patch every 24 hours. Severe Alzheimer’s Disease The effective dosage of rivastigmine transdermal system in patients with severe Alzheimer’s disease is 13.3 mg/24 hours administered once per day; replace with a new patch every 24 hours. Interruption of Treatment If dosing is interrupted for 3 days or fewer, restart treatment with the same or lower strength rivastigmine transdermal system. If dosing is interrupted for more than 3 days, restart treatment with the 4.6 mg/24 hours rivastigmine transdermal system and titrate as described above. 2.2 Dosing in Specific Populations Dosing Modifications in Patients with Hepatic Impairment Consider using the 4.6 mg/24 hours rivastigmine transdermal system as both the initial and maintenance dose in patients with mild (Child-Pugh score 5 to 6) to moderate (Child-Pugh score 7 to 9) hepatic impairment [see Use in Specific Populations (8.6) , Clinical Pharmacology (12.3) ] . Dosing Modifications in Patients with Low Body Weight Carefully titrate and monitor patients with low body weight (less than 50 kg) for toxicities (e.g., e

WARNINGS AND PRECAUTIONS Hospitalization and, rarely, death have been reported due to application of multiple patches at same time. Ensure patients or caregivers receive instruction on proper dosing and administration. ( 5.1 ) Gastrointestinal Adverse Reactions: May include significant nausea, vomiting, diarrhea, anorexia/decreased appetite, and weight loss, and may necessitate treatment interruption. Dehydration may result from prolonged vomiting or diarrhea and can be associated with serious outcomes. ( 5.2 ) Application-site reactions may occur with the patch form of rivastigmine. Discontinue treatment if application-site reactions spread beyond the patch size, if there is evidence of a more intense local reaction (e.g., increasing erythema, edema, papules, vesicles), and if symptoms do not significantly improve within 48 hours after patch removal. ( 5.3 ) 5.1 Medication Errors Resulting in Overdose Medication errors with rivastigmine transdermal system have resulted in serious adverse reactions; some cases have required hospitalization, and rarely, led to death. The majority of medication errors have involved not removing the old patch when putting on a new one and the use of multiple patches at one time. Instruct patients and their caregivers on important administration instructions for rivastigmine transdermal system [see Dosage and Administration (2.4) ] . 5.2 Gastrointestinal Adverse Reactions Rivastigmine transdermal system 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, initiate treatment with rivastigmine transdermal system at a dose of 4.6 mg/24 hours, and titrate to a dose of 9.5 mg/24 hours, and then to a dose of 13.3 mg/24 hours, if appropriate [see Dosage and Administration (2.1) ] . If treatment is interrupted for more than 3 days because of intolerance, reinitiate rivastigmine transdermal system with the 4.6 mg/24 hours dose to reduce the possibility of severe vomiting and its potentially serious sequelae. A postmarketing report described a case of severe vomiting with esophageal rupture following inappropriate reinitiation of treatment of an oral formulation of rivastigmine without retitration 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. 5.3 Skin Reactions Skin application-site reactions may occur with rivastigmine transdermal system. These reactions are not in themselves an indication of sensitization. However, use of rivastigmine patch may lead to allergic contact dermatitis. Allergic contact dermatitis should be suspected if application-site reactions spread beyond the patch size, if there is evidence of a more intense local reaction (e.g., increasing erythema, edema, papules, vesicles), and if symptoms do not significantly improve within 48 hours after patch removal. In these cases, treatment should be discontinued [see Contraindications (4) ] . In patients who develop application-site reactions to rivastigmine transdermal system, suggestive of allergic contact dermatitis 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. There have been isolated postmarketing reports of patients experiencing disseminated allergic dermatitis when administered rivastigmine irrespective of the route of administration (oral or transdermal). In these cases, treatment should be discontinued [see Contraindications (4) ] . Patients and caregivers should be instructed accordingly. 5.4 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 increase gastric acid secretion due to increased cholinergic activity. Monitor patients using rivastigmine transdermal system 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 the rivastigmine transdermal system 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. 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 transdermal system should be used with care in patients with a history of asthma or obstructive pulmonary disease. 5.5 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 transdermal system, routinely evaluate the patient’s ability to continue driving or operating machinery. 5.1 Medication Errors Resulting in Overdose Medication errors with rivastigmine transdermal system have resulted in serious adverse reactions; some cases have required hospitalization, and rarely, led to death. The majority of medication errors have involved not removing the old patch when putting on a new one and the use of multiple patches at one time. Instruct patients and their caregivers on important administration instructions for rivastigmine transdermal system [see Dosage and Administration (2.4) ] . 5.2 Gastrointestinal Adverse Reactions Rivastigmine transdermal system 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, initiate treatment with rivastigmine transdermal system at a dose of 4.6 mg/24 hours, and titrate to a dose of 9.5 mg/24 hours, and then to a dose of 13.3 mg/24 hours, if appropriate [see Dosage and Administration (2.1) ] . If treatment is interrupted for more than 3 days because of intolerance, reinitiate rivastigmine transdermal system with the 4.6 mg/24 hours dose to reduc

CONTRAINDICATIONS Rivastigmine tartrate capsules are contraindicated in patients with: • known hypersensitivity to rivastigmine, other carbamate derivatives or other components of the formulation [ see Description (11) ]. • a previous history of application site reaction with rivastigmine transdermal patch suggestive of allergic contact dermatitis, in the absence of negative allergy testing [ see Warnings and Precautions (5.2) ]. Isolated cases of generalized skin reactions have been described in postmarketing experience [ see Adverse Reactions (6.2) ]. • Known hypersensitivity to rivastigmine, other carbamate derivatives or other components of the formulation. ( 4 ) • History of application site reaction with rivastigmine transdermal patch suggestive of allergic contact dermatitis, in the absence of negative allergy testing. ( 4 , 5.2 )

DRUG INTERACTIONS Concomitant use with metoclopramide, beta-blockers, or cholinomimetics and anticholinergic medications is not recommended. ( 7.1, 7.2, 7.3 ) 7.1 Metoclopramide Due to the risk of additive extra-pyramidal adverse reactions, the concomitant use of metoclopramide and rivastigmine transdermal system is not recommended. 7.2 Cholinomimetic and Anticholinergic Medications Rivastigmine transdermal system may increase the cholinergic effects of other cholinomimetic medications and may also interfere with the activity of anticholinergic medications (e.g., oxybutynin, tolterodine). Concomitant use of rivastigmine transdermal system with medications having these pharmacologic effects is not recommended unless deemed clinically necessary [see Warnings and Precautions (5.5) ] . 7.3 Beta-Blockers Additive bradycardic effects resulting in syncope may occur when rivastigmine is used concomitantly with beta-blockers, especially cardioselective beta-blockers (including atenolol). Concomitant use is not recommended when signs of bradycardia, including syncope are present. 7.1 Metoclopramide Due to the risk of additive extra-pyramidal adverse reactions, the concomitant use of metoclopramide and rivastigmine transdermal system is not recommended.

ADVERSE REACTIONS The following adverse reactions are described below and elsewhere in the labeling: · Gastrointestinal Adverse Reactions [see Warnings and Precautions (5.1)] · Allergic Dermatitis [see Warnings and Precautions (5.2)] · Other Adverse Reactions from Increased Cholinergic Activity [see Warnings and Precautions (5.3)] Most common adverse reactions (greater than 5% and 2 times greater than placebo): nausea, vomiting, anorexia, dyspepsia, and asthenia (6.1) To report SUSPECTED ADVERSE REACTIONS, contact Alembic Pharmaceuticals Limited at 1-866-210-9797 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 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 Common 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 Study Phase Titration Maintenance Overall Rivastigmine Tartrate Placebo Rivastigmine Tartrate Placebo Rivastigmine Tartrate Placebo ≥6 to 12 mg/day ≥6 to 12 mg/day ≥6 to 12 mg/day (n=1,189) (n=868) (n=987) (n=788) (n=1,189) (n=868) Event/% Discontinuing Nausea 8 <1 1 <1 8 1 Vomiting 4 <1 1 <1 5 <1 Anorexia 2 0 1 <1 3 <1 Dizziness 2 <1 1 <1 2 <1 Adverse Reactions Observed at an Incidence of at Least 2% Table 2 lists adverse reactions that occurred 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. 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 reactions 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 Greater Than or Equal to 2% and at a Rate Greater than Placebo in Clinical Trials Body System/Adverse Reaction Rivastigmine Tartrate (6 to 12 m g/day) (n=1,189) Placebo (n=868) Percent of Patients with any Adverse Event 92 79 Autonomic Nervous System Increased Sweating 4 1 Syncope 3 2 Body as a Whole Fatigue 9 5 Asthenia 6 2 Malaise 5 2 Decreased Weight ** 3 <1 Cardiovascular Disorders, General Hypertension 3 2 Central and Peripheral Nervous System Dizziness 21 11 Headache 17 12 Somnolence 5 3 Tremor 4 1 Gastrointestinal System Nausea* 47 12 Vomiting* 31 6 Diarrhea 19 11 Anorexia*** 17 3 Abdominal Pain 13 6 Dyspepsia 9 4 Psychiatric Disorders Insomnia 9 7 Confusion 8 7 Depression 6 4 Anxiety 5 3 Hallucination 4 3 Aggressive Reaction 3 2 Resistance Mechanism Disorders Urinary Tract Infection 7 6 * 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 Common 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, 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% for patients receiving 3 mg to 12 mg per day compared to 11% for patients on placebo during the 24-week study. The most frequent adverse reactions 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% placebo). Adverse Reactions Observed at an Incidence of at Least 2% Table 3 lists adverse reactions that occurred 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

CLINICAL PHARMACOLOGY 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 (t max ) by 90 minutes lowers C max 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. Elimination The major pathway of elimination is via the kidneys. Following administration of 14 C-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. 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 and 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. 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. 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. 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). Smoking Following oral rivastigmine administration (up to 12 mg/day) with nicotine use, population pharmacokinetic analysis showed increased 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), beta-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).