Exelon Patch (rivastigmine) Drug Warnings & Precautions

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WARNINGS

Included as part of the PRECAUTIONS section.

PRECAUTIONS

Gastrointestinal Adverse Reactions

At higher than recommended doses Exelon Patch (rivastigmine transdermal system) use is associated with significant gastrointestinal adverse reactions, including nausea, vomiting, diarrhea, anorexia/decreased appetite and weight loss. For this reason, patients administered the Exelon Patch should always be started at a dose of 4.6 mg/24 hours and titrated to the maintenance dose of 9.5mg/24 hours. If treatment is interrupted for longer than several days, treatment should be reinitiated with the lowest daily dose (see DOSAGE AND ADMINISTRATION to reduce the possibility of severe vomiting and its potentially serious sequelae (e.g., there has been one post-marketing report of severe vomiting with esophageal rupture following inappropriate reinitiation of treatment with a 4.5-mg dose of an oral formulation after 8 weeks of treatment interruption).

At higher than recommended doses caregivers should be advised of the high incidence of nausea and vomiting associated with the use of the Exelon Patch along with the possibility of anorexia and weight loss. Caregivers should be encouraged to monitor for these adverse events and inform the physician if they occur. It is critical to inform caregivers that if therapy has been interrupted for more than several days, the next dose should not be administered until they have discussed this with the physician.

Nausea and Vomiting: In the controlled clinical trial, 7% of patients treated with the Exelon Patch 9.5mg/24 hours developed nausea, as compared to 23% of patients who received the Exelon capsule at doses up to 6 mg BID and 5% of those who received placebo. In the same clinical trial, 6% of patients treated with Exelon Patch 9.5mg/24 hours developed vomiting, as compared with 17% of patients who received the Exelon capsule at doses up to 6 mg BID and 3% of those who received placebo. The proportion of patients who discontinued treatment due to vomiting was 0% of the patients who received the Exelon Patch 9.5mg/24 hours as well as 2% of patients who received the Exelon capsule at doses up to 6 mg BID and 0% of those who received placebo. Vomiting was severe in 0% of patients who received the Exelon Patch 9.5mg/24 hours and 1% of patients who received the Exelon capsule at doses up to 6 mg BID and 0% of those who received placebo.

In the same clinical trial 21% of the patients treated with the higher dose of Exelon Patch 17.4 mg/24 hours developed nausea, 19% developed vomiting, and the proportion of these patients who discontinued treatment due to vomiting was 2%.Vomiting was severe in 1% of the patients treated with the Exelon Patch 17.4 mg/24.

Weight Loss: In the controlled clinical trial, the proportion of patients who had weight loss equal to or greater than 7% of their baseline weight was 8% of those treated with the Exelon Patch 9.5 mg/24 hours, 11% of patients who received the Exelon capsule at doses up to 6 mg BID and 6% of those who received placebo.

In the same clinical trial, 12% of those treated with 17.4mg/24 hours had weight loss equal to or greater than 7% of their baseline weight. It is not clear how much of the weight loss was associated with anorexia, nausea, vomiting, and the diarrhea associated with the drug.

Diarrhea: In the controlled clinical trial, 6% of the patients treated with the Exelon Patch 9.5 mg/24 hours developed diarrhea, as compared with 5% of patients who received the Exelon capsule at doses up to 6 mg BID, 10% of those treated with 17.4mg/24 hours and 3% of those who received placebo.

Anorexia/Decreased Appetite: In the controlled clinical trial, 3% of the patients treated with the Exelon Patch 9.5 mg/24 hours were recorded as developing decreased appetite or anorexia, as compared with 9% of patients who received the Exelon capsule at doses up to 6 mg BID, 9% of those treated with Exelon Patch 17.4mg/24 hours and 2% of those who received placebo.

Peptic Ulcers/Gastrointestinal Bleeding: Because of their pharmacological 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 at increased risk for developing ulcers, e.g., those with a history of ulcer disease or those receiving concurrent nonsteroidal antiinflammatory drugs (NSAIDs). Clinical studies of Exelon have shown no significant increase, relative to placebo, in the incidence of either peptic ulcer disease or gastrointestinal bleeding.

Anesthesia

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

Cardiovascular Conditions

Drugs that increase cholinergic activity may have vagotonic effects on heart rate (e.g., bradycardia). The potential for this action may be particularly important to patients with sick sinus syndrome or other supraventricular cardiac conduction conditions. In clinical trials, Exelon was not associated with any increased incidence of cardiovascular adverse events, heart rate or blood pressure changes, or ECG abnormalities.

Genitourinary Conditions

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

Neurological Conditions

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.

Extrapyramidal Symptoms: Like other cholinomimetics, 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 Exelon capsules.

Pulmonary Conditions

Like other drugs that increase cholinergic activity, Exelon should be used with care in patients with a history of asthma or obstructive pulmonary disease.

Effects on Ability to Drive and Use Machines

Dementia may cause gradual impairment of driving performance or compromise the ability to use machinery. The administration of rivastigmine may also result in adverse events that are detrimental to these functions. Thus, the ability to continue driving or operate machinery should be routinely evaluated by the treating physician.

Special Populations

Low Body Weight: Patients with body weight below 50 kg may experience more adverse events and may be more likely to discontinue due to adverse events. Particular caution should be exercised in titrating these patients above the recommended maintenance dose of the Exelon Patch 9.5 mg/24 hours.


NonClinical Toxicology

Carcinogenesis, Mutagenesis, Impairment of Fertility

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.

In a dermal carcinogenicity study conducted at doses up to 0.75 mg-base/kg/day in mice, rivastigmine was not carcinogenic. The mean rivastigmine plasma exposure (AUC) at this dose was 0.3-0.4 times that observed in Alzheimer's disease patients at the recommended clinical dose (one Exelon Patch 9.5 mg/24 hours).

Rivastigmine was clastogenic in two in vitro assays in the presence, but not the absence, of metabolic activation. It caused structural chromosomal aberrations in V79 Chinese hamster lung cells and both structural and numerical (polyploidy) chromosomal aberrations in human peripheral blood lymphocytes. Rivastigmine was not genotoxic in three in vitro assays: the Ames test, the unscheduled DNA synthesis (UDS) test in rat hepatocytes (a test for induction of DNA repair synthesis), and the HGPRT test in V79 Chinese hamster cells. Rivastigmine was not clastogenic in the in vivo mouse micronucleus test.

No fertility or reproduction studies have been conducted in animals treated with dermal rivastigmine. Rivastigmine had no effect on fertility or reproductive performance in rats at oral doses up to 1.1 mg-base/kg/day.


Use In Specific Populations

Pregnancy

Pregnancy Category B: There are no adequate or well-controlled studies in pregnant women. Because animal reproduction studies are not always predictive of human response, the Exelon Patch should be used during pregnancy only if the potential benefit outweighs the potential risk to the fetus.

No dermal reproduction studies in animals have been conducted. Oral reproduction studies conducted in pregnant rats at doses up to 2.3 mg-base/kg/day and in pregnant rabbits at doses up to 2.3 mg-base/kg/day revealed no evidence of teratogenicity. Studies in rats showed slightly decreased fetal/pup weights, usually at doses causing some maternal toxicity.


Nursing Mothers

Milk transfer studies in animals have not been conducted with dermal rivastigmine. In rats given rivastigmine orally, concentrations of rivastigmine plus metabolites were approximately two times higher in milk than in plasma. It is not known whether rivastigmine is excreted in human breast milk. Exelon Patch (rivastigmine transdermal system) has no indication for use in nursing mothers.


Pediatric Use

There are no adequate and well-controlled trials documenting the safety and efficacy of Exelon in any illness occurring in children.


Geriatric Use

Age had no impact on the exposure to rivastigmine in Alzheimer's disease patients treated with the Exelon Patch.


Hepatic Disease

No pharmacokinetic study was conducted with the Exelon Patch in subjects with 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 BID oral dosing, the mean clearance of rivastigmine was 65% lower in mild (n=7, Child-Pugh score 5-6) and moderate (n=3, Child-Pugh score 7-9) hepatically impaired patients (biopsy proven, liver cirrhosis) than in healthy subjects (n=10). Dosage adjustment is not necessary in hepatically impaired patients as the dose of drug is individually titrated to tolerability.


Renal Disease

No study was conducted with the Exelon Patch in subjects with renal impairment. Following a single 3-mg dose, mean oral clearance of rivastigmine is 64% lower in moderately impaired renal patients (n=8, GFR=10-50 mL/min) than in healthy subjects (n=10, GFR > /=60 mL/min); Cl/F=1.7 L/min (cv=45%) and 4.8 L/min (cv=80%), respectively. In severely impaired renal patients (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. However, dosage adjustment may not be necessary in renally impaired patients as the dose of the drug is individually titrated to tolerability.


Low Body Weight

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. This suggests special attention should be given to patients with very low body weight during up-titration (see DOSAGE AND ADMINISTRATION).


Gender and Race

No specific pharmacokinetic study was conducted to investigate the effect of gender and race on the disposition of Exelon, but a population pharmacokinetic analysis indicates that gender (n=277 males and 348 females) and race (n=575 White, 34 Black, 4 Asian, and 12 Other) did not affect the clearance of Exelon administered orally. Similar results were seen with analyses of pharmacokinetic data obtained after the administration of the Exelon Patch


Nicotine Use

Population pharmacokinetic analysis showed that nicotine use increases the oral clearance of rivastigmine by 23% (n=75 Smokers and 549 Nonsmokers). No dose adjustment is necessary as the dose of the drug is individually titrated to tolerability.