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Exelon: Drug for Alzheimer’s Disease

Brand Name Drug: Exelon
Active Ingredient Drug: rivastigmine tartrate
Indication: Treatment of mild to moderate Alzheimer’s disease
Company Name: Novartis Pharmaceuticals Corporation
Availability: Approved by the FDA on April 24, 2000

Introduction

ExelonSome 4 million Americans are afflicted with Alzheimer’s disease, a number that is expected to grow as the population ages. Tacrine (Cognex) and donepezil (Aricept) are prescription drugs currently available to treat symptoms or slow progression of the disease. A new drug was recently approved for the treatment of mild to moderate Alzheimer’s disease: Exelon (rivastigmine tartrate), manufactured by Novartis Pharmaceuticals Corporation.

Exelon is a cholinesterase inhibitor that has been proven effective in multiple phase III trials in the key domains used to assess the disease – global functioning (including activities of daily living and behavior) and cognition. The dosage of Exelon (rivastigmine tartrate) that was shown to be most effective was 6-12 mg/day, given as divided doses twice daily.

Exelon has been cleared for marketing in nearly 70 countries worldwide, including all 15 member states of the European Union, Switzerland, New Zealand, Australia, Canada, and Mexico.

How It Works

While the precise mechanism of Exelon’s function is unknown, it is postulated to exert its therapeutic effect by enhancing cholinergic function. This is achieved by increasing the concentration of acetylcholine through reversible inhibition of its hydrolysis by cholinesterase. If this proposed mechanism is correct, Exelon’s effect may lessen as the disease progresses and fewer cholinergic neurons remain functionally intact. There is no evidence that Exelon alters the course of the underlying dementing process.

Exelon (rivastigmine tartrate): Clinical Study Results

Marketing clearance for Exelon was based on results of the largest phase III clinical program of an Alzheimer’s disease medication to date, involving more than 3,900 patients worldwide. Overall, nearly 5,300 patients have received Exelon in clinical trials. More than 2,100 patients have been treated with Exelon for one year, 1,250 have been treated for two years, and 168 have been treated for over three years. The six-month clinical trials with Exelon involved patients with mild to moderate Alzheimer’s disease, 94% of whom also suffered from a variety of medical illnesses common in the elderly, including hypertension, type 2 diabetes, and arthritis. Virtually all patients in the studies used concomitant medications, allowing researchers to assess the efficacy and safety of Exelon (rivastigmine tartrate) in a patient population similar to a “real world” population.

In clinical trials, on average, patients treated with Exelon were considered clinically improved compared to those on placebo at the end of six months. During the clinical trials, patients treated with 6-12 mg/day Exelon were far more likely to experience substantial cognitive improvement and far less likely to show substantial decline than were patients given placebo. Moreover, at 26 weeks, 81% of those given 6-12 mg/day Exelon (rivastigmine tartrate) had greater improvement/less worsening in cognitive function than did the average placebo-treated patient. Patients treated with Exelon demonstrated significant improvement compared to placebo in areas such as average total word recall and recognition, orientation, and ability to speak.

In addition, patients treated with 6-12 mg/day Exelon demonstrated a significant improvement in global functioning as measured by the CIBIC-Plus (a structured instrument based on a comprehensive evaluation of patient cognition, behavior and functioning, including assessment of activities of daily living). Fifty percent more patients treated with Exelon were rated improved at week 26 on the CIBIC-Plus than patients given placebo. During the clinical trials, patients give Exelon demonstrated fewer delusions than those given placebo and engaged in less purposeless activity (e.g., engaging in an activity for no particular reason, such as repeatedly opening and closing a door). In clinical trials, higher therapeutic doses of Exelon (rivastigmine tartrate) were associated with greater benefit.

What the Patient Should Know

The most common side effects seen with Exelon include nausea, vomiting, anorexia, dyspepsia, and asthenia, which were usually transient and generally mild to moderate in severity. The gastrointestinal adverse reactions associated with the drug are considered significant. In general, adverse reactions were less frequent later in the course of treatment. Exelon (rivastigmine tartrate) should not be used in patients with known hypersensitivity to rivastigmine, other carbamate derivatives, or other components of the formulation.

In controlled clinical trials, 26% of women and 18% of men in the high-dose group experienced weight loss of equal or greater than 7% of their baseline body weight, compared to 6% and 4% of patients given placebo respectively. In most cases, weight loss attenuates upon dose reduction or interruption of treatment. Weight loss also attenuated in patients with long-term treatment.

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