Donepezil

12.1 Mechanism of Action Current theories on the pathogenesis of the cognitive signs and symptoms of Alzheimer's disease attribute some of them to a deficiency of cholinergic neurotransmission. Donepezil hydrochloride is postulated 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 acetylcholinesterase. There is no evidence that donepezil alters the course of the underlying dementing process.

1 INDICATIONS AND USAGE Donepezil hydrochloride tablet is an acetylcholinesterase inhibitor indicated for the treatment of dementia of the Alzheimer's type. Efficacy has been demonstrated in patients with mild, moderate, and severe Alzheimer's Disease ( 1 ). Donepezil hydrochloride tablet is indicated for the treatment of dementia of the Alzheimer's type. Efficacy has been demonstrated in patients with mild, moderate, and severe Alzheimer's disease.

2 DOSAGE AND ADMINISTRATION Mild to Moderate Alzheimer's Disease: 5 mg to 10 mg once daily ( 2.1 ) Moderate to Severe Alzheimer's Disease: 10 mg to 23 mg once daily ( 2.2 ) 2.1 Dosing in Mild to Moderate Alzheimer’s Disease The recommended starting dosage of donepezil hydrochloride tablet is 5 mg administered once per day in the evening, just prior to retiring. The maximum recommended dosage of donepezil hydrochloride tablets in patients with mild to moderate Alzheimer's disease is 10 mg per day. A dose of 10 mg should not be administered until patients have been on a daily dose of 5 mg for 4 to 6 weeks. 2.2 Dosing in Moderate to Severe Alzheimer’s Disease The recommended starting dosage of donepezil hydrochloride tablet is 5 mg administered once per day in the evening, just prior to retiring. The maximum recommended dosage of donepezil hydrochloride tablets in patients with moderate to severe Alzheimer's disease is 23 mg per day. A dose of 10 mg should not be administered until patients have been on a daily dose of 5 mg for 4 to 6 weeks. A dose of 23 mg per day should not be administered until patients have been on a daily dose of 10 mg for at least 3 months. 2.3 Administration Information Donepezil hydrochloride tablets should be taken in the evening, just prior to retiring. Donepezil hydrochloride tablets can be taken with or without food. The donepezil hydrochloride 23 mg tablet should not be split, crushed, or chewed.

6 ADVERSE REACTIONS Most common adverse reactions in clinical studies of donepezil hydrochloride are nausea, diarrhea, insomnia, vomiting, muscle cramps, fatigue, and anorexia ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Lupin Pharmaceuticals, Inc. at 1-800-399-2561 or FDA at 1-800-FDA-1088 or www.fda.gov/ medwatch . The following serious adverse reactions are described below and elsewhere in the labeling: Cardiovascular Conditions [ see Warnings and Precautions ( 5.2 ) ]. Nausea and Vomiting [ see Warnings and Precautions ( 5.3 ) ]. Peptic Ulcer Disease and GI Bleeding [ see Warnings and Precautions ( 5.4 ) ]. Weight Loss [ see Warnings and Precautions ( 5.5 ) ]. Genitourinary Conditions [ see Warnings and Precautions ( 5.6 ) ]. Neurological Conditions: Seizures [ see Warnings and Precautions ( 5.7 ) ]. Pulmonary Conditions [ see Warnings and Precautions ( 5.8 ) ]. 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. Donepezil hydrochloride has been administered to over 1,700 individuals during clinical trials worldwide. Approximately 1200 of these patients have been treated for at least 3 months and more than 1,000 patients have been treated for at least 6 months. Controlled and uncontrolled trials in the United States included approximately 900 patients. In regards to the highest dose of 10 mg/day, this population includes 650 patients treated for 3 months, 475 patients treated for 6 months, and 116 patients treated for over 1 year. The range of patient exposure is from 1 to 1,214 days. Mild to Moderate Alzheimer's Disease Adverse Reactions Leading to Discontinuation: The rates of discontinuation from controlled clinical trials of donepezil hydrochloride due to adverse reactions for the donepezil hydrochloride 5 mg/day treatment groups were comparable to those of placebo treatment groups at approximately 5%. The rate of discontinuation of patients who received 7-day escalations from 5 mg/day to 10 mg/day was higher at 13%. The most common adverse reactions leading to discontinuation, defined as those occurring in at least 2% of patients and at twice or more the incidence seen in placebo patients, are shown in Table 1. Table 1 . Most Common Adverse Reactions Leading to Discontinuation in Patients with Mild to Moderate Alzheimer’s Disease Adverse Reaction Placebo ( n = 355 ) % 5 mg / day Donepezil Hydrochloride ( n = 350 ) % 10 mg / day Donepezil Hydrochloride ( n = 315 ) % Nausea 1 1 3 Diarrhea 0 <1 3 Vomiting <1 <1 2 Most Common Adverse Reactions: The most common adverse reactions, defined as those occurring at a frequency of at least 5% in patients receiving 10 mg/day and twice the placebo rate, are largely predicted by donepezil hydrochloride's cholinomimetic effects. These include nausea, diarrhea, insomnia, vomiting, muscle cramp, fatigue, and anorexia. These adverse reactions were often transient, resolving during continued donepezil hydrochloride treatment without the need for dose modification. There is evidence to suggest that the frequency of these common adverse reactions may be affected by the rate of titration. An open-label study was conducted with 269 patients who received placebo in the 15- and 30-week studies. These patients were titrated to a dose of10 mg/day over a 6-week period. The rates of common adverse reactions were lower than those seen in patients titrated to 10 mg/day over one week in the controlled clinical trials and were comparable to those seen in patients on 5 mg/day. See Table 2 for a comparison of the most common adverse reactions following one and six week titration regimens. Table 2 . Comparison of Rates of Adverse Reactions in Mild to Moderate Patients Titrated to 10 mg / day over 1 and 6 Weeks No titration One week titration Six week titration Adverse Reaction Placebo ( n = 315 ) % 5 mg / day ( n = 311 ) % 10 mg / day ( n = 315 ) % 10 mg / day ( n = 269 ) % Nausea 6 5 19 6 Diarrhea 5 8 15 9 Insomnia 6 6 14 6 Fatigue 3 4 8 3 Vomiting 3 3 8 5 Muscle cramps 2 6 8 3 Anorexia 2 3 7 3 Table 3 lists adverse reactions that occurred in at least 2% of patients in pooled placebo-controlled trials who received either donepezil hydrochloride 5 mg or 10 mg and for which the rate of occurrence was greater for patients treated with donepezil hydrochloride than with placebo. In general, adverse reactions occurred more frequently in female patients and with advancing age. Table 3 . Adverse Reactions in Pooled Placebo - Controlled Clinical Trials in Mild to Moderate Alzheimer’s Disease Adverse Reaction Placebo ( n = 355 ) % Donepezil Hydrochloride ( n = 747 ) % Percent of Patients with any Adverse Reaction 72 74 Nausea 6 11 Diarrhea 5 10 Headache 9 10 Insomnia 6 9 Pain, various locations 8 9 Dizziness 6 8 Accident 6 7 Muscle Cramps 2 6 Fa

7 DRUG INTERACTIONS Cholinesterase inhibitors have the potential to interfere with the activity of anticholinergic medications ( 7.1 ). A synergistic effect may be expected with concomitant administration of succinylcholine, similar neuromuscular blocking agents, or cholinergic agonists ( 7.2 ). 7.1 Use with Anticholinergics Because of their mechanism of action, cholinesterase inhibitors have the potential to interfere with the activity of anticholinergic medications. 7.2 Use with Cholinomimetics and Other Cholinesterase Inhibitors A synergistic effect may be expected when cholinesterase inhibitors are given concurrently with succinylcholine, similar neuromuscular blocking agents, or cholinergic agonists such as bethanechol.