Results from the first head-to-head study between Aricept (donepezil hydrochloride) and Exelon (rivastigmine tartrate) showed that in this open-label study, Aricept was better tolerated than Exelon, in patients with mild to moderate Alzheimer’s disease. The findings were presented at a scientific conference held recently in Munich, Germany.
“Despite the often devastating nature of the disease, tolerability is still very important to patients with Alzheimer’s disease,” said David Wilkinson, MD, director of the Memory Assessment and Research Centre, Southampton, England, and an investigator in the study. “Patients tend to be elderly and often have other medical conditions that can make treating Alzheimer’s disease more complex. It is therefore important to treat patients with medications that are well tolerated and easy to use.”
The multinational, head-to-head, open-label study was designed to compare the tolerability and ease of use of Aricept to Exelon in 111 patients with mild to moderate Alzheimer’s disease.
Both medications appeared to do an equal job of improving cognition as reflected in the scores from cognitive skills tests. The two treatment groups had similar improvements from baseline scores in Alzheimer’s Disease Assessment Scale-cognitive subscale (ADAS-cog) scores throughout the 12-week treatment period. ADAS-cog is a clinically validated measure of cognitive function. Independent raters administered the tests and it was unknown to them which medication was being tested at the time.
There were however, significant differences in the side-effects experienced. According to the study, almost four times as many patients in the Exelon treatment group reported nausea compared with the Aricept treatment group. Vomiting was also reported as a significant side-effect, and three times as many patients in the Exelon treatment group experienced it, compared with the other group.
Also, twice as many patients in the Exelon treatment group discontinued treatment due to side effects compared with the Aricept treatment group. Almost twice as many patients were able to remain at the maximum daily dose of Aricept, 10 mg once a day, than the maximum daily dose of Exelon, 12 mg daily (6 mg twice a day).
During the 12-week, open-label trial, 111 patients (59% female) with an average age of 74.5 years (51-90 years) were randomized and treated with either Aricept or Exelon for 12 weeks. Patients were dosed according to the approved product labeling for each medication.
Patients in the Aricept group received 5 mg once daily for 4 weeks and 10 mg once daily thereafter, if tolerated. Patients in the Exelon group received 1.5 mg twice daily for 2 weeks with dose increases of 1.5 mg twice daily every 2 weeks until reaching 12 mg (6 mg twice daily), if tolerated. Patients who could not tolerate higher doses were allowed to continue in the study at the next lower tolerated dose. Patients who could not tolerate at least 5 mg daily of Aricept or 6 mg daily (3 mg twice daily) of Exelon were discontinued from the study.
In this study, the most frequent overall treatment-emergent adverse events for Aricept versus Exelon included nausea, vomiting, headache, anorexia, abnormal dreams, back pain, somnolence, and urinary tract infection.
Other data presented at the symposium included results from two 1-year, placebo-controlled clinical studies with Aricept. In the 1-year US study, patients treated with Aricept maintained function significantly longer (median time about 5 months longer) than those treated with placebo. In the multinational 1-year study, cognition was maintained at or near baseline for one year as measured by the Mini Mental State Examination (MMSE) in patients treated with Aricept.
Alzheimer’s disease, which is a progressive and degenerative brain disorder, impairs cognition and the ability to perform such daily living activities as handling money, using the telephone, grooming, etc. Approximately 15 million people suffer from AD worldwide.
First launched in the United States in February 1997, more than 1.2 million people have received a prescription for Aricept. The manufacturers of Aricept, Eisai and Pfizer Inc., funded these studies.