Results of a 52-week study published in the November issue of European Neurology, which shows that rivastigmine tartrate reduces the cognitive decline of people with mild to moderate Alzheimer's disease, were reported by Martin R. Farlow, professor and vice chairman for research, Department of Neurology, Indiana University School of Medicine.
Rivastigmine is a cholinesterase inhibitor marketed as Exelon® by the Novartis Pharmaceuticals Corp.
Dr. Farlow found that patients treated daily with 6 mg. to 12 mg. of rivastigmine had significantly better cognitive function over the course of 52 weeks than patients originally treated with placebo or who received lower doses of the drug.
The study was conducted in two phases. The first phase was a randomized, double-blind, placebo-controlled trial of 26-weeks duration. In the second phase, all patients were progressively increased to their maximum tolerated dosage, even those originally on placebo, up to 12 mg. a day.
"The original placebo patients who were switched to rivastigmine showed significant cognitive improvement, but did not quite catch up to the patients treated with 6 to 12 mg. daily from the start," said Dr. Farlow.
The effects of the treatment were assessed by evaluating patients with the Alzheimer Disease Assessment Scale - Cognitive Subscale (ADAS-Cog).
Patients treated with placebo during the 26-week trial, had a mean decline of 3.8 ADAS-Cog points. There were 545 patients who completed the initial phase of the trial and 532 then agreed to enter the six-month, open-label extension trial.
By the end of this 52-week trial, patients who originally received placebo during the first 26 weeks scored less improvement on the ADAS-Cog test than patients who received rivastigmine during the entire 52-week period. Patients who received the higher dose of rivastigmine from the beginning had higher ADAS-Cog scores at the end than either the original placebo or low-dose rivastigmine groups.
"This study suggests that early treatment with 6 to 12 mg. daily of rivastigmine may provide benefits that are lost if treatment is delayed," said Dr. Farlow. "The failure of delayed treatment to give the same benefits of earlier therapy is evidence that suggests rivastigmine may affect the biological progression of the disease."
This clinical trial was supported by Novartis and conducted at 22 sites across the United States.