Lu 25-109, a muscarinic agonist, fails to improve cognition in Alzheimer's disease

Objective: To evaluate the therapeutic effect of the selective muscarinic receptor mi partial agonist, m2 antagonist, Lu25-109 - a compound that directly stimulates muscarinic cholinergic receptors-in patients with probable AD. Methods: A 6-month, randomized, double-blind, placebo-controlled, parallel group trial comparing three doses of Lu25-109 with placebo was carried out. A total of 496 patients with probable AD with a Mini-Mental State Examination score between 10 and 26 were enrolled at 29 centers and randomized to placebo or Lu25-109 25, 50, or 100 mg tid. The primary efficacy measures were the AD Assessment Scale-Cognitive subscale and the AD Cooperative Study Clinical Global Impression of Change. Secondary efficacy variables included the AD Cooperative Study Inventory of Activities of Daily Living and the Behavioral Symptoms in AD Scale. Results: In both an intent-to-treat and a completer's analysis there were no significant differences for either the two primary or the secondary variables. There was a trend for patients on the highest drug dose to worsen in the completer's analysis. Adverse events included dizziness nausea, diarrhea, fatigue, increased sweating, and anorexia, all of which increased with increasing drug dose. Conclusion: Lu25-109, a selective partial mi agonist and an m2/m3 antagonist, failed to improve cognition in patients with mild to moderate AD.