A phase 1, safety, tolerability, and pharmacokinetics study of bisnorcymserine, a highly selective inhibitor of butyrylcholinesterase.

Cholinergic deficiency is a hallmark neurotransmitter abnormality in Alzheimer's disease (AD) that has traditionally been addressed with cholinesterase inhibitors. In severe AD, butyrylcholinesterase (BuChE) becomes the dominant cholinesterase, suggesting a potential therapeutic target. (-)-N1,N8-bisnorcymserine tartrate (BNC) is a selective BuChE inhibitor designed to address this unmet need. We conducted a phase I, single-center, randomized, double-blind, placebo-controlled, ascending single oral dose clinical trial to evaluate the safety, tolerability, and pharmacokinetics of BNC in 30 healthy volunteers. There were no adverse events (AEs) grade 2 or above or any serious adverse events (SAEs). Most events were mild and self-limited, the most common being asymptomatic bradycardia and headache. The mean AUClast (SD) was 120.98 h∗ng/mL (74.30) for the 40 mg dose, 148.20 h∗ng/mL (99.43) for the 80 mg dose, and 196.33 h∗ng/mL (91.74) for the 120 mg dose. Accordingly, median tmax (range) and mean Cmax (SD) were 1.8 (1.0-5.0) hr and 13.94 (7.64) ng/mL for the 40 mg dose, 1.8 (1.5-5.0) hr and 18.54 (6.44) ng/mL for the 80 mg dose, and 2 (1.0-4.5) hr and 20.93 (5.00) ng/mL for the 120 mg dose. The mean half-life of BNC ranged from 5.5 to 7 h. BNC was safe and well tolerated when administered as a single oral dose of up to 120 mg. This first-in-human, phase I study permits further investigation of this drug as a potential symptomatic treatment for AD. ClinicalTrials.gov, NCT01747213.