Toxicity study in juvenile rats with the α4β2 nicotinic acetylcholine receptor partial agonist CP-601,927

CP-601927 is a selective α(4) β(2) nicotinic acetylcholine receptor (nAChR) partial agonist. The objective of this study was to assess the potential effects persisting into adulthood when CP-601,927 was administered to neonatal/juvenile rats. Since the juvenile toxicity study was being performed early in the development program and this study would represent the longest dosing period yet evaluated, the study design incorporated standard endpoints typically evaluated in a general toxicity screening study.

CP-601,927 was administered to Sprague-Dawley rats from postnatal day (PND) 7-70 by oral gavage at doses of 0.3, 1, or 3 mg/kg. During treatment animals were evaluated for growth, development, and sexual maturation. At the end of the treatment period general toxicity screening endpoints were collected (e.g., organ weights, histology, clinical chemistry). Following a 2-week latency period, animals were evaluated for CNS function in a comprehensive behavioral training battery consisting of a functional observational battery, motor activity, acoustic startle response, and learning and memory evaluations. Reproductive competency was evaluated by mating treated rats and allowing pregnant dams to deliver and rear their litters until PND 10.

Treatment-related findings included the death of 2 males receiving 3 mg/kg CP-601,927, and transient reductions in body weight for both males and females during the third week of dosing which quickly recovered to control levels. The only treatment-related alteration in behavior was decreased motor activity, which occurred only in females at the highest dose tested. CP-601,927 had no effect on acoustic startle response, learning and memory, sexual maturation, reproductive capacity, or general toxicity endpoints.