PET Imaging Study to Evaluate the mGlu5r Occupancy Following ADX48621 (Dipraglurant) Administration

This is an open label study, non-randomized, positron emission tomography (PET) study investigating mGlu5 receptor occupancy after single or two oral dosing of ADX48621 in healthy subjects using \[18F\]-FPEB . The study consists of 2 parts. Part 1: A receptor occupancy dose curve will be obtained by using an adaptive design. Subjects will undergo two \[18F\]-FPEB PET imaging sessions: a baseline plus a scan after treatment with one dose of ADX48621. The second scan will be taken at Tmax for ADX48621 (1 hour post dose). 100 mg will be the initial dose as this has been proven to be efficacious in a P2A study in Parkinson's patients. This is an open label study, non-randomized, positron emission tomography (PET)study investigating mGlu5 receptor occupancy after single or two oral dosing of ADX48621 in healthy subjects using \[18F\]-FPEB as the radiotracer.The maximum dose to be given will be 200 mg. Part 2: The time course of the receptor occupancy will be studied for the dose which gives 70% receptor occupancy as determined in Part 1. Two subjects will receive 2 doses of ADX48621 on 2 separate days and undergo three \[18F\]-FPEB PET imaging sessions: a baseline scan, post dose scan 1 and post dose scan 2. Subjects will be given ADX48621 one hour prior post dose scan 1. The 2nd dose will be given in the morning approximately 4-6 hours prior of the post dose scan 2. The post dose scan 2 will be performed in the afternoon. The maximum dose to be given will be 400 mg.