After screening, eligible participants will start the placebo baseline ambulatory phase (4 days). On day 5, they will be hospitalized for three to five days, to undergo a "baseline" 72-hour CFA determination under a controlled diet and using a stool marker to indicate the beginning and end of the controlled diet period, while they continue receiving placebo treatment. At the end of the placebo baseline phase, participants will be randomized to a "high dose followed by a low dose" or to a "low dose followed by a high dose" EUR-1008 (APT-1008) dose sequence and proceed to the first crossover (treatment) phase. Each crossover (treatment) phase will consist of a stabilization period for six days at home, followed by a hospitalization of three to five days to undergo a 72-hour CFA determination using a controlled diet and using a stool marker to indicate the beginning and end of the controlled diet period.