An orally bioavailable small-molecule inhibitor of tryptophan hydroxylase (TPH) with potential antiserotonergic activity. TPH inhibitor LX1032 binds to and blocks the activity of TPH, which may result in a reduction in peripheral serotonin (5-HT) production and improvement of serotonin-mediated gastrointestinal effects such as severe diarrhea. This agent does not cross the blood-brain barrier (BBB), thus CNS serotonin levels are unaffected. TPH, the rate-limiting enzyme in serotonin biosynthesis, is overexpressed in carcinoid tumor cells.