Ondansetron, a selective 5-HT3 antagonist, may lower mesolimbic dopaminergi
c hyperactivity. The present open-label pilot study evaluated the effect of
ondansetron in Tourette's syndrome. Six Tourette's syndrome men aged 14-48
years resistant to haloperidol participated in the study. Assessments incl
uded the Yale Global Tic Severity Scale (YGTSS), Yale-Brown Obsessive-Compu
lsive Scale (Y-BOCS), and Tourette's syndrome-Clinical Global Impression (T
S-CGI) scale. The maximal ondansetron dosage (8-16 mg per day) was given fo
r 3 weeks. Ondansetron treatment was associated with a significant decrease
in the severity of ties. Two patients showed a definite response (score im
provement of 40% or more), and two showed a probable response ( > 25%). Two
patients did not improve. Side-effects were transient and included abdomin
al pain (n = 5) and constipation (n = 2). Ondansetron may possess anti-tie
effects in some Tourette's syndrome patients. Int Clin Psychopharmacol 14:3
73-376 (C) 1999 Lippincott Williams & Wilkins.