title: Influence of tiapride on platelet counts in healthy volunteers and patients with movement disorders.
abstract: BACKGROUND
  The selective D2 antagonist tiapride is administered in various movement disorders. Furthermore, there are indications that tiapride increases platelet counts.
  
  
  OBJECTIVE
  To characterize tiapride's potential to increase platelet counts in healthy subjects and patients with movement disorders.
  
  
  METHODS
  In Part A, 10 healthy volunteers received tiapride (300 mg/day) for 21 days in a longitudinal, prospective, open trial. One hundred healthy subjects served as controls. Part B was a retrospective analysis of 15 patients with movement disorders on tiapride [Huntington's disease (n=6), Morbus Little (n=3), hyperkinetic syndromes of undetermined etiology (n=3), blepharospasm (n=1), cervical dystonia (n=1), perioral dyskinesia (n=1)] and 15 age- and sex-matched controls.
  
  
  RESULTS
  Part A: Although serum prolactin levels increased by 526+/-14%, confirming good drug compliance, tiapride elicited only minor changes in platelet counts. Part B: Platelet counts correlated positively with the dose of tiapride (100-800 mg/day; r=.67; P=.007). Platelet counts were significantly higher in patients on tiapride compared to healthy age-matched controls (P<.001). Four patients responded to an increase in the tiapride dosage with an increase in platelet count by 97-173 cells/nl.
  
  
  CONCLUSIONS
  Three weeks of treatment with tiapride (300 mg/day) is insufficient to elevate platelet counts to a clinically relevant extent in young healthy volunteers. However, in elderly patients with movement disorders tiapride treatment is associated with markedly increased platelet counts.
authors.affiliation: Department of Clinical Pharmacology-TARGET, Vienna University, Währinger Gürtel 18-20, A-1090, Vienna, Austria. nicole.hergovich@univie.ac.at
authors.forename: Nicole
authors.initials: N
authors.lastname: Kotzailias
authors.forename: Josef
authors.initials: J
authors.lastname: Finsterer
authors.forename: Susanne
authors.initials: S
authors.lastname: Aull
authors.forename: Hans-Georg
authors.initials: HG
authors.lastname: Eichler
authors.forename: Barbara
authors.initials: B
authors.lastname: Pratscher
authors.forename: Bernd
authors.initials: B
authors.lastname: Jilma
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000367:Age Factors; D018726:Anti-Dyskinesia Agents / Q000494:pharmacology*; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009069:Movement Disorders / Q000188:drug therapy; D010976:Platelet Count; D013921:Thrombocytopenia / Q000188:drug therapy; D013976:Tiapamil Hydrochloride / Q000494:pharmacology*
chemical_list: D018726:Anti-Dyskinesia Agents; D013976:Tiapamil Hydrochloride