title: Frequency of allergic or hematologic adverse reactions to ticlopidine among patients with allergic or hematologic adverse reactions to clopidogrel.
abstract: BACKGROUND
  Clopidogrel and ticlopidine are structurally very similar. In patients with an allergic or hematologic adverse reaction to either one of these drugs, the likelihood that an allergic or hematologic adverse effect will develop to the other is unknown. It is also unknown whether a reaction to the second thienopyridine is likely to be life threatening.
  
  
  RESULTS
  Medical records from 2 academic institutions were reviewed to identify patients who had an allergic or hematologic adverse reaction to either of the 2 currently commercially available thienopyridines and who were subsequently prescribed the other thienopyridine. Patient demographics, details of the adverse reactions, and subsequent clinical course were reviewed. A total of 76 patients were identified with an allergic or hematologic adverse reaction to clopidogrel or ticlopidine who had also received the other thienopyridine. Fourteen (27%; 95% CI, 16 to 41) patients who had an allergic or hematologic adverse reactions to clopidogrel had a similar reaction to ticlopidine; none developed a life-threatening reaction. The most common reaction was a rash (93%).
  
  
  CONCLUSIONS
  In patients with an allergic or hematologic adverse reaction to one thienopyridine, there seems to be an increased frequency of such reactions to the other thienopyridine. However, no patient had a life-threatening reaction after exposure to the alternative thienopyridine.
authors.affiliation: Department of Cardiology, Geisinger Medical Center, Danville, PA 17822-3003, USA.
authors.forename: Juzar O
authors.initials: JO
authors.lastname: Lokhandwala
authors.forename: Patricia J M
authors.initials: PJ
authors.lastname: Best
authors.forename: Joseph H
authors.initials: JH
authors.lastname: Butterfield
authors.forename: Kimberly A
authors.initials: KA
authors.lastname: Skelding
authors.forename: Thomas
authors.initials: T
authors.lastname: Scott
authors.forename: James C
authors.initials: JC
authors.lastname: Blankenship
authors.forename: Jeremy W
authors.initials: JW
authors.lastname: Buckley
authors.forename: Peter B
authors.initials: PB
authors.lastname: Berger
mesh_terms: D000368:Aged; D000799:Angioedema / Q000139:chemically induced*; D000077144:Clopidogrel; D004342:Drug Hypersensitivity / Q000209:etiology*; D005076:Exanthema / Q000139:chemically induced*; D005260:Female; D006801:Humans; D008297:Male; D009503:Neutropenia / Q000139:chemically induced*; D010975:Platelet Aggregation Inhibitors / Q000009:adverse effects*; D012189:Retrospective Studies; D018570:Risk Assessment; D012720:Severity of Illness Index; D013921:Thrombocytopenia / Q000139:chemically induced*; D013988:Ticlopidine / Q000009:adverse effects* / Q000031:analogs & derivatives*; D014481:United States
chemical_list: D010975:Platelet Aggregation Inhibitors; D000077144:Clopidogrel; D013988:Ticlopidine