title: Rechallenge with clozapine following leucopenia or neutropenia during previous therapy.
abstract: BACKGROUND
  Further treatment with clozapine is contraindicated in any patient who has previously experienced leucopenia or neutropenia during clozapine therapy.
  
  
  OBJECTIVE
  To investigate the results of such a rechallenge in 53 patients.
  
  
  METHODS
  An analysis was made of the demographic, haematological and outcome data of patients in the UK and Ireland who were rechallenged with clozapine following leucopenia or neutropenia during previous clozapine therapy.
  
  
  RESULTS
  Of 53 patients who were rechallenged, 20 (38%) experienced a further blood dyscrasia. In 17 of these 20 patients (85%) the second blood dyscrasia was more severe (P<0.001), in 12 (60%) it lasted longer (P=0.0368) and in 17 (85%) it occurred more quickly on rechallenge (P<0.001). Of the original 53 patients, 55% (29 patients) are still receiving clozapine.
  
  
  CONCLUSIONS
  No clear risk factor for repeat blood dyscrasias was identified. Despite this, after risks and benefits have been considered, rechallenge may well be justified in some patients.
authors.affiliation: Histopathology Department, Leicester Royal Infirmary, Infirmary Square, Leicester LE1 5WW, UK. louisa.dunk@btinternet.com
authors.forename: Louisa R
authors.initials: LR
authors.lastname: Dunk
authors.forename: Linda J
authors.initials: LJ
authors.lastname: Annan
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Andrews
mesh_terms: D000328:Adult; D014150:Antipsychotic Agents / Q000009:adverse effects* / Q000627:therapeutic use; D003024:Clozapine / Q000009:adverse effects* / Q000627:therapeutic use; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D007970:Leukopenia / Q000139:chemically induced*; D008297:Male; D008875:Middle Aged; D009503:Neutropenia / Q000139:chemically induced; D012008:Recurrence; D018570:Risk Assessment; D012559:Schizophrenia / Q000188:drug therapy*; D013997:Time Factors
chemical_list: D014150:Antipsychotic Agents; D003024:Clozapine