title: Effect of anticholinergics in preventing acute deterioration in patients undergoing abrupt clozapine withdrawal.
abstract: BACKGROUND
  The most serious adverse effect of clozapine, agranulocytosis, was described for the first time in Finland in 1975. It caused the immediate withdrawal of clozapine from the market and immediate discontinuation of this medication in all patients. It is now known that abrupt withdrawal of clozapine may cause a rapid deterioration in psychotic symptoms.
  
  
  OBJECTIVE
  The aim of this retrospective study was to investigate the effect of abrupt clozapine withdrawal on psychiatric patients, and to examine whether anticholinergic drugs are effective in preventing acute deterioration.
  
  
  METHODS
  We reviewed the hospital case records from Pitkäniemi Psychiatric Hospital, Tampere, Finland, of the 28 patients with schizophrenia who had been receiving clozapine and from whom it was abruptly withdrawn due to the withdrawal of the drug from the market in the summer of 1975. We assessed the incidence of deterioration and whether or not patients in whom this occurred were receiving anticholinergic drugs.
  
  
  RESULTS
  We found a rapid deterioration after clozapine withdrawal in almost half (46.4%; n = 13) of the patients. Patients receiving anticholinergic drugs (such as antiparkinsonians, tricyclic antidepressants and antipsychotics with anticholinergic properties) were significantly less likely to deteriorate than those not receiving these drugs (21.4% vs 71.4%, p = 0.008). The condition of the patients who deteriorated was poor for up to 1 month after discontinuation, but had improved slightly by the end of 1975.
  
  
  CONCLUSIONS
  Anticholinergic medication should be considered for preventing possible symptom deterioration when clozapine is abruptly discontinued.
authors.affiliation: Harjavalta Hospital, Harjavalta, Finland. niko.seppala@satshp.fi
authors.forename: Niko
authors.initials: N
authors.lastname: Seppälä
authors.forename: Carita
authors.initials: C
authors.lastname: Kovio
authors.forename: Esa
authors.initials: E
authors.lastname: Leinonen
mesh_terms: D000293:Adolescent; D000328:Adult; D014150:Antipsychotic Agents / Q000009:adverse effects* / Q000627:therapeutic use; D018680:Cholinergic Antagonists / Q000627:therapeutic use*; D003024:Clozapine / Q000009:adverse effects* / Q000627:therapeutic use; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011569:Psychiatric Status Rating Scales; D012189:Retrospective Studies; D012559:Schizophrenia / Q000150:complications / Q000188:drug therapy; D012565:Schizophrenic Psychology; D013375:Substance Withdrawal Syndrome / Q000188:drug therapy*; D016896:Treatment Outcome
chemical_list: D014150:Antipsychotic Agents; D018680:Cholinergic Antagonists; D003024:Clozapine