title: Effect of influenza vaccination on serum clozapine and its main metabolite concentrations in patients with schizophrenia.
abstract: OBJECTIVE
  To study the effect of influenza vaccine on serum clozapine, N-desmethylclozapine and clozapine-N-oxide steady-state concentrations in patients with schizophrenia.
  
  
  METHODS
  This was an open-label study in 14 schizophrenic inpatients (with 2 drop-outs) using clozapine. Serum trough concentrations of clozapine. N-desmethylclozapine and clozapine-N-oxide, as well as the concentration of c-reactive protein (CRP), were measured immediately before conventional trivalent influenza vaccination and 2, 4, 7 and 14 days after the vaccination.
  
  
  RESULTS
  Influenza vaccination had no significant effect on serum concentrations of clozapine, N-desmethylclozapine or clozapine-N-oxide. No changes in the clinical effects of clozapine were observed after vaccination. Influenza vaccination did not increase CRP. However, two drop-out patients who developed upper respiratory and abdominal symptoms had increased and elevated serum concentrations of clozapine, compared with the baseline.
  
  
  CONCLUSIONS
  Influenza vaccination using conventional trivalent influenza vaccine does not affect serum concentrations of clozapine or its main metabolites. However, an infection-related increase in CRP may be associated with increased serum concentration of clozapine.
authors.affiliation: Department of Clinical Pharmacology, University of Helsinki, Finland. kari.raaska@hus.fi
authors.forename: K
authors.initials: K
authors.lastname: Raaska
authors.forename: V
authors.initials: V
authors.lastname: Raitasuo
authors.forename: P J
authors.initials: PJ
authors.lastname: Neuvonen
mesh_terms: D000328:Adult; D014150:Antipsychotic Agents / Q000097:blood / Q000493:pharmacokinetics* / Q000627:therapeutic use; D002097:C-Reactive Protein / Q000378:metabolism; D003024:Clozapine / Q000031:analogs & derivatives* / Q000097:blood / Q000493:pharmacokinetics* / Q000627:therapeutic use; D004347:Drug Interactions; D005260:Female; D006801:Humans; D007252:Influenza Vaccines / Q000494:pharmacology*; D008297:Male; D008875:Middle Aged; D012559:Schizophrenia / Q000097:blood / Q000188:drug therapy; D014611:Vaccination
chemical_list: D014150:Antipsychotic Agents; D007252:Influenza Vaccines; C058272:norclozapine; D002097:C-Reactive Protein; D003024:Clozapine; C079149:clozapine N-oxide