title: Effects of a smoking ban on clozapine plasma concentrations in a nonsecure psychiatric unit.
abstract: BACKGROUND
  Tobacco smoke is known to affect plasma levels of some drugs, including the antipsychotic clozapine. The effects of suddenly stopping smoking on patients who take clozapine can be severe, as plasma concentrations are expected to rapidly rise, potentially leading to toxicity. A ban on smoking at South London and the Maudsley NHS Foundation Trust (SLaM) was implemented in 2014, and this was expected to affect the plasma concentrations of clozapine for inpatients at the time. This study aimed to determine whether plasma concentrations of clozapine were affected, and additionally, in line with observations from other authors, whether levels of reported violence would also be affected.
  
  
  METHODS
  The smoking habits of all patients at SLaM who smoked and were prescribed clozapine were recorded both before and after the ban. The Glasgow Antipsychotic Side Effect Scale for Clozapine (GASS-C) scale was used to evaluate side-effect burden. Clozapine doses and plasma concentrations were also collected.
  
  
  RESULTS
  In total, 31 patients were included in this study. The mean clozapine dose before the ban was 502 mg/day, and this did not change significantly after the ban. Similarly, there were no significant changes in clozapine or norclozapine plasma concentrations, or in GASS-C scores. There was no change in the amount of tobacco patients reported smoking before or after the ban. A modest but statistically significant reduction in violent incidences was observed.
  
  
  CONCLUSIONS
  Our data suggest that a ban on smoking for patients taking clozapine on open wards at inpatient hospital sites had little impact on clozapine plasma concentrations, because patients continued to smoke tobacco if allowed to leave. Smoking bans may result in a reduction in violent incidences.
authors.affiliation: Pharmacy Department, South London and Maudsley NHS Foundation Trust, London, UK.
authors.forename: Siobhan H
authors.initials: SH
authors.lastname: Gee
authors.affiliation: Institute of Pharmaceutical Science, King's College London, 16 De Crespigny Park, Camberwell, London SE5 8AF, UK.
authors.forename: David M
authors.initials: DM
authors.lastname: Taylor
authors.affiliation: Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK.
authors.forename: Sukhwinder S
authors.initials: SS
authors.lastname: Shergill
authors.affiliation: Toxicology Unit, Clinical Biochemistry, King's College Hospital NHS Foundation Trust, London, UK.
authors.forename: Robert
authors.initials: R
authors.lastname: Flanagan
authors.affiliation: Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK.
authors.forename: James H
authors.initials: JH
authors.lastname: MacCabe
keywords: antipsychotic agents; clozapine; smoking; violence