A retrospective evaluation of the impact of total smoking cessation on psychiatric inpatients taking clozapine

Objective: To investigate the effect of a complete smoking ban on a group of psychiatric inpatients maintained on the antipsychotic medication clozapine. Method: Retrospective data on clozapine dose and plasma levels were collected from a three month period before and a six month period after the introduction of the smoking ban. Results: Before the ban only 4.2% of patients who smoked had a plasma clozapine level >= 1000 mu g/l but after the ban this increased to 41.7% of the sample within the six month period following the ban despite dose reductions. Conclusion: Abrupt cessation of smoking is associated with a potentially serious risk of toxicity in patients taking clozapine. Plasma clozapine levels must be monitored closely and adjustments made in dosage, if necessary, for at least six months after cessation.