Clozapine concentration and adverse reactions: Impact of smoking

The atypical antipsychotic clozapine is uniquely efficacious in addressing treatment‐resistant schizophrenia. There are significant variations, however, in its pharmacokinetic profile among treated patients, resulting from altered metabolic capacity secondary to drug‐drug interaction and/or smoking status (Haring et al., 1989). Smoking cigarettes produces chemicals that act as potent inducers of the activity of CYP1A2, the primary enzyme responsible for the metabolism of clozapine to the active metabolite norclozapine.