OBJECT DRUGS

Antipsychotics:

• Clozapine (Clozaril, etc.)
• Olanzapine (Zyprexa, etc.)

PRECIPITANT DRUGS

Smoking Cessation Drugs:

• Bupropion (Zyban, etc.)
• Nicotine (Nicorette, Nicoderm, Nicotrol, etc.)
• Varenicline (Chantix)

Comment:

Patients on clozapine or olanzapine who stop smoking may develop substantial increases in plasma concentrations of the antipsychotic because smoking markedly enhances the activity of CYP1A2 (important in the metabolism of clozapine and olanzapine). The magnitude of the increase in clozapine or olanzapine levels is highly variable, with some people manifesting dramatic increases and some others developing only small effects.

Class 3: Assess Risk & Take Action if Necessary

• Monitor:In a patient on clozapine or olanzapine the addition of a smoking cessation drug should be a signal to monitor for evidence of antipsychotic toxicity. Reduce clozapine or olanzapine dose as necessary.