OBJECT DRUGS

Antipsychotics, Atypical:

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

PRECIPITANT DRUGS

• Fluvoxamine (Luvox, etc.)

Comment:

Agents that inhibit CYP1A2 and possibly CYP2C19 increase antipsychotic plasma levels. Fluvoxamine has a marked effect, and can increase serum clozapine concentrations up to 5-10 fold. Fluvoxamine has been used to increase clozapine efficacy in patients with resistant schizophrenia, but careful monitoring is necessary to avoid clozapine toxicity. Some other SSRIs may produce modest increases in clozapine plasma concentrations, including fluoxetine, paroxetine and sertraline.

Class 2: Use Only if Benefit Felt to Outweigh Risk

• Use Alternative:Fluoxetine (Prozac), paroxetine (Paxil), and sertraline (Zoloft) appear to interact less than fluvoxamine. Theoretically, venlafaxine (Effexor) would be even less likely to interact, but information is lacking.
• Monitor:Monitor for altered antipsychotic response if a CYP1A2 inhibitor such as fluvoxamine is initiated, discontinued, or dose is changed.