OBJECT DRUGS
Antipsychotics, Atypical:
- Asenapine (Saphris)
- Clozapine (Clozaril, etc.)
- Olanzapine (Zyprexa, etc.)
PRECIPITANT DRUGS
Enzyme Inhibitors:
- Atazanavir (Reyataz)
- Caffeine
- Cimetidine (Tagamet, etc.)
- Ciprofloxacin (Cipro, etc.)
- Contraceptives, Oral
- Enoxacin (Penetrex)
- Mexiletine (Mexitil)
- Tacrine (Cognex)
- Zileuton (Zyflo, etc.)
Comment:
Agents that inhibit CYP1A2 and possibly CYP2C19 increase antipsychotic plasma levels. Enoxacin is a potent inhibitor of CYP1A2 and would be expected to markedly increase antipsychotic plasma concentrations; it should be considered a Class 2 interaction. Oral contraceptives are generally modest inhibitors of CYP1A2, and the degree of inhibition is likely to be highly variable depending on the dose of the contraceptive and specific patient characteristics. The ability of caffeine to increase clozapine concentrations has usually been observed after moderate to heavy caffeine use.
Class 3: Assess Risk & Take Action if Necessary
- Consider Alternative:
- Cimetidine: Famotidine (Pepcid), nizatidine (Axid), and ranitidine (Zantac) have minimal effects on drug metabolism.
- Ciprofloxacin or Enoxacin: Gemifloxacin (Factive), levofloxacin (Levaquin), lomefloxacin (Maxaquin), moxifloxacin (Avelox), and ofloxacin (Floxin), appear to have little effect on CYP1A2.
- Monitor: Monitor for altered antipsychotic response if a CYP1A2 inhibitor is initiated, discontinued, or dose is changed.