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Potential interaction-related toxicity of clozapine

Marcin Siwek

Affiliacja i adres do korespondencji
Psychiatr Psychol Klin 2015, 15 (2), p. 86–91
DOI: 10.15557/PiPK.2015.0014
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Streszczenie

Clozapine is an agent which undergoes intensive cytochrome P450-mediated hepatic metabolism (mainly by 1A2 and, to a lesser extent, by 3A4 and 2D6). The combined use of clozapine with drugs that inhibit these isoenzymes, such as ciprofloxacin, erythromycin, fluoxetine, fluvoxamine, elevates clozapine serum levels, thus increasing the risk or severity of adverse effects and complications typical of clozapine therapy. At the same time, enzymatic inductors (e.g. rifampicin, phenytoin, carbamazepine, St. John’s wort, nicotine, cannabinols) might contribute to reduced efficacy or, after their rapid discontinuation, toxicity of clozapine. The occurrence of synergistic adverse effects due to pharmacodynamic properties is another aspect of the interactions of clozapine with other agents. Sedative, hypotonic, anticholinergic, myelotoxic, and convulsive effects might increase after a simultaneous use of clozapine and other agents inducing the same adverse effects. Clozapine should be used with particular caution during infectious diseases as some of antibiotics (e.g. macrolides) as well as other antimicrobials (e.g. fluorochinolones) and antifungals (mainly azoles) may, by inhibiting clozapine metabolism, increase its myelotoxicity. On the other hand, synergistic myelotoxic effects of clozapine and some of antibiotics (clindamycin, metronidazole) or antipyretic and anti-inflammatory agents (e.g. ibuprofen, paracetamol, metamizole) may occur. Due to the high risk of interactions, clozapine is intended mainly for monotherapy. However, knowledge of the pharmacokinetic and pharmacodynamic properties of clozapine, and thus its potential interactions, allows to include this agent, if necessary, in combined therapy, provided that the necessary precautions are taken.

Słowa kluczowe
clozapine, cytochrome P450, interactions