Klin Farmakol Farm. 2025;39(3):181-184 | DOI: 10.36290/far.2025.063

Pharmacokinetic interactions of clozapine and olanzapine: case studies of drug modifications due to CYP1A2 inhibition

Kateřina Skopalová

Pracoviště klinického farmaceuta, Psychiatrická nemocnice v Kroměříži

MARTA antipsychotics are essential drugs in the treatment of psychiatric disorders; however, their efficacy and safety can be affected by drug interactions. This article focuses on interactions between antipsychotics and antibiotics, particularly through the inhibition of cytochrome P450 1A2 (CYP 1A2), which may lead to drug level changes beyond the therapeutic range. Two selected case reports from clinical practice in an inpatient psychiatric hospital illustrate the consequences of these interactions and possible solutions. Special emphasis is placed on the drug interaction between clozapine and ciprofloxacin and the necessity of therapeutic drug monitoring (TDM), potentially in combination with pharmacogenetic testing. A key theme is also the optimization of antipsychotic and antibiotic therapy in patients with comorbidities, requiring close collaboration between clinical pharmacists, psychiatrists, and other specialists. The article highlights the role of the clinical pharmacist in interdisciplinary communication regarding drug interactions, individualization of pharmacotherapy, and prevention of adverse effects. It also discusses the need to integrate pharmacogenetics into clinical practice as a tool for optimizing the treatment of psychiatric patients.

Keywords: clinical pharmacy, antipsychotics, antibiotics, drug interactions, cytochrome P450, therapeutic drug monitoring.

Accepted: October 23, 2025; Published: October 30, 2025  Show citation