The incidence of cancer in Slovenia has been rising since 1950 leading to more frequent use of anticancer drugs. Oncology drugs, especially the oralones, are at high risk of
pharmacokinetic interactions with other drugs, possibly worsening treatment outcomes or causing adverseevents. The thesis aimed at investigating and comparing data on pharmacokinetics drug interactions in the Summary of Product Characteristics of oral anticancer drugs.
Overall, 35 oral anticancer drugs for the treatment of solid cancers, that gained first marketing authorization between 2010 and 2019, were included. The summaries of product
characteristics, approved by the European Medicines Agency and approved by the US Food and Drug Administration, were reviewed to retrieve data on pharmacokinetic interactions.
Among the included drugs, 30 were targeted drugs, 3 hormonal drugs and 2 cytostatics. Most anticancer drugs (29/35; 83%) inhibit or induce at least one CYP450 isoenzyme, most
commonly CYP3A4 (15/35; 43%). Anticancer drugs often acted as a weak inhibitor or inducer (13/35; 37%). An even larger proportion od anticancer drugs (32/35; 92%) inhibits
or induces at least one transport protein, most often P-glycoprotein or BCRP (both: 21/35; 60%). A total of 196 pharmacokinetic interactions were detected, which would affect the pharmacokinetic parameters of the anticancer drug in 51% (100/196). In the investigations of drug interactions index substrates (54/196; 28%), inducers (29/196; 15%) and inhibitors (37/196; 19%) were used. The American summaries of product characteristics reported less pharmacokinetics interactions (105) than the European ones (193), with interactions, which affect the pharmacokinetics of anticancer drugs, involving the CYP450, being based on in
vivo studies and discouraging concomitant use being reported more often (all Chi-square, p<0.001).
Anticancer drugs are prone to drug-drug interactions. Because oncology patients are often prescribed numerous drugs, it is necessary to adequately address drug interactions in each patient. The summaries of product characteristics provide detailed information on drug
interactions, however, these need to be researched, compared and evaluated in the context of each individual patient.
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