Background Imatinib is mainly metabolized by CYP3A4 and to a lesser extent by other isoenzymes, with N-desmethyl imatinib being its major equipotent metabolite. Being a CYP3A4 substrate, imatinib co-administration with CYP3A4 modulators would change its pharmacokinetic profile. The cancer chemoprevention potential and anticancer efficacy of many herbal products such as grape seed (GS) and green tea (GT) extracts had led to an increase in their concomitant use with anticancer agents. GS and GT extracts were demonstrated to be potent inhibitors of CYP3A4. The aim of this study is to investigate the effect of standardized GS and/or GT extracts at two different doses on the pharmacokinetics of imatinib and its metabolite, N-desmethyl imatinib, in SD-rats. Methods Standardized GS and/or GT extracts were administered orally once daily for 21 days, at low (l) and high (h) doses, 50 and 100 mg/kg, respectively, before the administration of a single intragastric dose of imatinib. Plasma samples were collected and analyzed for imatinib and N-desmethyl imatinib concentrations using LC-MS/MS method, then their non-compartmental pharmacokinetic parameters were determined. Results h-GS dose significantly decreased imatinib’s Cmax and the $$ {\mathrm{AUC}}_0^{\infty } $$ AUC 0 ∞ by 61.1 and 72.2%, respectively. Similar effects on N-desmethyl imatinib’s exposure were observed as well, in addition to a significant increase in its clearance by 3.7-fold. l-GT caused a significant decrease in imatinib’s Cmax and $$ {\mathrm{AUC}}_0^{\infty } $$ AUC 0 ∞ by 53.6 and 63.5%, respectively, with more significant effects on N-desmethyl imatinib’s exposure, which exhibited a significant decrease by 79.2 and 81.1%, respectively. h-GT showed similar effects as those of l-GT on the kinetics of imatinib and its metabolite. However, when these extracts were co-administered at low doses, no significant effects were shown on the pharmacokinetics of imatinib and its metabolite. Nevertheless, increasing the dose caused a significant decrease in Cmax of N-desmethyl imatinib by 71.5%. Conclusions These results demonstrated that the pharmacokinetics of imatinib and N-desmethyl imatinib had been significantly affected by GS and/or GT extracts, which could be partially explained by the inhibition of CYP3A-mediated metabolism. However, the involvement of other kinetic pathways such as other isoenzymes, efflux and uptake transporters could be involved and should be characterized. Graphical abstract

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