The major kratom alkaloids likely cause significant drug-drug interactions when they are coadministered with drugs that are primarily metabolized by this P450 isoenzyme?
A recent in-vitro study done by Kamble SH reveals that mitragynine and corynantheidine, two alkaloids of kratom, inhibit CYP 2D6. (Kamble, Shyam H., et al. "Exploration of Cytochrome P450 Inhibition Mediated Drug-Drug Interaction Potential of Kratom Alkaloids." Toxicology letters (2019))