Omeprazole and Xalkori - 1264502

Dr. Walko has written about this issue previously:

"The official word on dosing crizotinib with drugs that change the stomach pH (most commonly H2 blockers like Zantac or Pepcid and proton pump inhibitors like Nexium, Prilosec, Axid, Protonix and others) is that no official dosing studies have been done. It appears from some of the early clinical data that lowering the pH in the GI tract would be expected to decrease bioavailability of the drug, which would mean less of the drug getting absorbed, but we don’t have official data on this. My recommendation would be to try to separate the PPI as much as possible from the crizotinib, but you have to consider to quality of life issues too.

"I will just comment that though there are some similarities between drugs like erlotinib and crizotinib and other -nibs like causing diarrhea and interacting with many drugs due to common metabolism pathways, dosing with food recommendations and other aspects often differ." - http://cancergrace.org/topic/alk-or-ros1-nsclc-patient-group/page/5/#po…

On the other hand, the Xalkori prescribing information states: "Gastric pH elevating medications: In healthy subjects, coadministration of a single 250 mg oral dose of crizotinib following administration of esomeprazole 40 mg daily for 5 days did not result in a clinically relevant change in crizotinib exposure." - http://labeling.pfizer.com/showlabeling.aspx?id=676#section-1

Although this study seems to indicate there isn't a significant interaction, it wouldn't be a bad idea to follow Dr. Walko's recommendation and separate the omeprazole dose from the crizotinib.

JimC
Forum moderator

Just wanted to say thanks, Jim, for finding the best answer we could have hoped for -- far better than any handwaving thoughts I might add with so little informaiton to go on.

-Dr. West