[Effect of omeprazole on plasma concentration and adverse reactions of capecitabine in patients with colon cancer]

Re-thinking the possible interaction between proton pump inhibitors and capecitabine

Proton Pump Inhibitors (PPI) rank within the top ten most prescribed medications in Europe and USA. A high frequency of PPI use has been reported amongst patients undergoing chemotherapy, to mitigate treatment-induced gastritis or gastro-oesophageal reflux. Several recent, mostly retrospective, observational studies have reported inferior survival outcomes among patients on capecitabine who concomitantly use PPI. Whilst this association is yet to be definitively established, given the prominence of capecitabine as an anti-cancer treatment with multiple indications, these reports have raised concern within the oncological community and drug regulatory bodies worldwide. Currently, the leading mechanism of interaction postulated in these reports has focussed on the pH altering effects of PPI and how this could diminish capecitabine absorption, leading to a decrease in its bioavailability. In this discourse, we endeavour to summarise plausible pharmacokinetic interactions between PPI and capecitabine. We provide a basis for our argument against the currently proposed mechanism of interaction. We also highlight the long-term effects of PPI on health outcomes, and how PPI use itself could lead to poorer outcomes, independent of capecitabine.

Efficacy of capecitabine when used concomitantly with proton pump inhibitors in cancer patients: a systematic review

BACKGROUND

Capectiabine is an oral antineoplastic drug used in multiple malignancies. Proton pump inhibitors (PPI) have been proven to interact with other oral antineoplastic agents. In this systematic review we will summarize the clinical evidence on the efficacy of capecitabine when used concomitantly with PPI.

MATERIALS AND METHODS

We performed a systematic literature search on the main databases up to November 2019.

RESULTS

Nine studies met our inclusion criteria: 8 retrospective studies and 1 phase II clinical trial. Patients with colorectal, breast and gastroesophageal were represented. Four out of the 9 studies reported a shorter efficacy outcome in uni- or multivariate analysis when capecitabine was taken concomitantly with PPI than alone.

CONCLUSIONS

Up to date, the clinical evidence reported on the use of capecitabine concomitantly with PPI is scarce and shows conflicting results. While awaiting further data, avoiding misuse of PPI in cancer patients taking capecitabine is recommended.