Published: August 2009

Clopidogrel and proton pump inhibitors - possible interaction

Information on this subject has been updated. Read the most recent information.

Prescriber Update 30(3): 18
August 2009

Prescribers are advised that Medsafe is reviewing a possible medicine interaction between clopidogrel and proton pump inhibitors.

Clopidogrel inhibits platelet function and is indicated for the prevention of vascular ischaemia associated with atherothrombotic events. Proton pump inhibitors are frequently co-prescribed with clopidogrel to reduce gastrointestinal irritation which can be associated with clopidogrel use.

Some published reports1,2 have suggested that concomitant use of proton pump inhibitors can reduce the efficacy of clopidogrel.

Medsafe has reviewed the available evidence relating to this risk and has required the data sheets for clopidogrel to be updated. This update includes additional information in the warnings and precautions section about genetic factors influencing clopidogrel metabolism, specifically in patients with genetically reduced CYP2C19 function. As a precaution the clopidogrel data sheets are also being updated to include information discouraging the use of concomitant medicines that inhibit CYP2C19 metabolism, e.g. omeprazole.

Medsafe is continuing to monitor the evidence in support of an interaction between clopidogrel and proton pump inhibitors. Further information will be communicated when the results of definative interaction studies currently underway become available and are fully analysed to determine their clinical significance.

Until these data are available Medsafe recommends that healthcare professionals continue their current prescribing practices for clopidogrel. However patients requiring concomitant treatment with a proton pump inhibitor should have their treatment reviewed. If possible an H2-receptor blocker and/ or antacid should be considered instead of a proton pump inhibitor in these patients.

  1. Ho PM, Maddox TM, Wang L et al. (2009) Risk of adverse outcomes associated with concomitant use of clopidogrel and proton pump inhibitors following acute coronary syndrome JAMA 301(9): 937-44.
  2. Juurlink DN, Gomes T, Ko DT et al. (2009) A population-based study of the drug interaction between proton pump inhibitors and clopidogrel CMAJ 180:713-8