My latest Medcast: a discussion of the association between Proton Pump Inhibitors and infectious diarrhea. 

November 8, 2010

There has been a lot of debate over the past couple of years about a possible drug interaction between proton pump inhibitors (PPIs) and Plavix. Every couple of months it seems there is a new publication that contradicts the previous thoughts on the significance of this interaction. Today, the American Heart Association and two other major cardiology groups issued a provisional guideline on what to do about this interaction. If you take Plavix, you should know how this affects you.

PPIs are stomach-acid reducing drugs. Popular brand names include Prilosec, Prevacid, Protonix and Aciphex. Many people use them for gastroesophageal reflux disease (GERD), as well as many other uses related to stomach problems.

Plavix is a blood thinning medication used to prevent heart attacks and strokes in people with cardiovascular disease, especially if they have had a heart attack or have had stents placed. While Plavix is very effective, it does increase the risk of gastrointestinal (GI) bleeding. For that reason, it is commonly used with a PPI to reduce that risk. Other acid-reducing therapies such as Zantac or Pepcid could be used as well, but they are not as effective at preventing GI bleeding.

PPIs have been shown to decrease the activity of an enzyme used to convert Plavix to its active form. See my previous posts on drug interactions and Plavix metabolism for a better explanation. This has been confirmed in several studies, and has also been shown to result in decreased blood thinning from Plavix. However, it has not been consistently shown to reduce the effectiveness of Plavix at preventing heart attacks and strokes. Because there hasn’t been a good enough study to date to show if this is a real problem or not, the decision to add a PPI to someone taking Plavix should be carefully considered in light of the theoretical risks.

It is being recommended that people on Plavix with the highest risk of GI bleeding still take a PPI. Those w/ the highest risk include persons who have had GI bleeding before, are of advanced age, or have been diagnosed with a stomach bacteria called helicobacter pylori. People who take NSAIDs such as ibuprofen or naproxen, or aspirin (which is commonly used w/ Plavix) should likely still take PPIs as well. If you do not have these risk factors, you probably shouldn’t take PPIs. If you have a lower risk of GI bleeding, Zantac or Pepcid might be better choices than a PPI. And if you are taking Plavix and a PPI, in theory it may be better to take them separately to help reduce the interaction (take Plavix in the morning and the PPI at bedtime). Keep in mind that these recommendations may change if and when we get more scientific information on this interaction.  

Aaron Emmel, PharmD