FDA warns Prilosec reduces effectiveness of Plavix by almost half

Prilosec OTC - the over-the-counter version of omeprazole
(photo by:cygnus921/Flickr/CC BY 2.0)

The U.S. Food and Drug Administration (FDA) has released a public health advisory against the combined use of the stomach acid-reducing medicine Prilosec and the anti-clotting medicine Plavix. New data shows omeprazole (Prilosec), reduces the effectiveness of clopidogrel (Plavix) by almost half when the medicines are used by the same patient.

Medical use of Plavix and Prilosec
Plavix is commonly prescribed to prevent blood clots and potential heart attacks in people who have chest pain, have had a heart attack, or medical procedures such as angioplasty or stenting. Unfortunately, the medication can have side effects, including bleeding in the stomach.

Omeprazole, sold by prescription as Prilosec or over-the-counter as Prilosec OTC, is in a group of medications known as proton pump inhibitors (PPIs). PPIs reduce the production of stomach acid by blocking an enzyme in the wall of the stomach that is responsible for producing acid. Prilosec is often used for reducing the frequent heartburn and potential stomach bleeding associated with taking Plavix.

Drug interaction between Plavix and Prilosec
Omeprazole inhibits the liver enzyme CYP2C19, which is required to metabolize Plavix and make it active in the body. The studies used by the FDA show the anti-blood clotting effect of Plavix was reduced by up to 47% when Prilosec was introduced into the system. The effect was the same if the two medications were used together or 12 hours apart.

Other medications to avoid while taking Plavix
The FDA warns the following anti-heartburn medications should be avoided while taking Plavix, as they have a similar effect as Prilosec:
Nexium
Tagamet and Tagamet HB

While there is currently no data available on the drug interactions between the following medications and Plavix, the FDA is concerned due to their effect on the CYP2C19 enzyme:
Diflucan
Nizoral
VFEND
Intelence
Felbatol
Prozac
Serafem
Symbyax
Luvox
Ticlid

The FDA recommends patients who use a combination of Plavix and any of the above-mentioned medications should consult with their doctor about treatment options available to them. Patients should not go off any medications without first talking to their doctor.

Alternative anti-heartburn medications to use while taking Plavix
The FDA feels the following anti-heartburn medications should be safe for Plavix users:
Antacids, such as Maalox or Mylanta
Zantac
Pepcid
Axid

Patients should talk to a doctor or pharmacist if they have any questions on which stomach acid-reducer is appropriate for their case.