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Be Careful Combining Blood Thinners & Other Medication

By Dr. David Moliterno 

People at risk of heart attack or stroke are often prescribed blood thinners to prevent dangerous clots from forming.  While these drugs can be true lifesavers, care must be used when combining them with other medications. 

In particular, some anti-ulcer and heartburn medications called proton-pump inhibitors have recently come under scrutiny because of suspicions they could interfere with a certain type of blood thinner. 

There are several blood-thinning medications that physicians can prescribe for patients at risk for heart attack or stroke.  All of them work by interfering with the clotting mechanism in one of two ways.  

Aspirin  and clopidogrel (Plavix) are used to block the function of platelets, tiny blood cells that act as the first line for making a clot. Warfarin (Coumadin) is used to block coagulation proteins, which are also required to make a blood clot.  

For some patients, the need to inhibit blood clots is especially critical, and two or three blood-thinning medications are needed in combination.  

The main drawback to using blood thinners is bleeding.  A common site of bleeding is in the stomach.  It makes sense then, that many patients who take blood-thinning medications might also be taking another medicine, particularly one to prevent an ulcer from forming.   

Since many medications to treat heartburn and ulcers are available without a prescription, patients sometimes take them without the involvement or knowledge of a physician.  This can be dangerous for patients taking other medications because of the potential for drug interaction. 

The Food and Drug Administration (FDA) recently issued a public health warning that some anti-ulcer medications, such as omeprazole (Prilosec), might reduce the ability of clopidogrel to prevent clots. This could be catastrophic for patients at high risk for heart attack or stroke.  

The FDA warning was issued after early studies suggested patients who were taking clopidogrel and an anti-ulcer medication in the proton-pump inhibitor class were slightly more likely to have a heart attack than patients not taking a proton-pump inhibitor. 

The information from these studies is complex. Not all doctors agree on their interpretation or on the FDA warning.  Many physicians do agree there is probably a small interaction between proton-pump inhibitors and clopidogrel. However, balancing the risks – between a blood clot and bleeding – often needs to be considered for one patient at a time.  

Fortunately, there are other common anti-ulcer medications, such as famotidine (Pepcid) and ranitidine (Zantac), that do not affect clopidogrel. 

Now more than ever, it is important to talk with your doctor and to be sure all your medications are in your records.

Dr. David Moliterno is a professor and chief of the Division of Cardiovascular Medicine at the University of Kentucky College of Medicine and medical director of the UK HealthCare Gill Heart Institute.