Some antacids interact with Plavix more

Taking the blood thinner Plavix along with some prescription antacids can reduce the effectiveness of the blood clot prevention, Health Canada says.

The department sent an advisory to health professionals and patients on Thursday warning that new evidence showed while some antacids called proton pump inhibitors interact with Plavix, not all reduce the effectiveness to the same degree. 

Plavix, known generically as clopidogrel, is a prescription blood thinner used to prevent blood clots that could lead to heart attack or stroke. It is given to patients with a history of heart-related problems. 

Proton pump inhibitors or PPIs are prescription antacids used to treat heartburn and stomach ulcers, which can occur as side-effects of Plavix.

"New studies have shown that, while PPIs do interact with Plavix, not all PPIs interact to the same degree: some have a strong effect on Plavix, while others do not," Health Canada said in a statement.

The labelling for Plavix has been updated with new recommendations regarding the use of PPIs:

• PPIs known to strongly or moderately reduce Plavix effectiveness should be avoided. Omeprazole (sold in Canada as Losec) is one of these. 
• If a PPI  must  be  used  in  a  patient  taking  Plavix, consider a  PPI  that does  not  interact  as  strongly.  Pantoprazole (sold as Pantaloc) is one of these. 

In 2009, labels on Plavix were updated to indicate that use of any PPI in patients taking the drug should be discouraged, as emerging data suggested that PPIs potentially reduced the ability of Plavix to protect against blood clots.

The latest update was based on studies that showed not all PPIs interact with Plavix equally, Health Canada said.

These proton pump inhibitors sold in Canada:

• Dexlansoprazole  (sold under  the  brand  name  Dexilant.
• Esomeprazole  (sold under  the  brand  name  Nexium  and  its  generic equivalent).
• Omeprazole  (sold under the  brand  name  Losec  and  its  generic  equivalents).
• Lansoprazole  (sold under the  brand  name  Prevacid  and  its  generic equivalents).
• Pantoprazole  (sold under  the  brand  names Pantoloc  and  Panto  IV,  and their  generic  equivalents).
• Pantoprazole/magnesium (sold under the brand name Tecta).
• Rabeprazole  (sold  under the  brand  name  Pariet  and  its  generic equivalents) 

PPIs are also available in combination with other drugs, such as Vimovo, which contains esomeprazole.