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Unsafe Interaction Between Pradaxa and Common Calcium Channel Blockers
An observational study published in 2020 found that people with A-Fib taking two common rate control calcium channel blockers along with the anticoagulant Pradaxa had higher bleeding rates (GI bleeding, minor bleeding, and minor GI bleeding).
The study was an analysis of the potential drug-drug interaction between verapamil or diltiazem and DOACs.
The term DOAC has replaced use of NOAC.
The study was conducted using US population-based data (2010-2015) analyzed between January 1 and July 15, 2019. Data were obtained on 48,442 patients with nonvalvular atrial fibrillation who had received an index prescription of dabigatran, rivaroxaban, or apixaban.
Analysis was restricted to individuals with no history of kidney disease who were receiving standard doses of the DOACs.
Drug-Drug Interactions Found When Co-Administered
Researchers found that taking the drugs Verapamil and Diltiazem (rate control calcium channel blockers) along with the anticoagulant Pradaxa had higher bleeding rates.
Other anticoagulants such as Xarelto and Eliquis didn’t cause more bleeding. (Apixaban [Eliquis] had consistently lower bleeding event rates among all DOACs.)
(For you technical types, Dabigatran functions as a P-glycoprotein inhibitor (P-gp), an important protein that pumps many foreign substances, such as toxins and drugs, out of cells. Verapamil and diltiazem are also P-gp inhibitors.)
Pradaxa Data Compiled and Compared to Four Calcium Channel Blockers
The investigators compiled data from IBM Watson MarketScan Databases.
Comparisons were made between 1,764 Pradaxa (dabigatran etexilate) users taking verapamil or diltiazem versus 3,105 Pradaxa users taking amlodipine (a calcium channel blocker used primarily to lower blood pressure which isn’t a P-gp inhibitor). The overall bleeding rate was 52% higher compared to amlodipine.
In addition, comparisons were made between 1,793 Pradaxa users taking verapamil or diltiazem versus 3,224 Pradaxa users on metoprolol (a beta-blocker which isn’t a P-gp inhibitor). The overall bleeding rate was 43% higher compared to metoprolol.
Avoid Mixing Pradaxa with Verapamil & Diltiazem
The message of this study is clear. “Clinicians and patients may need to consider alternative DOAC therapy other than dabigatran” when using P-gp inhibitors such as verapamil and diltiazem. (Amiodarone is another P-gp inhibitor.) “It is not safe to combine dabigatran (Pradaxa) with P-glycoprotein (P-gp) inhibitors in people with atrial fibrillation (Afib)” regardless of kidney function.
What This Means to Patients
If you are taking the anticoagulant Pradaxa, along with Verapamil and Diltiazem (rate control calcium channel blockers), talk to your doctor about changing to another DOAC (and take a copy of this article with you).
Happily, there are several DOACs, so there’s seldom an overwhelming need to continue on Pradaxa (dabigatran). Eliquis (apixaban), for example, tested the best and is the safest of the DOACs.
