In research presented at a major medical conference, researchers have found that as many as one-third of patients on newer-generation blood thinners like Eliquis are taking the wrong dose.

Blood thinners or anticoagulants are drugs designed to interfere with the body’s ability to form blood clots. While blood clotting is a part of the normal healing process, when blood clots form inside the body, they can block the blood supply to important organs and tissues, causing stroke, pulmonary bleeding, certain types of heart attack, and other blood thinner complications depending on where the clot gets stuck.

Anticoagulants like Eliquis are designed to make it harder to form blood clots for individuals for risk factors for stroke and other clot disorders. For example, a type of abnormal heartbeat called atrial fibrillation or A-fib is a major risk factor for stroke, and atrial fibrillation patients are often prescribed Eliquis to reduce their risk of stroke. But newer anticoagulants like Eliquis may carry risks of their own.

In this new research, a team from the Fairleigh Dickinson University School of Pharmacy in New Jersey looked at 21 patients in an intensive care unit. Researchers found that seven out of the 21 patients were taking the wrong dose of their newer-generation blood thinners.

Specifically, the researchers found that when doctors prescribed drugs like Eliquis, they often did not take into account kidney problems. Normally, the kidneys filter Eliquis and other anticoagulants from the blood, but in patients with impaired kidney function, this takes longer, and a smaller dose of Eliquis will have a greater effect. The authors of the study found that four of the seven patients on the wrong dose were prescribed the wrong dose due to physicians overlooking kidney function. One of these four patients was in the ICU for uncontrolled bleeding.

The researchers in this study acknowledged that many doctors do not test patient’s kidney function before prescribing a next-generation blood thinner like Eliquis, as these drugs are often prescribed to patients with a great risk of life-threatening risks. But the researchers stressed that it’s worth waiting for the results of kidney function tests when as many as a third of patients taking drugs like Eliquis are taking the wrong dosage.

Eliquis Side Effects

The researchers also pointed out the fact that older anticoagulants like Warfarin have known reversal agents. This means that if a patient experiences internal bleeding on Warfarin or related drugs, doctors can give them a second drug which stops the bleeding. Newer-generation anticoagulants like Eliquis do not have known reversal agents, making it much harder for doctors to treat internal bleeding when it happens. Researchers stated the risk of internal bleeding with no way to reverse it made it a priority to figure out if a patient’s dose of Eliquis is too high.

All anticoagulants, including Eliquis, carry the risk of working too well. In some patients, these drugs can completely strip the ability to form blood clots. This means a person can bleed to death from very minor injuries. Even unseen internal injuries can cause life-threatening internal bleeding. Older-generation anticoagulants like Warfarin come with a warning that physicians should test the blood of patients on anticoagulants. Newer anticoagulants like Eliquis are marketed as being safer and not requiring such blood tests. However, new evidence—and legal action—suggests otherwise.