What’s the Problem?
Boehringer Ingelheim has stated that most of the deaths from Pradaxa were caused by bleeding complications. An updated list of fatalities was issued following an inquiry from Japan, where dozens of deaths have been associated with Pradaxa use.
In response to this alarming trend, Japan has called on Boehringer to add strengthened warnings to the labeling of Pradaxa.
Taking the high number of deaths into consideration, researchers have questioned the validity of Pradaxa clinical trials, stating that the drug should never have been approved because the studies were flawed.
Pradaxa was designed as a replacement for Coumadin (generic: warfarin) , but is supposed to require less patient monitoring and be easier to use.
However, warfarin can be counteracted with Vitamin K when an internal bleeding problem occurs. This does not work with Pradaxa or any of the other newer blood thinners such as Xarelto (generic: rivaroxaban).
This new class of medications - which also includes Eliquis (Bristol-Myers Squibb and Pfizer) and Lixiana (Daiichi Sankyo) - are used to prevent strokes in patients suffering from atrial fibrillation, or a-fib, a type of irregular heartbeat common among the elderly. All of these drugs are competing for a market estimated to be worth between $10 and $20 billion annually.
Like other blood-clotting agents, Pradaxa’s ability to treat massive strokes comes at the risk of internal bleeding, which can also be fatal. It has been theorized that Pradaxa may have too much of an effect on the blood clotting process, which leads to hemorrhages.
There have also been conflicting reports indicating that the drug does not have enough of an effect on clotting, resulting in pulmonary embolisms and deep vein thrombosis (DVT).
In recent studies, Pradaxa bleeding side effects included:
- Any bleeding - in up to 16.6% of people taking Pradaxa (compared to 18.4% with warfarin)
- Major (serious) bleeding - up to 3.3% (compared to 3.6% with warfarin)
- Life-threatening bleeding - up to 1.5% (compared to 1.9% with warfarin)
- Bleeding in the brain - up to 0.3% (compared to 0.8% with warfarin)
In Europe, doctors have been advised to test patients’ kidney functions to reduce chances of bleeding complications before starting Pradaxa. The drug was approved for use in the United Kingdom on November 1, 2011. In the U.S., Pradaxa was approved for use in October 2010, and has since received more customer complaints to the U.S. Food & Drug Administration (FDA) than about 99% of the other drugs on the market.
According to the Institute for Safe Medication Practices (ISMP), FDA received hundreds of reports of Pradaxa side effects within weeks of the drug being released.
Most of these side effects were internal bleeding problems in elderly patients. In total, the agency received over 300 complaints about Pradaxa in the last quarter of 2010 alone, compared to just 202 complaints involving warfarin.
Side Effects of Pradaxa
Pradaxa has been associated with the following serious side effects:
- serious internal bleeding
- serious internal hemorrhaging
- bleeding disorders
- rectal bleeding
- cerebral hemorrhage
- heart attack
- digestive tract ulcers
- kidney failure
- pulmonary embolism
- deep vein thrombosis
Moderate side effects of Pradaxa may include:
- abdominal (stomach) pain
- gastroesophageal reflux disease (GERD)
- ulcers of the digestive tract
Before Taking Pradaxa
To ensure you can take Pradaxa safely, tell your doctor if you have any of these other conditions:
- kidney disease;
- a history of stomach ulcer or bleeding; or
- if you are older than 75.
Pradaxa Pregnancy Category
FDA has classified Pradaxa as a Pregnancy Category C medication, which means that it is not currently known if the drug will harm an unborn baby.
You should consult your healthcare professional immediately if you are pregnant or planning on becoming pregnant while taking Pradaxa. Do not use this medication without telling your doctor if you are breast-feeding a baby.
Pradaxa Bleeding Studies
A recent analysis of internal bleeding injuries among Pradaxa users suggests that the risks of the medication may be greater than any potential benefit.
The review, which was published in the Feb. 2012 online edition of the Journal of the American College of Cardiology identified 78 internal bleeding events during the 60 day review period, including 44 cases handled by the panelists personally. Of these 44, at least 12 were classified as ‘severe.’
One of the major contributing factors to the internal bleeding events identified by the panel was that of prescriber error. A number of doctors were found to have prescribed Pradaxa to patients with pre-existing kidney damage, which has previously been identified as being one of the four major factors contributing to internal bleeding.
Impaired renal function makes it difficult for the body to filter out Pradaxa’s blood-thinning agents, thereby increasing the chance that internal bleeding events will become progressively severe.
In the RE-LY clinical trial, which the FDA used as justification for Pradaxa’s approval, less than 20% of the test subjects had prior kidney damage, compared to nearly 60% of the population from the new review.
Another major contributing factor identified by the panel was the issue of patient age. The average test subject age in the RE-LY trial was 71-years-old, and less than 30% of the population was over the age of 80. In the new study, more than two-thirds of the test subjects were older than 80-years-old.
This is an important distinction due to the fact that moderate kidney damage is reported in approximately half of all patients with atrial fibrillation (the condition for which Pradaxa is most often prescribed), and who are older than 80. As discussed above, pre-existing renal impairment increases the chance that a bleed will become severe.
Because the test subjects reviewed by the new study have significantly different demographics from that of the RE-LY trial, the panelists encouraged further investigation into the matter, and advised those who prescribe Pradaxa to weigh the risks versus benefits of the medication with patients carefully - especially in individuals over 80 or with pre-existing kidney damage - before prescribing the drug.
Pradaxa Labels Updated in Canada
Canadian health regulators have required new warning labels to be added to Pradaxa indicating the risk of internal bleeding may be increased in patients with kidney problems.
Health Canada also indicated that Pradaxa should not be used on individuals with rheumatic valvular heart disease, mitral valve stenosis, or prosthetic heart valves, as the safety of Pradaxa has not been tested in patients with these complications.
The new Canadian warnings are based on post-marketing reports of internal bleeding among elderly individuals being treated with Pradaxa, especially those with severe kidney problems. The level of kidney impairment can be determined by calculating the person’s creatinine clearance (CrCl). A CrCl of less than 30 mL/min is designated as severe renal damage.
Study Links Pradaxa to Heart Attack Risk
A recent meta-analysis published in the Archives of Internal Medicine has identified Pradaxa as being linked to myocardial infarction, or heart attack, and acute coronary syndrome compared to placebo.
According to researchers at the Cleveland Clinic, among randomized controlled trials for a variety of indications, myocardial infarction and acute coronary syndrome occurred at a substantially higher rate with Pradaxa when compared to control treatments (1.19% versus 0.79%; OR 1.33, 95% CI 1.03 to 1.71).
"Clinicians should consider the potential of these serious harmful cardiovascular effects with use of dabigatran," said Ken Uchino, MD, and Adrian Hernandez, MD, PhD, in Archives of Internal Medicine.
The meta-analysis evaluated Pradaxa as used for:
- stroke prevention in atrial fibrillation (versus warfarin)
- prophylaxis for acute venous thromboembolism (versus warfarin)
- deep venous thrombosis (versus enoxaparin)
- prevention of events in acute coronary syndrome (versus placebo)
The study was conducted to examine the risk of MI and acute coronary syndrome in diverse patient populations who were treated with Pradaxa. For purposes of analysis, individuals taking any dose of the drug were grouped together.
The research involved seven randomized controlled trials that included 30,514 test subjects. The control arms of the study included warfarin, enoxaparin, or placebo. The analysis concluded that Pradaxa was associated with a significantly higher risk of heart attack and acute coronary syndrome -- 0.27% (95% CI 0.04% to 0.50%).
Uchino and Hernandez stated that they were unaware of any pharmacologic mechanism to explain why Pradaxa may increase the risk for myocardial infarction or acute coronary syndrome. They speculated that it could be due to the medication’s chemical composition, or because the control drugs are better at preventing these conditions than Pradaxa.
Brain Hemorrhage Death
The death of an elderly man from brain hemorrhage after a routine fall suggests that bleeding complications from Pradaxa may be irreversible.
Three University of Minnesota doctors evaluated the events that led to the death of an 83-year-old man for what initially was seen as a routine fall, according to the Journal of Neurosurgery.
When the man was first admitted to the university’s medical center, he was fully alert and in control of his faculties, and his neurological examination showed no findings of great concern. CT scans revealed tiny superficial areas of hemorrhage in the brain, but within hours new scans revealed extensive progression of hemorrhaging. Unfortunately, efforts to reverse the complications proved ineffective, as the patient fell into a coma and subsequently died.
"In the event of traumatic hemorrhage in patients receiving dabigatran ... there are currently no effective reversal agents" to neutralize the drug, the report said.
Having an intimate understanding of Pradaxa interactions is of critical importance for medical personnel when using the drug to control bleeding, the report said.
The researchers speculated that emergency dialysis may be able to remove up to 60% of Pradaxa from the bloodstream in 2 to 3 hours, but that option was not used with the elderly patient.
Due to the fact that falls and general motor coordination problems are common in elderly individuals, brain hemorrhages from even minor trauma are likely to increase as more patients undergo treatment with Pradaxa, the report said.
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