Unbeknownst to many physicians, bottles of the new oral anticoagulant dabigatran (Pradaxa) must be used within 30 days of opening, according to information from the manufacturer.
The lid of the bottle contains a desiccant to keep capsules of the drug stable, and humidity can quickly degrade the compound after the seal is removed, said the drugmaker Boehringer Ingelheim.
However, few researchers contacted by ڴŮ were familiar with the 30-day limitation.
Steven Nissen, MD, of the Cleveland Clinic, said he hadn't yet heard of the issue, but called it "troubling."
"It's very unusual," Nissen told ڴŮ. "It's a real problem."
Many drugs remain stable after the bottle cap has been removed for far longer periods of time, such as one year.
Patients would have a problem if they received more than a month's supply of Pradaxa capsules and opened both bottles -- rendering the second month's drug supply ineffective.
Company spokesperson Anna Moses told ڴŮ that "directions to use Pradaxa within 30 days of opening the bottle are found on the Pradaxa package, prescribing information, and medication guide."
She added that the drug is available in both a bottle and in blister packs -- the latter of which may be the better strategy for reducing chances of drug degradation. The bottle contains 60 Pradaxa capsules, a one-month supply, and the blister pack is a 10-by-6 capsule card.
Moses said the company conducted stress stability studies to assess the effects of heat, humidity, and light on the drug's integrity. The results suggested that the recommended shelf life of Pradaxa is 24 months at 77 degrees Fahrenheit if the bottle is unopened.
However, once the bottle is opened, the capsules should be used within 30 days, she said.
The oral direct thrombin inhibitor was approved by the FDA last October to prevent stroke and blood clots in patients with atrial fibrillation.