Reducing Warfarin Interactions
It’s not uncommon for patients who take warfarin generic to be taking other drugs— or for those drugs to have a significant potential for interaction.
Researchers from Kaiser Permanente and Northwest Permanente in Portland, Oregon, and from Harvard University in Boston evaluated the effectiveness of electronic medical record alerts. In one retrospective review, they found 65% of patients taking warfarin received a concurrent prescription for at least one interacting drug that increased the risk of bleeding.
Their study involved 239 primary care providers at 15 clinics and 9,910 patients. The clinics received the alerts for the co-prescription of warfarin and five interacting medications: acetaminophen, non-steroidal anti-inflammatory drugs (NSAIDs), fluconazole, metronidazole drug, and sulfamethoxazole medication. All of the alerts were clearly identified as safety alerts; they included a short description of the clinical issue or risk and recommended medication alternatives.
At the baseline evaluation, nearly one third of the patients had one of the interacting study medications. The most common co-prescription was for warfarin and acetaminophen. The researchers also noted an immediate and continued decline in the prescribing of medications interacting with warfarin, for a 15% relative reduction by the 12th month.
Co-prescribing warfarin and potentially interacting medications is not necessarily contraindicated in all situations, the researchers acknowledge. In fact, they say, acetaminophen alone or in combination with narcotics is sometimes the best pain medication for patients taking warfarin. Similarly, the antibiotics targeted in their study might be the best or only choice. The coadministration of warfarin and acetaminophen remains an area of controversy, however.
They add that their definition of co-prescribing was conservative; that is, they counted a prescription overlap of even a single day.
