Underreporting of herb-drug interactions

An article in the most recent issue of Annals of Pharmacotherapy concludes that the vast majority of known cases of herbal medicine interactions with drugs go unreported. Researchers at the University of Alberta, University of Toronto, and Health Canada surveyed 132 pharmacists. While 47% of pharmacists had identified an herb-drug interaction, only 2 (1.5%) reported their cases to Health Canada.

But, according to the study authors, "19% of pharmacists said they had reported adverse events from mixing prescription and non-prescription drugs."

Why do pharmacists feel that reporting herb-drug interactions are any less deserving of their effort?

Underreporting of drug interactions is notorious in health care primarily due to the amount of paperwork or effort it takes to document cases (in the US, health professionals and patients can report suspected interactions to FDA's MedWatch program.). But it is interesting that the rate of reporting of herb-drug interactions was so much lower than for drug-OTC drug interactions.

The CBC story on this report doesn't address this particular problem but notes:

The adverse effects of taking prescription drugs with natural health products are dramatically under-reported or not reported at all, so their potential risks may be underestimated by health-care professionals and the public, the study found.

"We didn't anticipate the number of potential natural health product-drug interactions that community pharmacists were seeing, nor did we anticipate their reporting levels," said [lead author Dr Sunita] Vohra.

Interestingly, the US passed legislation last year that will initiate an adverse event reporting system for herbal products and herb-drug interactions that will be enforced later this year.

But no matter how good any reporting system is, information cannot be disseminated if reports are not made. But time demands on all health professionals put this task somewhat low on their to-do lists.

Hat tip: PharmCanuck