Drug Interactions and Patient Awareness
We all know that there is risk in life. For patients taking medication, that risk may incrementally or exponentially increase based on a range of factors including genetics, diet, and medical history. Each time a patient is prescribed a medication, a risk/benefit analysis must be done.
This is a common practice: Information on allergies is collected and documented, as is past experience with like formulations. The advent of electronic health records has impacted this process, along with quality improvement efforts. Generally, at each encounter, patients are asked to confirm their current medications (ideally including OTC and herbal products), as well as known allergies or adverse reactions. When a new medication is prescribed, the system can quickly identify potential interactions.
While this systematic approach has likely caught interactions that could have been deadly, it has most likely also included many other less dangerous interactions. Before the prescription can be sent to the pharmacy, the prescriber has to acknowledge the risk and determine if the benefits outweigh the risk.
Sounds reasonable, right?
As patients, don’t we want to know that we’re being prescribed something that won’t harm us? Of course we do! And we count on our doctors and pharmacists to keep us safe. So, when that prescription gets to the pharmacy, a similar process happens. The new medication is compared to what is on file at the pharmacy. Once it passes that safety check, a claim is likely submitted to the insurance company. The insurance company, in turn, will run its own screening process to see if the new medicine might interact with any other medications for which it has paid (this could be a different drug list than those maintained by the doctor or pharmacy).
This all sounds good. There are multiple checks before the medication is in the hands of the patient. So why do patients still suffer adverse events, including allergic reactions?
There are a number of reasons:
- Genetic predisposition — The patient could be genetically predisposed to react in a certain way to a chemical formulation. Unless and until we get to a point where patient’s genetic markers are fully documented in their medical records and we test chemical formulations against individual genes and genomic sequences, this risk will remain. While pharmacogenomics is an expanding field that is starting to have an impact on medication safety, today, we are still more likely to test a patient to determine if they are likely to respond to a certain treatment (think the BRCA gene in breast cancer) than we are to test if they will have an adverse reaction. We may be able to leverage family history to avoid some adverse reactions, but that is an inexact science.
- Incomplete labeling — We know that during drug development, manufacturers document adverse events and quantify the risk based on the number of patients affected. But if one patient in 100,000 has a reaction, that may not be considered significant enough to be included in the product information that is disseminated to prescribers and patients. Again, this is an inexact science. Not every reaction will be identified in the research that is done before a product is introduced to the market, nor will every reaction be directly linked to the product, or severe enough among a large percentage of the trial patients to warrant inclusion. Additional surveillance and voluntary reporting may identify other patients who have similar reactions, and updated information may be published to assist prescribers and patients in making informed choices about treatment.
- Patient compliance and understanding — Much of the safety processes are incumbent upon patients sharing complete, accurate, and timely information about their medical experiences. This is inherently a dangerous assumption. We know that patients don’t tell all the doctors everything, that they may prefer to pay cash for a prescription so their insurance company doesn’t get a claim, and that they may use multiple pharmacies. They may not want to change their dietary habits, such as a morning glass of grapefruit juice. Health information exchange has greatly improved providers’ ability to access a patient’s medical information; they just need to remember it may not be complete and to do their best to create situation where the patient shares everything with them. This includes not just past medical history, but also an understanding of which side effects need to be reported. Patients may not want to seem like they’re complaining or feel like they have to just “deal with it” because they were told a reaction might occur.
Ultimately, we will reach a point where we can reduce the number of adverse reactions — through research and education. Having more detailed data and systems that can intelligently process the data will help. Until then, we need to keep doing what we’re doing and press our vendors for ways to better store and categorize data.
Marsha K. Millonig, MBA, BPharm, is president and CEO of Catalyst Enterprises, LLC, and an Associate Fellow at the University of Minnesota College of Pharmacy’s Center for Leading Healthcare Change.
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