Drug Interactions : A Method to the Madness

Having an awareness of drug interactions is more important today than ever before. The aging population requires multiple medications as new guidelines recommend the use of multiple classes of medication to protect these patients. As an example of polypharmacy, look at patients’ post-myocardial infarction (MI). They should be taking antiplatelet therapy, a statin, angiotensin-converting enzyme (ACE) inhibitor, and beta blocker. This quadruple therapy forms the basis of state-ofthe-art treatment. We are constantly trying to treat patients earlier, meaning they will need multiple therapies for longer durations. With this new found polypharmacy philosophy comes the risk of drug interactions (DI). In fact, physicians today need to not only know about all the prescribed drugs a patient is taking, but also all the herbal medications they may be using as well. Many cardiac patients are on at least four or five medications. It has been estimated that the risk of DI can increase from 6% in patients taking two medications, to 50% with five medications, and 100% with up to 10 medications.1 In order to avoid interactions, it is important to review some basic concepts in pharmacology. Peter Lin, MD, CCFP With many cardiac patients taking at least four or five medications, drug interactions are bound to occur. To ensure patient well-being, it is paramount to understand medications and predict interactions before they occur. Dr. Lin lends a hand by reviewing the underlying mechanisms behind drug interactions.