Grant: Project Grant

Millions of Canadians take prescription medicines every day. Sometimes, one drug can influence the effect of another, leading either to drug toxicity or loss of effectiveness as the result of a "drug-drug interaction" (DDI). Most of what is known about DDIs comes from two types of studies: case reports describing new or unusual DDIs, and volunteer studies describing what happens when two drugs are taken together, usually by young, healthy volunteers. Studies like these can be informative, but they provide little insight into what happens in real-world practice, especially in older patients who take multiple medications or have other health problems. In this grant, we propose a series of studies that will generate new insights regarding the consequences of DDIs in real-world practice. To do this, we will link multiple large healthcare databases (prescription claims, laboratory tests, hospital visits, mortality statistics, physicians' services and others) over a period of more than 20 years. Some of the questions we plan to answer include: 1. When certain antibiotics are combined with widely-used drugs for heart disease and diabetes, what factors increase the risk of dangerously high potassium levels or sudden death? 2. Does a new class of diabetes medications increase the risk of muscle damage in patients taking cholesterol-lowering drugs? 3. Do various medications cause dangerously low heart rates in people taking drugs for heart disease or dementia? 4. In patients taking diuretics (a.k.a. "water pills"), do some antidepressants but not others predispose to sudden death? 5. Does receiving prescriptions from different pharmacies place patients at risk of harm from DDIs? Our team consists of clinicians and scientists with extensive experience in the conduct of this kind of research. The studies proposed in the application are novel, feasible in few research institutes worldwide, and relevant to the health of millions of people in Canada and abroad.