Grant: Project Grant

Smoking is the leading cause of preventable death in Canada, linked to cancer, heart disease, stroke, and many other serious illnesses. While many people who smoke want to quit, most existing treatments have only modest long-term success and many people gain weight after they quit increasing their risk of diabetes. New and more effective approaches are urgently needed that not only are better but also improve overall health. Our study will test whether a medication called tirzepatide can help people quit smoking and improve their overall health. Tirzepatide is already approved in Canada and the U.S. to treat diabetes and obesity. It works by changing signals in the body that control appetite, cravings, and metabolism. Early research suggests that these same effects may also help reduce the urge to smoke. In addition, because people who smoke often have higher risks for heart disease and other metabolic problems, tirzepatide's benefits for weight, blood sugar, and cholesterol could further improve long-term health. We will invite 164 adults who smoke and are living with obesity or are overweight to take part in this study at the Centre for Addiction and Mental Health (CAMH) in Toronto and the Ottawa Heart Research Institute in Ottawa. People will be randomly assigned to receive either tirzepatide or a placebo (inactive substance) for 24 weeks. Everyone will also receive standard quitting support to provide motivation and strategies to quit for good. We will track quit rates, cravings, weight, and other health measures during and after treatment 6 months after they try to quit and 4 weeks after they stop the medications. If tirzepatide helps more people quit smoking, prevents weight gain & improves heart & metabolic health, it could lead to a new treatment option that saves lives. This would benefit not only individuals but also the health system by preventing smoking-related illnesses and reducing healthcare costs.