So, it's not just a potential "side effect" ~ you can induce a heart attack simply switching from one drug to the other.
I am a physician. I'd say your friend had underlying coronary artery disease and bad luck if he had a myocardial infarction. The timing was an untimely co-incidence.
If he had an episode of congestive heart failure, which is not the same diagnosis, that was probably due to just the Avandia. Avandia interacts with a number of other drugs, but the only adverse effect that I would expect the combination of Avandia and metformin is hypoglycemia. I would be wary of what I find on the internet. I just scanned rosiglitazone and metformin, adverse effects on PubMed. You're welcome to see what I missed.
Doc,
What do you think about the cinnamon "therapy"? Does it sound safe and/or reasonable to try?
Heart Attack Patient Dies In ER Waiting Room- Ruled a Homicide
Patients with painless Acute Coronary Syndrome tended to be older, were more often women, and more often had diabetes and prior heart attacks. It may be that prior heart damage impairs pain perception due to disruption of sensory receptors, and that diabetes impairs pain perception, suggests Harry P. Selker, M.D., M.S.P.H., of the Tufts-New England Medical Center.
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Just went to the manufacturer's reports ~ that's always the best source.