I've written about drug-drug interactions before. In a letter to the New England Journal of Medicine, doctors from the Dana-Farber Cancer Institute describe their findings of an interaction between aspirin and androgen suppression therapy used for treating prostate cancer. They re-analyzed data from a study they had completed (and published) of over 200 men with localized prostate cancer, half of whom were treated with flutamide, an androgen-suppressor. Six months of flutamide was associated with increased 5-year survival (88%, vs. 78% for those not given flutamide). Those men also taking baby aspirin (~81 mg daily) developed raised liver function test results during the study, causing 37% of the flutamide patients to discontinue the drug early, something only seen in 13% of the non-aspirin users. And early discontinuation of flutamide was linked with increased 5-year mortality.

Aspirin in high doses has been shown to produce abnormal liver function test results in some patients, and the breakdown (removal) of aspirin is slower in patients with low testosterone levels. So the findings in this study are not surprising. But they represent a good example of a drug-drug interaction, and everyone who takes more than one drug should be alert. Your pharmacist can help you!