Vasodilator Therapy With Isosorbide Mononitrate or Diltiazem to Reduce Vasotoxicity in Patients With Gastrointestinal Cancer Receiving Fluoropyrimidine Therapy

This phase I/II trial compares the effect of drugs that causes widening of blood vessels as a result of smooth muscle relaxation (vasodilator therapy) with isosorbide mononitrate, diltiazem or placebo to reduce vasotoxicity in patients with gastrointestinal cancer receiving fluoropyrimidine therapy. Some patients develop chest pain (possibly even a heart attack, a drop in heart function, or a rhythm abnormality) during treatment with a class of cancer drugs known as fluoropyrimidines, which include 5-Fluorouracil (5-FU) and capecitabine. These side effects are believed to be due to the development of an abnormal reactivity of the blood vessels referred to as vasospasm. Vasotoxicity is damage or toxicity inflicted upon blood vessels (vascular system), often causing dysfunction, remodeling, or narrowing (vasoconstriction). It is a broad term used to describe the detrimental effects of certain agents, such as chemotherapy drugs. Researchers want to evaluate how often the reactivity of blood vessels becomes abnormal, during the treatment with 5-FU or capecitabine and how clinically relevant and controllable/preventable this phenomenon is in patients with gastrointestinal cancer.