Final answer:
The first choice drug for treating a myocardial infarction (MI) is nitroglycerine.
Step-by-step explanation:
The first choice drug for treating a patient with a myocardial infarction (MI) is nitroglycerine. Nitroglycerine is administered sublingually (under the tongue) to facilitate absorption. It works by releasing nitric oxide, which is a known vasodilator, and endothelium-derived releasing factor, which relaxes the smooth muscle in the coronary vessels.