"Erythropoietin (EPO) is a hormone that stimulates red blood cell production in the bone marrow. It is also a medication, often referred to as an erythropoiesis-stimulating agent (ESA), used to treat anemia, particularly in patients with chronic kidney disease (CKD). Synthetic EPO, or recombinant human erythropoietin (rEPO), is also used by some athletes to enhance performance, a practice known as blood"

I had not heard of it. I think I heard that some would sleep in a hypobaric chamber, which would increase RBC count(?), then they'd withdraw the blood, and transfuse it in the future. I have no idea how true any of that is, or the other history of drug abuse in the sport. I guess data collection is so good now, that there is a large fan analysis of rider power output, which helps in spotting outliers.

I got almost the same here: 9907 and 4th best score!

Well it works on the cardiovascular system & is widely known for that. Not the worst guess among an unknown initialism

Nitroglycerin has been used in medicine for over 100 years, as long as it's diluted enough there's zero chance of it exploding.

I actually guessed it. And I'm a medical student for the record. I chose it because Nitroglycerin has a very rapid onset of action which I thought would have made more sense for races. EPO is much more of a chronic treatment, it takes weeks to act.