Pantani died of an overdose of cocaine.
As for EPO , indeed
Unable to measure EPO itself, the mandarins of international cycling at Union Cycliste Internationale (UCI) rely on a surrogate test that measures the density of cells in the blood. Blood, as you'll recall, is composed of cells -- mainly red, but also white -- and serum and other liquids that help the cells flow. A study from the 1980s, before synthetic EPO, showed that bike racers' blood averaged a cellular content of 43 percent, so the UCI decreed that anybody with a level above 50 percent would be disqualified for taking EPO.
Erythropoietin (EPO) is a glycoprotein hormone composed of 166 amino acids and 4 residual sugars. It is produced in the kidneys whenever there is an increased need for red blood cells (e.g. as a result of oxygen deficiency, living at high altitudes). Passing through the circulation, EPO enters the red bone marrow where it stimulates the production of red blood cells. EPO can be produced by genetic engineering techniques and is used in medicine in renal failure. Though banned in sport, it is used primarily in endurance sports. Detecting EPO abuse in sport is difficult, and two detection methods are currently being discussed: one direct method using urine samples (advantage: direct detection of genetically manufactured EPO, detectable in urine; disadvantage: can only detect EPO use during a period of a few days) and one indirect method using blood samples (advantage: detection of blood parameters modified by EPO even several weeks after the use of EPO; disadvantage: blood tests are required, legally contestable since it involves indirect detection). Both methods are to be used simultaneously in the Summer Olympic Games in Sydney.
Some people naturally are over 50 , but they have to be monitored over a period of time to prove that, and they then can escape sanctions if they test higher than 50.