SHOT DOWN: North Korea's Jong Su Kim holds up his medal after winning the bronze in the Beijing 2008 Olympics men's 10-meter air pistol shooting competition Saturday, August 9, 2008. Kim was stripped of his two medals and expelled from the Beijing Olympics after failing a doping test, Friday August 15, 2008.
(AP Photo/Charlie Riedel)

Yesterday, North Korean Olympic shooter Kim Jong Su was stripped of silver and bronze medals after he tested positive for propranolol. The drug is prescribed for a variety of conditions, from high blood pressure to migraines.

You've heard of various doping drugs such as EPO, but why would an Olympian use propranolol? (It probably wasn't to treat a hangover, despite some myths about its use for that condition.)

For an answer, ScientificAmerican.com called cardiologist Sandeep Jauhar, author of Intern: A Doctor’s Initiation, and director of the Heart Failure Program at Long Island Jewish Hospital in New Hyde Park, N.Y. An edited transcript follows.

Tell me what propranolol is typically used for, and what it does.

Propranolol is a beta-blocker, so it blocks the action of adrenaline. Adrenaline is implicated in a number of effects on the body—high blood pressure and a fast heart beat, for example—so by blocking it, propranolol lowers blood pressure, and heart rate. Doctors often use it to treat patients with high blood pressure, and with heart disease, to keep the heart rate in a reasonable range and not tax the heart muscle, or have it use too much energy.

It’s also used to treat other conditions that are mediated by high adrenaline levels, such as tremor and performance anxiety. Beta-blockers don’t lower the anxiety level, but they lower manifestations of the anxiety, such as fast heart rate, sweating and tremor.

I understand it’s also used for treating migraines?

It is used for treating migraines in kids.

Why would an Olympics shooter want to use it?

Probably for some of the same things that I just mentioned. It’s used to combat stage fright, or performance anxiety, and tremor. From the next to nothing I know about this case, he wasn’t using it for a medical condition; it was for performance enhancement.

Doctors do prescribe it for people with tremor, for example elderly patients with essential tremor. That’s a medical condition. It sounds like the tremor this shooter was experiencing had more to do with enhanced performance than with any medical condition. So it’s reasonable to ask whether he had an unfair advantage.