How do the 12 priciest drugs in the U.S. stack up?

Last week, Vertex Pharmaceuticals ($VRTX) got FDA approval for Kalydeco, the first cystic fibrosis drug to address the disease's cause, rather than just its symptoms. The price tag: $294,000. But as observers pointed out at the time, that's not as expensive as it gets. Today's drugs for debilitating and rare diseases command 6 figures almost as a matter of course. Medical Billing & Coding's blog reminds us just how much--and shows where Kalydeco ranks.

Of the 11 most expensive drugs in the U.S., Kalydeco would come in 8th, between Genzyme's Myozyme treatment for Pompe disease, which runs $300,000 a year for an adult, and Regeneron's ($REGN) Arcalyst, for genetic inflammatory disorders, at $250,000 a year. Like virtually every pricey drug on the list, these two are targeted to small populations with life-threatening illnesses--and probably wouldn't exist without the FDA's orphan-drug designation.

Topping the list is the notoriously expensive Soliris, a $409,500 drug used to treat a rare blood disease, paroxysmal nocturnal hemoglobinuria. About 8,000 people in the U.S. have the disease, so the most Alexion Pharmaceuticals ($ALXN) could hope to bring in from Soliris in the U.S. is about $3.2 billion; its 2010 sales had reached $541 million.

Shire's Hunter syndrome drug Elaprase comes in second at $375,000 per year (as Medical Billing & Coding says, some estimates put the actual price of Elaprase therapy, at $4,215 per vial, much higher than that). Third? Naglazyme, a treatment for the metabolic condition Maroteaux-Lamy syndrome. The BioMarin ($BMRN) drug runs $365,000 per year. We'll let you check the list for the rest.

- see the Medical Billing & Coding blog post