For more than a decade, the top-selling Novartis product has been a drug called Diovan. It’s an anti-hypertensive, which means that it treats high blood pressure, and patients who need it take the medicine every day. Scientists inside our company spent many years developing Diovan, and it has been tested on thousands of patients in clinical trials. Altogether Novartis spent well over a billion dollars on development and received a patent to sell Diovan exclusively for 14 years. When I joined Novartis, in 2007, our entire pharmaceuticals division had revenue of about $24 billion, and Diovan accounted for $5 billion of that.

A version of this article appeared in the December 2012 issue of Harvard Business Review.