5. Glenmark Pharmaceuticals

2011 generic drug sales: $778 million
Growth rate 2011: 37%
Growth rate 2010: 17%

Glenmark Pharmaceuticals is among the biggest drugmakers in India, but its high-octane growth isn't a domestic product. You don't more than double your generic sales in the space of a year by depending on the fragmented, low-priced Indian market. No, Glenmark's most powerful engines are in the U.S. and Europe, where blockbuster brands are going off patent, opening up multibillion-dollar markets to copycat drugmakers.

The company's U.S. generics business alone grew 45% during its last fiscal year, surpassing $250 million for the first time. The company won FDA approval for 14 generic products and launched 12 of them, including exclusives in dermatology, one of Glenmark's burgeoning specialties. The company has also been focusing on the U.S. contraceptives market, with 10 FDA-approved products and four more awaiting approval.

The birth-control pills business is one example of how quickly Glenmark can move. The company launched its first U.S. contraceptive pill just two years ago. But it's also an example of the pitfalls of fast growth; earlier this year, Glenmark joined several other drugmakers in pulling batches of mispackaged contraceptive pills.

Last year's European generics sales grew at double the pace as those in the U.S. The company plans to continue building up its business there, focusing on the U.K., Germany and the Netherlands. Another growth area is active pharmaceutical ingredients, which Glenmark aims to make a bigger percentage of its overall generics sales. The company is also focusing on emerging markets outside India, such as Russia and Eastern Europe, anticipating that growth there will continue even as the flow of new blockbusters tapers off in the U.S. after 2015.

5. Glenmark Pharmaceuticals