The drug approvals keep coming for Gilead Sciences (Nasdaq: GILD). Yesterday, the company -- one of my favorite drug developers -- announced that it had received preliminary European Union approval of antiviral drug Viread as a treatment for hepatitis B.

Viread is already approved as a treatment for HIV and AIDS in the European Union. This positive recommendation is the first step in a drawn-out process for selling drugs in the EU. The preliminary approval in the EU always precedes the approximate 60- to 90-day wait for final approval. Then it may take a while for Gilead to get some EU countries to reimburse it for Viread's use in hepatitis B patients.

This label expansion probably isn't going to lead to big bucks for Gilead, though. There are already numerous other hepatitis B compounds on the market in the European Union, such as GlaxoSmithKline's (NYSE: GSK) Epivir and Novartis' (NYSE: NVS)  Tyzeka, which was developed by Idenix Pharmaceuticals (Nasdaq: IDIX) and is sold in Europe under the brand name Sebivo. In addition, hepatitis B is unlike other infectious diseases -- such as AIDS or hepatitis C -- in that there is a vaccine for the disease, which also reduces the market opportunity for hepatitis B drugs.

Nonetheless, every label expansion helps prolong a drug's sales life cycle, and Viread sales slowed last year. Viread sales were actually down 7% year-over-year in the fourth quarter to $148 million, as Gilead's combination HIV therapies, Truvada and Atripla (which contain Viread), sucked sales away from the standalone version of Viread.

Viread is also up for approval in the U.S. and multiple other countries around the world as a treatment for hepatitis B. While getting these label expansion approvals isn't going to dramatically change the outlook for Gilead's future, it's nice to see Gilead squeezing every ounce of sales out of its marketed drugs.

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Fool contributor Brian Lawler does not own shares of any company mentioned in this article. The Fool has an A+ disclosure policy.