Amidst a sea of market red, a pair of biotechnology stocks -- American Pharmaceuticals Partners (NASDAQ:APPX) and Amgen (NASDAQ:AMGN) -- are up on favorable drug news.

American Pharma sells more than 100 different drugs, most of them injectible generics targeting cancer and anti-infective markets. After gaining last week on speculation, today the stock is up another 10% on news the company received U.S. Food and Drug Administration (FDA) approval for Piperacillin, the generic equivalent of Wyeth's (NYSE:WYE) Pipracil. The generic drug is a third-generation antibiotic for serious infections.

Wyeth discontinued production of Pipracil in 2002, causing hospitals and doctors to switch to Wyeth's newer Zosyn, which has broader anti-infective applications. American Pharma's Piperacillin will give hospitals the choice of returning to a Pipracil bio-equivalent drug that, American claims, can be a more suitable and targeted treatment. Combination antibiotics such as Zosyn can raise concerns about increasing bacterial resistance.

Zosyn, with $257 million in 2002 sales, should top $350 million in 2003. American Pharma expects to be the sole provider of generic Pipracil for some time, taking a piece of Zosyn's sales. For a company with $300 million in annual revenue, it could see considerable gains from the drug next year.

Piperacillen is the sixth Abbreviated New Drug Application (ANDA) the company has had approved this year. It has about four dozen others in development, and approval -- when it comes -- is much quicker for generics than for novel drugs, making American Pharma a company worth watching.

Amgen's novel drug
The world's largest biotech company also had good news, sharing on Sunday that phase III trials of its cinacalcet HCI were successful and that the drug, a treatment for illness associated with chronic kidney disease, received priority review status from the FDA. As The Motley Fool reported on Friday, the drug was expected to have a positive review and the news is significant for Amgen.

In separate but related news, Amgen announced study results suggesting its blockbuster drug Aranesp may be administered once monthly to patients with chronic kidney disease and anemia. Administering a drug less frequently is an obvious plus for a patient, less expensive for hospitals, and can improve a drug's competitive position -- in Amgen's case, relative to competitors like Johnson & Johnson (NYSE:JNJ).

Amgen's stock is richly priced for a reason, but investors with patience may wait for buying opportunities, such as were available early this year. Half of successful investing is buying at a price that affords market-beating success.

Don't know your cinacalcet from your Aranesp, or your Piperacillin from your Pipracil? Join the Fool Community to hear of and track changes in the world of biotechnology. Knowledge can make you money. Jeff Fischer holds shares in J&J.