As they pursue home run products, drugmakers also seek the pharmaceutical equivalents of a baseball utility infielder -- a compound that works on several diseases or conditions.

Few companies can produce sluggers like Pfizer's (NYSE:PFE) Lipitor, but they can still field a decent lineup with drugs that can play several positions and hit a lot of revenue singles and doubles. By getting regulatory approval for several uses, a single compound can be marketed in multiple ways, generating that magical $1 billion "blockbuster" revenue home run.

Pfizer, Wyeth (NYSE:WYE), and Eli Lilly (NYSE:LLY) have pursued this strategy with selective estrogen receptor modulators, or SERMs, in women's health. They want to replicate the success of Lilly's Evista, which still produces $1 billion a year, but unfortunately, their success rate has been low.

They have SERMS to treat osteoporosis, invasive breast cancer, vaginal atrophy, and/or postmenopausal symptoms. However, SERMs have been hit with U.S. regulatory delays or rejections and clinical trial disappointments, although some recently won European Union support.

Bone drug blues
Lilly just walked away from the SERM arzoxifene, which had been targeted for osteoporosis and invasive breast cancer. Although arzoxifene met the main research goals in a late-stage clinical trial, Lilly won't submit it to the Food and Drug Administration. It cited the drug's side effects and "currently available treatments, including Lilly's own osteoporosis products." Probably not a bad call because, as Fool contributor Brian Orelli pointed out, arzoxifene would have had to compete in a crowded osteoporosis market filled with non-SERM drugs such as Boniva from GlaxoSmithKline (NYSE:GSK) and Roche.

Arzoxifene had been viewed as a successor to Lilly's Evista, which has been approved for both preventing and treating osteoporosis and for reducing the risk of invasive breast cancer in postmenopausal women.

The reason arzoxifene was important is that Evista faces a patent challenge from Teva Pharmaceutical Industries (NASDAQ:TEVA). However, in April, Lilly won a temporary restraining order from a federal court preventing Teva from selling a generic until the case is resolved.

Long delays and rejections
The recent arzoxifene saga was brief compared to Pfizer's long-running struggle with lasofoxifene. The FDA rejected it in 2005 for prevention of osteoporosis and again early this year as a treatment for osteoporosis. It's also been rejected for treating vaginal atrophy, according to Ligand Pharmaceuticals (NASDAQ:LGND), which partners with Pfizer on the drug.

On the plus side, the European Union endorsed the drug in March for treating osteoporosis in postmenopausal women with an increased risk of bone fracture.

Ironically, Wyeth is partnered with Ligand on another SERM called bazedoxifene. Wyeth filed prevention and treatment of osteoporosis applications with the FDA in 2006 and 2007. However, it has been requested to provide more information, which it expects to do this year. Meanwhile, the EU has recently permitted the sale of bazedoxifene as a treatment for osteoporosis.

Long-term prospects for SERMs
In theory, there would be a big market for a new type of SERM that would have fewer side effects than what's on the market. Evista, for example, contains the FDA's strict "black box" warning on its label about the risk of death from stroke. But the above stories indicate the difficulty in getting such drugs to market.

One outside-the-box possibility is being pursued by small biotech GTx (NASDAQ:GTXI). It sells an old SERM called Fareston as a breast cancer treatment. More importantly, it is trying to use the key ingredient in different dosage strengths for men's health. One version in late-stage testing is for preventing prostate cancer in certain high-risk men. GTx and its partner, Merck, are also looking at a midstage trial for a SARM, a selective androgen receptor modulator, to treat muscle loss in patients suffering chronic obstructive pulmonary disease.

To sum up, investors looking at a small-market team like GTx or a big-market team like Pfizer need to scout compounds with the potential for multiple uses. In drug R&D, as in baseball, you never know when you'll find a star like Evista, or a disappointment like arzoxifene.

Where else to make money in Pharma:

Fool contributor Robert Steyer doesn't own shares of any companies cited in this story. Pfizer is an Inside Value recommendation. The Fool has a disclosure policy.