Feb. 21--Pfizer is spending $195 million to snap up Houston-based Encysive Pharmaceuticals, a small outfit with big hopes for a breakthrough drug that, so far, the U.S. Food and Drug Administration has snubbed.

The FDA deemed as "approvable" Encysive's once-a-day pill Thelin, a drug to treat pulmonary arterial hypertension. But the federal regulator will not give its final blessing to market the drug in the U.S. until after another costly Phase III human trial.

Encysive CEO George Cole said the company doesn't have the means to fund more research. Pfizer, the largest drug maker in the world with $20 billion in cash on its balance sheet, does.

New York-based Pfizer is the force behind many of today's most popular and most commonly prescribed drugs, including Lipitor and Xanax. The company will pay $2.35 per share for Encysive, a premium of almost 120 percent over Tuesday's closing price of $1.08 per share.

The companies hope to close the deal in the second quarter of this year.

On Wednesday, Pfizer shares were up 10 cents to $22.47, and Encysive's were up $1.19 to $2.27.

In a written statement, Ian Read, Pfizer's president of worldwide pharmaceutical operations, said Encysive complements cardio-pulmonary work his researchers already are doing.

Read compared Thelin to Revatio, which Pfizer markets to treat pulmonary arterial hypertension, a disease of the arteries and blood vessels connecting the heart and lungs that can cause extremely high blood pressure.

PAH is thought to afflict between 100,000 and 200,000 people -- mostly women -- in North America and Europe, according to the companies.

While Pfizer markets Revatio to treat PAH, the same substance under the name Viagra is used to treat erectile dysfunction. Because such drugs improve blood flow, it's thought they can help constricted vessels in the heart and lungs.

According to Encysive, Thelin works in a one-two punch by blocking a chain of amino acids that constrict blood vessels and then dilating those vessels to reduce pressure inside them.

Pfizer executives wouldn't comment on whether Thelin could be marketed as an erectile dysfunction treatment in the future.

Encysive has already received marketing approval and sells Thelin in much of Europe as well as Canada and Australia.

Encysive has 75 employees in Houston and another 75 in Europe. Pfizer would not say Tuesday whether the Houston office will remain open.

The clock is ticking on the patents of many big pharmaceutical companies' drugs. Pfizer, like many other drug makers, has been buying smaller companies in the hopes that something in their research pipelines will provide a big payoff.