New River Pharmaceuticals Inc., a small Radford drug company that has yet to release a product, is set to be acquired for $2.6 billion by Shire plc, an English company with which it has been working since January 2005.

Based on share value, more than $1.46 billion of that cash payment would go to Randal J. Kirk, New River's founder, chairman, chief executive officer, largest shareholder, and a resident of the Belspring section of Pulaski County.

That would bring Kirk's net worth to approximately $2 billion.

Shire's interest in New River centers on the latter's Vyvanse, a stimulant developed to treat attention deficit hyperactivity disorder, but with less potential for abuse than current medications. The FDA is expected to issue its final approval for Vyvanse Friday.

Under the terms of the deal -- subject to approval by Shire's shareholders and the Securities and Exchange Commission -- the company will pay $64 a share in cash, about 12 percent above the New River share price at the close of the market Friday.

With its local headquarters and 46-person work force, New River Pharmaceuticals is one of the region's major entrepreneurial success stories. After an initial public offering in 2004, the company's stock rose more than 470 percent during the next year.

"Part of the significance of this thing's story around here," according to Ray Smoot, chief operating officer of the Virginia Tech Foundation, "is it gives credibility to the region as a place where a company can come to market and experience great appreciation."

According to analysts, that appreciation could make New River profitable for the first time. In October, the company reported a quarterly loss of $13.6 million, while liabilities exceeded assets by $64.7 million.

But Andrew Forman, an analyst with WR Hambrecht & Co., the San Francisco investment bank that took New River public in 2004, forecasts that Vyvanse will be a blockbuster, bringing in revenue of $244 million in 2007 and almost $1.2 billion in 2009.

New River had entered into an agreement with Shire in January 2005 in which the companies would jointly market and distribute Vyvanse. Shire agreed to pay New River $500 million for a piece of the action -- it has made $100 million in payments already, but if the buyout goes through, the rest of the agreement will be moot.

Shire's flagship product is Adderall, also a stimulant prescribed for ADHD and the leader in the $2 billion ADHD-drug market begun in the 1960s with Ciba's Ritalin. (The company is now part of Novartis International.)

Shire hopes Vyvanse can replace Adderall as the first of a new generation of treatments for ADHD.

That's because Vyvanse takes one of the main ingredients in Adderall -- dextroamphetamine -- and uses New River's "Carrierwave" technology to wrap it in a chemical that only comes off in the digestive tract. That means it can't be snorted, as can Ritalin around which a black market has formed.

Tests also show that, unlike some other stimulants, Vyvanse's chemical structure makes it safer from potential overdosing, New River Pharma has said.

Because of their potential for abuse, Adderall, Ritalin and their kin are strictly controlled, forcing patients to refill their prescriptions monthly.

If the FDA decides that Vyvanse is less of a threat, the drug could be regulated more loosely, on par with "mild" drugs such as Valium. That would reduce both the cost and burden of frequent refills. Thus Vyvanse -- and Shire -- could gain a significant advantage in the booming ADHD market.

Last October, the Food and Drug Administration tentatively approved Vyvanse for sale, pending results of additional testing.

In addition to Vyvanse, New River has two other drugs in the pipeline: one to treat hypothyroidism and one to treat acute pain. Both products will use the Carrierwave technology to reduce the possibility of abuse, which is particularly important in the case of what New River calls "NRP290," which will compete with the likes of Vicodin and Oxycodone -- two highly addictive drugs.

New River's shares closed up 8.3 percent at $63.19 Tuesday after heavy trading on Nasdaq.

"It's very good for investors, but I hate to see our little, hometown company be absorbed," said Terri Ferguson of Roanoke County, a shareholder since 2005.

Staff writers Jeff Sturgeon and Angela Manese-Lee contributed to this report.