Investors gobbled up millions of shares of a skyrocketing drug stock Friday issued by a Radford firm just approved to launch its first drug.

A close reading of recent public statements showed that executives of New River Pharmaceuticals received not quite everything they wanted in a regulatory decision late Friday. Validation of the company's technology and first product were there. Yet it wasn't the grand slam it would have been had regulators classified the drug as having a low risk of abuse and addiction.

Still, investors opened their wallets.

Shares of New River Pharmaceuticals stock climbed nearly 61 percent Monday, trouncing all other U.S. biotechnology securities in terms of one-day gain, Yahoo Finance said.

The trading volume surged to 11.8 million shares, more than 20 times normal. Off-hours buying and selling that began during the weekend wasn't even in that count.

Well-timed investments produced fast cash. A last-minute investor who bought 100 shares at Friday's closing price would have been about $2,000 richer on paper by late Monday afternoon. And cashing in was no problem because investors were still buying on hopes the rally will continue.

On Friday, the Food and Drug Administration issued an "approval letter" to New River for a stimulant that moderates attention-deficit hyperactivity disorder. The ruling said the drug can be approved for sale to children age 6 through 12 after the government sets restrictions for public health and safety. That means the regulatory process won't end until after further proceedings before the Drug Enforcement Administration, a process that could take a few months.

This is an important caveat.

Here's why: The federal government controls the public's access to abusable drugs to thwart recreational drug users seeking a pharmacological high. Highly abusable, addictive drugs such as LSD, cocaine and heroin are illegal. You can go to prison for having them. The government assigns them a Schedule I classification.

Schedule II drugs, including existing stimulants prescribed for ADHD, are still highly abusable but physicians can prescribe them because they're medically beneficial.

Restrictions are significant. A patient taking a Schedule II drug has to visit his or her doctor each month for a new prescription, because automatic refills aren't allowed.

By comparison, a doctor can prescribe a lower-risk Schedule III drug with five refills -- adding to its convenience. Schedule IV drugs are even more readily available.

New River wants a low-risk classification such as III or IV for its drug, based on its filings with the U.S. Securities and Exchange Commission. It's worth a $300 million milestone payment from its business partner, English drugmaker Shire, according to their partnership agreement.

But Friday, the FDA staff recommended Schedule II, according to New River's news release.

About 90 percent of the time, the DEA adapts the FDA recommendation, said analyst Robert Uhl with Friedman, Billings, Ramsey Group Inc.

Uhl said the FDA is risk-averse these days, in spite of New River producing hard evidence that its compound isn't likely to become a street drug of choice. Addicts who mainlined New River's drug in controlled studies told researchers they didn't like it all that much because the high didn't really kick in for two or three hours and wasn't highly enjoyable, Uhl said.

Even though the FDA wasn't persuaded enough to grant physicians prescribing leeway, it's still a better drug than what's already on the market, according to Uhl.

For such a drug, ideal performance is a steady, stimulated state that lasts all day and wears off in the evening so the patient can sleep. Uhl said New River's beat market leader Adderall XR in a comparison of the steadiness of effect.

Overall, the FDA decision validates the company's drugmaking technology and its first product, Uhl said. In fact, investors who had placed "short" bets expecting the stock to drop Friday or today had to backpedal when New River received good news. To close out their accounts, they joined profit-seekers in buying shares Monday, stimulating demand, Uhl said.

R.J. Kirk, chief executive officer of New River, said the drug still could earn a less-restrictive classification during upcoming DEA proceedings but could become commercially successful without it.

"We're pleased and delighted and very proud of what our team has accomplished," he said.

Asked if he felt any disappointment, Kirk said "none whatsoever."

A Roanoke County woman who owns the stock was overjoyed.

Terri Ferguson, a Roanoke County resident who works in health care, said she could sell her holdings right now and triple her investment. But she is holding her shares. "It's just an excellent opportunity," she said.

Robert Roy, president of the Radford Chamber of Commerce, said New River is a welcome corporate citizen in Radford. He said the community is excited about "the potential limelight of just having our name in the national and international community as the home of this company."