Shire Shrugged Off

The company's new ADHD drug isn't necessarily better than the one it already sells.
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In a perfect world, when two drugs compete for patients with the same disease, the better drug should win out.

But "better" can be defined in many ways: A drug may be more effective than its competitor, it might be safer, easier to tolerate or less expensive.

But here's a news flash: Drug companies and the health care system don't operate in a perfect world, which is why

Shire Pharmaceuticals

(SHPGY)

will probably succeed in getting doctors to prescribe its newly approved drug, Vyvanse, for attention deficit hyperactivity disorder (ADHD).

Shire will likely accomplish this feat even though its current ADHD drug, Adderall XR, is in most ways equal to or better than Vyvanse.

It shouldn't work out that way, but it will. U.K.-based Shire is in the process of buying

New River Pharmaceuticals

(NRPH)

, which developed Vyvanse. Once that deal closes, Shire will control both Adderall XR and Vyvanse.

The thing to remember here is that Adderall XR will go generic in a couple of years, so Shire needs to get patients off that drug and onto Vyvanse, which has years and years of profitable patent life left.

And because Shire will control both drugs -- and is the dominant player in the ADHD market -- the company can pretty much do whatever it takes to make the switch happen. Shire sales reps will descend on doctors' offices to push Vyvanse, while minimizing Adderall XR. The drug might be priced at a discount while Adderall XR's price rises.

And would anyone be surprised if we see supply shortages of Adderall XR in the market, making the drug hard to prescribe and tilting the playing field in Vyvanse's favor?

The market certainly believes that Vyvanse will be a success. New River's stock has been a rocket, and generally, investors cheered when Shire announced the deal to buy the company. American depositary shares of Shire closed Thursday down 2.3% to $62.97.

But I'm a bit of an idealist, and this still has me believing (this is going to sound naive) that the best drug should win. And when I look at Adderall XR vs. Vyvanse, I can't see any good reason why a doctor would prescribe the latter.

Take a look at the chart, which breaks down the common adverse events listed for each drug, as listed in their respective labels filed with the Food and Drug Administration (which can be found

here

). As you can see, Adderall XR is better tolerated than Vyvanse across all but one category.

According to the same drug labels, 10% of Vyvanse-treated patients in clinical trials discontinued due to adverse events deemed related to the drug. For Adderall XR, the drug-related discontinuation rate in studies never exceeded 3.4%

But does Vyvanse work better against ADHD than Adderall XR? No. The efficacy of both drugs is entirely comparable.

Check out this

poster

summarizing results from a phase II study in 52 kids, comparing Vyvanse (referred to here as lisdexamfetamine) with comparable doses of Adderall XR (referred to as mixed amphetamine salts extended release, or MAS XR) and placebo. This study was presented at the 53rd annual meeting of the American Academy of Child and Adolescent Psychiatry on Oct. 28, 2006.

The study's authors concluded that: 1) "Lisdexamfetamine

Vyvanse, an amphetamine prodrug, has comparable efficacy to MAS XR

Adderall XR in the treatment of ADHD school-aged children;" and 2) "Both lisdexamfetamine and MAS XR treatment led to similar significant improvements in efficacy compared with placebo."

Stated simply: Vyvanse and Adderall XR both work equally well in ADHD patients.

The Vyvanse label, by the way, describes this study but omits any mention of the drug's equivalence to Adderall XR. Instead, it only discusses Vyvanse's superior efficacy compared with placebo.

When New River was developing Vyvanse, the company touted technology that was supposed to make Vyvanse resistant to abuse (setting it apart from Adderall XR) and therefore more likely to receive preferred scheduling from the Drug Enforcement Agency.

But that didn't happen. Both Adderall XR and Vyvanse are classified as Schedule II drugs, which means the government considers both drugs to have a "high potential for abuse." Doctors may prescribe only a 30-day supply with no refills.

The FDA did allow Shire and New River to insert language into the Vyvanse label describing studies that show the drug to have abuse-resistant qualities. Publicly, the companies have described this as the "abuse-related drug liking characteristics of Vyvanse, which illustrate benefits that differentiate this compound from other ADHD medicines."

And indeed, when you read the Vyvanse label, it does mention that when drug addicts recruited for a study were given a 100-milligram dose to play with (higher than what would normally be prescribed to a child), the "high" they received was less than what they got when given a dose of Adderall.

This is science, so drug addicts don't get high. Instead, they report responses on scales that measure "drug liking," "euphoria," "amphetamine effects," and "benzadrine effects."

But what happens when a drug addict takes just a bit more Vyvanse, like 150 mg of the drug? The label tells us:

"However, oral administration of 150 mg lisdexamfetamine

Vyvanse produced increases in positive subjective responses on these scales that were statistically indistinguishable from the positive subjective responses produced by 40 mg of oral immediate-release d-amphetamine and 200 mg of diethylpropion."

Translation: You can abuse Vyvanse, you just might need to swallow two pills instead of one.

You can see where I'm going with all these comparisons. Adderall XR is a perfectly good drug for ADHD that just happens to be losing patent protection. Therefore, Shire needed to find a replacement to keep the profit flowing. With New River and Vyvanse, Shire found just what it was looking for.

Never mind that Adderall XR is probably better for patients. That's perfect-world stuff. In the real world, where drug companies play and patients pay, shiny new patents are what matter most.

Adam Feuerstein writes regularly for RealMoney.com. In keeping with TSC's editorial policy, he doesn't own or short individual stocks, although he owns stock in TheStreet.com. He also doesn't invest in hedge funds or other private investment partnerships. Feuerstein appreciates your feedback;

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