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Shares of

AMAG Pharmaceuticals

(AMAG) - Get Report

fell Tuesday after the company said that unresolved manufacturing issues contributed to a


in the approval of its injectable iron replacement therapy.

AMAG Pharmaceuticals said it had received a second complete response letter from the U.S. Food and Drug Administration, ahead of the agency's expected Dec. 30 approval decision date.

The company is seeking FDA approval for ferumoxytol, now known by its brand name Feraheme, as a treatment for iron-deficiency anemia in patients with chronic kidney disease.

AMAG Pharmaceuticals shares were down 12 cents, or 0.4%, to $33.95 in recent trading.

Clearly the Feraheme approval delay is a disappointment, and so weakness in AMAG Pharmaceuticals shares today isn't a surprise. However, the news could have been far worse. While manufacturing issues with Feraheme continue to hold up approval, the company said the FDA didn't raise any new issues or concerns in the second complete response letter.

On a conference call Tuesday morning, AMAG Pharmaceuticals CEO Brian Pereira said rather explicitly that the rate-limiting step on Feraheme's approval is the FDA sign off on all the remedial steps and plans submitted by the company to address the Feraheme manufacturing issues.

The company submitted these new manufacturing plans to the FDA in October after the receipt of the first complete response letter. It's simply taking more time than anticipated for the FDA to go through AMAG Pharamceuticals' response, Pereira said.

Most important, there have not been any new issues or problems with Feraheme's manufacturing since the FDA's previous inspection of the company's Cambridge, Mass., facility.

Also good news: Pereira says the company is pleased with ongoing Feraheme labeling discussions and that there hasn't been any discussion regarding a split label that would separate kidney disease patients on or off dialysis.

Pereira would not reiterate previous guidance for a first-quarter 2009 launch of Feraheme, which is why I'm assuming that the final FDA approval may take a bit longer than anticipated. A second-quarter approval and launch would allow for FDA re-inspection of the Feraheme manufacturing plant, if necessary.

JP Morgan analyst Matt Roden, commenting Tuesday morning, likened AMAG Pharmaceuticals' travails to those



experienced when it was seeking FDA approval for its ADHD drug Vyvanse in 2007. Shire also went through two complete response letters and had to resolve labeling and manufacturing questions over the course of six months before getting FDA sign-off for Vyvanse.

If that's the case for AMAG Pharmaceuticals, too, it should be no harm, no foul, and the stock price should recover and rise dramatically. What I don't want to see is a situation akin to

Discovery Labs


, which has tried and failed repeatedly across several delays and FDA complete response letters, to get approval for its premature infant lung drug Surfaxin.

If AMAG Pharmaceuticals turns into another Discovery Labs, there will be serious problems. At this point, however, I'm confident the company's not heading down that rocky road.

Adam Feuerstein writes regularly for TheStreet.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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