Cambridge, MA-based Biogen Inc. saw its stock price fall after slashing its guidance outlook for the rest of the year in its second quarter earnings report. The company said it received FDA approval to make its multiple schlerosis drug at its Durham plant.

In its earnings report, Biogen reported record Q2 earnings of $4.22 a share, up 21 percent from the same period last year. It had revenues of $2.6 billion.

It lowered its outlook, however, on revised expectations for sales of the MS drug Tercfidera, which it will make in the RTP. The company lowered its guidance from an expected $15.45 a share to $15.85 a share in earnings.

Shares fell 11.7 percent before the market opened Friday morning. It traded between $325 and $319 and change mid-morning Friday, down about 16 percent on higher than average volume.

Although Tecfidera sales have powered Biogen success, sales have slowed. While Tecfidera produced about $883 million in revenue, up 26 percent form $700 million in the same period last year, the growth rate fell from the 63 percent of the first quarter.

The company says Terfidera has seen “moderated patient growth following rapid uptake.”

Biogen also noted that it lowered the sale price of the drug in Germany following its disclosure that a patient taking Tecfidera died from a rare brain infection. In November, the FDA issued a warning about the death.

The company did release good news this week. On Wednesday, it released data suggesting its experimental Alzheimer’s drug aducanumab, the first batches made in its Durham plant, slowed the progress of the disease. It is now recruiting for two late stage clinical trials of the drug.

CEO George Scangos said the drug “has a potentially transformational opportunity for Biogen.”