NEW YORK (TheStreet) -- Amgen (AMGN) - Get Report shares are down 1.42% to $157.34 in trading on Friday after the FDA gave approval to the U.S.'s first 'biosimilar' drug treatment, Novartis' (NVS) - Get Report white blood cell-boosting Zarxio.

Zarxio contains the same active ingredient as Amgen's Neupogen white blood cell treatment which logged $1.2 billion in sales worldwide last year. 

Biosimilar drugs, which have been legal in Europe for nine years, are lower-cost copies of complex drugs that based on European data tend to sell at a discount between 20% and 30% of the original biotech brand's price, according to Reuters.

Analysts at Barclays said in a note today that while the FDA's decision could affect the wider market, today's decision had widely been expected already and that Neupogen already faces competition. 

"That said, this news was expected, and Neupogen already faces competition and sales erosion from Teva's Granix (which though approved under the BLA pathway and technically a branded product, is essentially a biosimilar)," said analysts. "Nevertheless, we believe it's a matter of when, not if, the product will launch, and anticipate continued erosion of Neupogen over the foreseeable future."

TheStreet Ratings team rates AMGEN INC as a Buy with a ratings score of A-. TheStreet Ratings Team has this to say about their recommendation:

"We rate AMGEN INC (AMGN) a BUY. This is based on the convergence of positive investment measures, which should help this stock outperform the majority of stocks that we rate. The company's strengths can be seen in multiple areas, such as its solid stock price performance, growth in earnings per share, revenue growth, reasonable valuation levels and good cash flow from operations. We feel these strengths outweigh the fact that the company has had generally high debt management risk by most measures that we evaluated."

Highlights from the analysis by TheStreet Ratings Team goes as follows:

• Powered by its strong earnings growth of 26.31% and other important driving factors, this stock has surged by 30.45% over the past year, outperforming the rise in the S&P 500 Index during the same period. Regarding the stock's future course, although almost any stock can fall in a broad market decline, AMGN should continue to move higher despite the fact that it has already enjoyed a very nice gain in the past year.
• AMGEN INC has improved earnings per share by 26.3% in the most recent quarter compared to the same quarter a year ago. The company has demonstrated a pattern of positive earnings per share growth over the past two years. We feel that this trend should continue. During the past fiscal year, AMGEN INC increased its bottom line by earning $6.70 versus $6.65 in the prior year. This year, the market expects an improvement in earnings ($9.32 versus $6.70).
• The revenue growth significantly trails the industry average of 36.4%. Since the same quarter one year prior, revenues slightly increased by 6.4%. Growth in the company's revenue appears to have helped boost the earnings per share.
• Net operating cash flow has increased to $2,445.00 million or 33.24% when compared to the same quarter last year. The firm also exceeded the industry average cash flow growth rate of 2.90%.
• You can view the full analysis from the report here: AMGN Ratings Report