Amgen Inc. faces a new type of competition with the launch of Zarxio, the first biosimilar drug approved for sale in the U.S.

The Thousand Oaks biotech tried to delay the introduction of Zarxio with an injunction, but a court denied the motion Wednesday. The Food and Drug Administration approved Zarxio in March. Amgen sued to block the launch and an appeals court ruled in July that Novartis, the Swiss maker of Zarxio, could sell the product starting on Wednesday.

Both Zarxio and Neupogen help chemotherapy patients fight infections by increasing white blood cell counts.

Biosimilars are medicines that copy proprietary biotech drugs when patent protection expires. Because small differences in the environment or manufacturing processes may alter the final product, the drugs are called similar – but not identical – to the original drug. Neupogen’s patent expired last year.

Novartis also announced that the wholesale list price for a 300 microgram syringe of Zarxio is $275.66, about 15 percent less than the cost of Neupogen, although specific sales prices will vary depending on volume and other factors.

Shares of Amgen closed down $3.06 or 2 percent to $149.23 on the Nasdaq.