Most drugmakers don't have the clout to get Congress fighting for their compounds, but apparently Amgen's (NASDAQ:AMGN) increased spending on lobbyists is paying off. The Associated Press reported yesterday that the Senate passed a resolution calling for the reversal of strict reimbursement rules by the Centers for Medicare and Medicaid Services (CMMS) on Amgen's lead drugs.

It has been a long year for Amgen and its two anemia-treating compounds, Epogen and Aranesp. First, a Danish study came out showing Aranesp did not improve quality of life or reduce the risk of blood transfusions for those with noncancer-related anemia. This put a serious dent in Amgen's plans to expand the use of Aranesp, and sales of the drug fell 10% year over year in the second quarter.

Shortly thereafter, the FDA slapped a stronger black box safety warning on Amgen's two  anemia compounds as well as Johnson and Johnson's (NYSE:JNJ) anemia-treating Procrit. The final nail in Amgen's erythropoiesis-stimulating agents (ESA) growth plans came in July when the CMMS enacted stricter reimbursement rules for the ESA drug class that would curtail some usage in patients reliant on these government insurance programs.

Amgen has argued that the CMMS reimbursement rules are unduly strict and don't follow clinical practice guidelines from leading doctors groups such as the American Society of Hematology. The CMMS and Amgen have been going back and forth on reimbursement rules for the ESAs for years.

Together, Aranesp and Epogen accounted for 44% of Amgen's sales in the latest quarter, but times have been tough for Amgen's top two compounds. In Europe, no fewer than three new competing agents will be muscling these drugs for market share by the end of next year, including Shire's (NASDAQ:SHPGY) Dynepo, Novartis' (NYSE:NVS) biosimilar Epogen and Roche's Micera.

Amgen will get another chance to argue its case to the FDA about the risks and benefits of its ESA drugs next week during an FDA advisory committee meeting. The agency will take the recommendations from this meeting into consideration in developing new treatment guidelines for the ESAs, so Amgen could be in for one more kick in the tail this year.

Looking for more Foolish drug stock coverage? Check out the Fool's market-beating Rule Breakers newsletter. You can check out all our recommendations with a 30-day free trial.

Fool contributor Brian Lawler does not own shares of any company mentioned in this article. Johnson & Johnson is a Motley Fool Income Investor selection. The Fool transfuses an A+ disclosure policy.