The pharmaceutical landscape is rapidly changing as patents for some of the blockbuster drugs of the last decade near expiration and other players try to grab some of the remaining revenues before generic medications flood the market.

AstraZeneca (AZN) announced Thursday morning that it has filed a New Drug Application with the FDA for its antiplatelet treatment ticagrelor. The drug is meant to treat major cardiac events in patients with acute coronary syndrome (ACS), a disease that affects 2.4 million Americans according to the American Heart Association.

The drug works by keeping platelets in the blood from sticking together, which keeps them from clogging arteries. It will be called Brilinta if approved for sale by the FDA. AstraZeneca said it's now up to the FDA to determine the timeline for when the drug will potentially be approved. The Anglo-Swedish drugmaker filed for regulatory approval in Europe in October.

The submission to the FDA is based on the phase 3 Plato study done by AstraZeneca comparing Brilinta plus aspirin with Plavix plus aspirin. Results of the 18,624-patient study showed that Brilinta was more effective than Plavix in treating patients who underwent emergency procedures. Treatment with Brilinta resulted in a reduction of death, heart attack, and stroke for at least one year, without an increase in major bleeding.

Brilinta’s introduction into the market could chip away at the Plavix domination in the category.

With patent expirations rapidly approaching, Big Pharma can’t risk losing even a small fraction of its blockbuster drug revenues to rivals. Plavix, developed jointly by Bristol-Myers Squibb (BMY) and Sanofi-Aventis (SNY), has been one of the best-selling drugs in the world since it hit the market 11 years ago, bringing in $4.5 billion in the first nine months of 2009. But the blockbuster blood thinner is set to lose patent protection in November 2011, leaving Bristol and Sanofi scrambling to replace the large chunk of their revenues.

Whether or not Brilinta will really hurt Plavix sales is yet to be seen, but Bristol said it wouldn't comment on the potential sales of a competitor. But the company had this to say in a statement:
 

Ticagrelor is an investigational drug and has not been approved by any regulatory authorities. Ticagrelor’s efficacy and safety have been studied in a clinical trial setting in the ACS population. We look forward to learning how health authorities evaluate the data supporting this investigational drug in order to have a better understanding of its potential utility.

Eli Lilly (LLY) also has a new drug that competes in the ACS space. Effient, which was approved in July and hit the market during the third quarter, had worldwide sales of $22.6 million during the time period. BMO Capital Markets analyst Robert Hazlett projects the drug will hit sales of $500 million by 2011 and have a sales peak of about $1 billion.

While Brilinta has a greater efficacy than the blockbuster blood thinner, a risk of bleeding could present a challenge when it tries to take on Plavix. “This direct-acting reversible inhibitor should provide an interesting option compared to both Plavix and Effient with some limitations,” said Hazlett in a note to investors. “An initial glance at the headlines regarding bleeding risk gives [Brilinta] a very positive impression, though a deeper look reveals similar risks to those seen with Effient, making it difficult for ticagrelor to escape the same cautions and warnings seen with Effient,” he added.

Miller Tabak analyst Les Funtleyder says Brilinta stands to be a bigger competitor of Effient, considering the amount of time left on the Plavix patent. He adds that both drugs should find their niche, but will likely not reach blockbuster status due to the competition from generic Plavix when that becomes available.