Bristol-Myers Squibb

The pharmaceutical industry is ready to fall off a cliff -- a "patent cliff." Over the next few years, some of the world's most popular and lucrative medicines will go off patent, and generic competition will siphon an estimated quarter of a trillion dollars from drugmakers' bottom lines.

Pfizer reported fourth-quarter earnings on Tuesday that nearly quadrupled from a year ago as revenue rose 6%. But it also lowered its sales guidance for 2012, due to some of its bestselling drugs going off patent. What's ahead for the world's biggest drugmaker:

Sanofi-Aventis announced its cancer drug candidate iniparib failed in a late-stage clinical trial. Other pharmaceutical companies have also experienced recent setbacks as they scramble to bolster their pipelines ahead of the patent cliff, when they will be forced to compete with cheaper generics.

Diabetes is a growing global scourge, but for Big Pharma it's more of a lifesaver -- and many drugmakers are cranking up their research efforts. After all, many existing drugs will soon be losing their patents, and diabetes could be a $55 billion market by 2019.

The FDA disappointed AstraZeneca and its investors by not approving its heart drug Brilinta, a blood-thinner that the company -- facing a severe patent cliff -- has high hopes for. If approved, it could be a multibillion-dollar blockbuster. But the FDA wants to see more analyses of results from a major study.

More than a year after AstraZeneca filed for approval, the FDA will make its decision on Thursday. A large study showed the blood thinner worked better than Plavix for treating acute coronary syndrome -- but approval isn't a sure thing, due in part to some oddities in the study's results.

At a liver disease conference in Boston, one highlight is expected to be reports from Achillion about its new hepatitis C treatments, especially ACH-1625. The buzz is growing that the little biotech is attracting the attention of some players in Big Pharma.