Wow, what a difference a year makes.

Last year, I wrote about how laughable it was that Merck (NYSE:MRK) put out conservative guidance of just a 7% increase in adjusted earnings per share at the midpoint of the range.

Now, nobody is laughing. It looks like Merck will just barely make the range it set out last year, and the company has guided for potentially lower adjusted earnings next year.

It's not just one problem for Merck, but a series of issues that have turned the company into a heap of stale drugs. Cholesterol-lowering drugs Vytorin and Zetia, marketed with Schering-Plough (NYSE:SGP), are still languishing from the Enhance data and probably won't see a major turnaround until the duo gets some data proving that the drugs decrease cardiac events, not just cholesterol levels.

Growth in sales of Merck's human papillomavirus (HPV) vaccine, Gardasil, has stalled as well. Sales are expected to be flat next year, assuming the company can get the vaccine approved for older women and to protect males from warts. That also assumes that GlaxoSmithKline's (NYSE:GSK) Cervarix doesn't take more of a bite out of Merck's monopoly in the U.S. should Cervarix get approved next year.

The bigger problem for Merck is that it doesn't have anything to get the revenue growth back on track. The FDA turned down cholesterol drug MK-0524A, and now it won't be on the market until 2013 at the earliest. And development of its potential-blockbuster diet drug, taranabant, got canned after a phase 3 trial showed that, like Sanofi-Aventis' (NYSE:SNY) Acomplia/Zimulti, the drug also caused psychiatric problems.

Maybe the company should use some of its $6.8 billion in cash and investments to buy some new drugs, much like Eli Lilly (NYSE:LLY) has done or Pfizer (NYSE:PFE) might be considering. Without that, I'm having trouble seeing how Merck will increase in the next few years. However, current investors aren't in a horrible position, either. With the substantial share-price drop so far this year, investors are now getting paid a whopping 6.1% dividend yield to wait on top of the trash heap.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.