This morning the Dow Jones Industrial Average's (DJINDICES:^DJI) two big drug companies and a number of smaller drug-related companies announced earnings. The Dow itself is flat just before noon, and its drug-manufacturing components are mixed: Pfizer (NYSE:PFE) is up 0.4%, while Merck (NYSE:MRK) is down 0.6%.

Pfizer was expected to post revenue of $13.01 billion and earnings of $0.55 per share, and it only managed to beat on the bottom line while missing on the top, posting sales of $12.97 billion and EPS of $0.59. Despite the slight sales miss, shares are higher after management said it will hit its full-year EPS guidance of $2.10 to $2.20. Further, the company's CEO announced that the company will be reorganized into three business units. One will produce Pfizer's generic drugs, while the other two will focus on the branded products. Some believe this move may be setting the foundation for Pfizer to spin off its generic-drug business sometime in the future.  

As for Merck, Wall Street wanted to see revenue of $11.22 billion and EPS of $0.83. But like Pfizer, Merck missed on the top line and beat on the bottom with sales of $11.01 billion and EPS of $0.84. The disappointing revenue figure owed partly to an 80% decline in sales for asthma drug Singulair.  

Herbalife (NYSE:HLF), the health and nutrition company that has drawn attention from activist investors and a big short position by Bill Ackman, also reported earnings last night, and its $1.41 in EPS crushed analysts' expectations of $1.18. Revenue also beat expectations after quarterly sales growth came in higher than many had predicted. The company also increased its full-year EPS forecast. This morning DA Davidson increased its price target to $92 and reiterated its buy rating on the stock after seeing last night's results. 

Lastly, shares of Express Scripts (NASDAQ:ESRX) are down 2.8% even though the company beat on both the top and bottom lines and increased its full-year earnings forecast. The one downside to the earnings report is that Express Scripts' CFO is leaving and the company's dynamics are changing underneath its feet.

All of the companies above have begun to benefit from the retirement of the Baby Boomers. Whether it's Herbalife's nutritional supplements, Pfizer's cholesterol-lowering medication, or Express Scripts' delivery service, all four of the businesses above will likely continue to benefit from a healthier, longer-living American. But that's not to say that each company doesn't have its own set of problems, such patent expirations, CVS Caremark's move into the drug delivery business, or activist investors fighting over a company and its financials.

Investors need to continue following the story lines of each company to see what may be around the corner before it's too late.

Fool contributor Matt Thalman has no position in any stocks mentioned. The Motley Fool recommends Express Scripts. The Motley Fool owns shares of Express Scripts and has the following options: long January 2014 $50 calls on Herbalife Ltd.. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.