AstraZeneca (NYSE:AZN) is one of the globe's biggest drug companies. The company generates more than $20 billion in annual sales, and given its dividend yield is nearly 4%, its shares are often included in dividend investor's portfolios.

Although AstraZeneca has recently jumped because of M&A interest from Pfizer (NYSE:PFE), investors are right to wonder whether patent expiration on top selling drugs and falling margin could threaten AstraZeneca's dividend if it remains an independent company.

In the following slideshow you'll learn whether I think AstraZeneca's dividend is safe and see how AstraZeneca's dividend matches up to Pfizer and former diabetes partner Bristol-Myers (NYSE:BMY).