Buzz has been building about who will either partner with or buy Amarin (AMRN 1.72%). The company plans to launch its lipid-lowering drug, Vascepa, in the first quarter of 2013 but still finds itself in the dating game

I don't claim to know which companies are actually among those in discussions with Amarin. There are no massive spreadsheets on my computer that I can use to predict with 99.5% confidence what will actually happen.

However, I do think that there are a couple of factors that will likely make the difference in who ultimately takes the plunge. One factor is motivation. Whoever the partner is needs to have a good reason to want Amarin. The other factor is money, especially if we're looking at an acquisition. 

With those two factors in mind, here are my top three candidates for partnering with Amarin. 

1. AstraZeneca (AZN 0.19%)
If you didn't think that AstraZeneca had plans to do some shopping, new CEO Pascal Soriot probably changed your mind. Soriot recently put the kibosh on the company's share buyback. Why take that kind of action unless he had something else in mind for the money?

London's Daily Mail reporter Geoff Foster speculated in October that AstraZeneca was possibly eyeing Amarin. Foster has been right on target in the past. Just last year, he correctly reported that GlaxoSmithKline (GSK 0.49%) was interested in buying Human Genome Sciences.

AstraZeneca sells several cardiovascular products, including Crestor, so the company already has a strong sales force in place that targets the physicians Amarin would probably want to go after. Vascepa would be a good fit into AstraZeneca's product lineup.

Should an acquisition be in the cards, AstraZeneca has plenty of cash to go shopping. With the share buyback on hold, the company has $6.8 billion in cash, equivalents, and short-term investments. Amarin's current market cap is $1.6 billion.

2. Merck (MRK 0.37%) 
A decent argument could be made that Amarin makes a good fit for Merck. Like AstraZeneca, Merck sells several cardiovascular products, including cholesterol drugs Vytorin, Zetia, and Zocor.

The problem for Merck is that sales are declining for two of these three drugs. Zocor sales for the first nine months of 2012 were 17% lower than the same period in 2011. Vytorin sales were off nearly 7%. Zetia experienced sales growth of almost 6%, but that wasn't enough to offset decreases from the other products.

Merck has also stopped development on two different cholesterol drugs in the past few months. The phase 3 study for experimental combination diabetes/cholesterol drug MK-0431E was halted this week for "business reasons." Another phase 3 trial for MK-0524B -- a combination of niacin, laropiprant, and simvastatin -- was put on hold in July.

The company would benefit from a strong addition to its lineup. Vascepa should fit well with Merck's statin drugs and Zetia. The company has a sales force that already calls on the physicians Amarin would target. Merck also sits on plenty of cash -- $17.4 billion at the end of September.

3. Eli Lilly (LLY 1.19%)
If there is any big pharma that needs a new product, it's Eli Lilly. Lilly continues to feel the brunt of Zyprexa going off patent. More patents expire in the next few years.

The same Daily Mail story that initiated the rumors of an AstraZeneca buyout of Amarin also referred to Lilly potentially having an interest. Lilly has cardiovascular drugs on the market but doesn't have an existing cholesterol drug. It is, however, conducting a phase 3 study with experimental cholesterol drug evacetrapib.

One intangible factor is that Amarin's CEO, Joe Zakrzewski, worked for Lilly from 1988 to 2004. Lilly's available cash currently stands at $6.9 billion, an ample amount to fund an acquisition of a company the size of Amarin.

Other possibilities
Any of these three companies could also be potential partners rather than acquirers. At least a couple of other companies should also be thrown into the mix. Abbott Labs (ABT 0.63%) and Pfizer (PFE 0.55%) would be the next two on the list. Both were also mentioned in the Daily Mail article. Both have plenty of cash to buy Amarin.

My guess is that the most likely scenario is an acquisition of Amarin by AstraZeneca. The second most likely scenario is "none of the above." In this case, Amarin would commercialize Vascepa on its own. A strategic partnership with one of the aforementioned companies would be the next most likely move in my view.

Of course, all of this is speculation for now. But the biotech world is full of speculation. We'll probably know something with 100% confidence within the next few months. No spreadsheets required.