It looks like the rumors about one drugmaker deal have come to fruition. MGI Pharma (NASDAQ:MOGN) announced yesterday it was being acquired by Japanese pharma giant Eisai for $3.9 billion.

Less than two weeks after MGI announced that it was seeking strategic alternatives, Eisai agreed to pay $41 per share in cash to acquire the company. The deal with Eisai makes sense ... for MGI investors, at least. MGI's top drug is chemotherapy-induced nausea treatment Aloxi, which constituted the majority of MGI's $289 million in revenue for the first nine months of 2007. Aloxi's sales growth has been anemic this year, though, thanks to generic competition hitting its rival drug, GlaxoSmithKline's (NYSE:GSK) Zofran.

Aloxi sales are only now starting to recover from the indirect generic competition. MGI's biggest future growth prospects are myelodysplastic syndromes treatment Dacogen, which has already been approved, and sedative Aquavan, for which MGI had filed a New Drug Application in September.

It's hard to see many synergies for Eisai from the acquisition. Eisai's top drug is an Alzheimer's disease treatment, and its marketed products and pipeline regarding oncology are directed more toward solid tumors. Considering that MGI's compounds are all small-molecule drugs, Eisai also won't get to benefit from the de facto generic-free competition that biologics receive even after their patents expire.

It can be disappointing when shares of a drugmaker you've owned for years are taken away just as its assets are ripening. But Eisai is paying a healthy premium compared to before MGI announced it was up for sale, and investors no longer have to worry about all the regulatory, pipeline, and competitive risks that could dog Dacogen and Aquavan.

Last month, Dacogen's biggest competitor, Pharmion's (NASDAQ:PHRM) Vidaza, was acquired by deep-pocketed rival Celgene (NASDAQ:CELG). The Pharmion deal ratcheted up the competitive worries over Dacogen, and Aquavan is far from a sure bet to get FDA approval next year. Therefore, in the case of MGI, "take the money and run" seems like a safe strategy.

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Fool contributor Brian Lawler does not own shares of any company mentioned in this article. Glaxo is a selection of the Income Investor newsletter. The Fool has an A+ disclosure policy.