We said goodbye to Wyeth three weeks ago,
Pfizer (NYSE:PFE) took it from our sight.
Today it's Schering-Plough's heave-ho,
Merck (NYSE:MRK) closed the deal last night.

Technically, Schering lives on as a quirk;
It was a reverse merger, after all.
But after Schering bought Merck
As "Merck," it answers the call.

Change in control or reverse merger deal?
Only an arbiter will decide.
Non-U.S. Remicade sales are on appeal;
Johnson & Johnson (NYSE:JNJ) no longer wants to divide.

Like Bristol-Myers Squibb (NYSE:BMY)-Medarex and Eli Lilly (NYSE:LLY)-ICOS,
Partners can be acquired.
Using Vytorin-plus-Zetia to get close
Actually may have backfired.

But Schering's pipeline also has gusto.
Merck's is a bit of a mess.
Many weren't developed by Schering, though,
But through Organon BioSciences' largesse.

Only $14 billion that deal was costing;
It came with lots of drugs to boot
Which made Merck's acquisition exhausting,
Organon brought animal-health product loot.

You see, Merial was Merck's joint-venture bride,
With sanofi-aventis (NYSE:SNY) it paired.
But Merck having something of its own on the side?
"Absolutement non!" Sanofi declared.

Merck, its half of Merial did sell
To Sanofi, the partner, it went.
But the previous partners could once again gel;
Sanofi has the option to relent.

The question now's how well the merger will go,
Merck doesn't have much experience with that.
Uniting with Schering mightn't help much, though.
ROEs, after big mergers, often go splat.

To Schering we bid our fondest adieu;
Founder Ernst might weep at the shame.
Your German sibling has shuffled off, too,
But Bayer, at least, saved his name.

Is the new Merck stronger or weaker than the old one? Let us know what you think in the Motley Fool CAPS. Make an out- or underperform call on Merck, Pfizer, or the other mega-pharma companies.  It's free, fun, and Foolish.

Pfizer is a Motley Fool Inside Value recommendation. Johnson & Johnson is a Motley Fool Income Investor pick. Try any of our Foolish newsletter services free for 30 days.

Fool contributor Brian Orelli, Ph.D., doesn't own shares of any company mentioned in this article. The Fool has a disclosure policy.