The National Hockey League is not playing, but Wall Street has the seat in a penalty box warmed and ready for action for a couple of premier players -- the drug giants in the Dow 30.

Entering the penalty box in October was Motley Fool Income Investor recommendation Merck (NYSE:MRK) and Vioxx, its COX-2 inhibitor (a non-steroidal anti-inflammatory) pain medication. It was recalled because studies showed "cardiovascular events, such as heart attack and stroke, beginning after 18 months of treatment in the patients taking Vioxx compared to those taking the placebo."

The loss of projected annual sales of over $2.5 billion was like getting slammed in the head with a hockey stick. Merck's already-weak share price plummeted from the mid-$40s to the mid-$20s.

Skating off the ice and into the penalty box today is Pfizer (NYSE:PFE), with an announcement that two long-term cancer studies are giving conflicting results on the cardiovascular safety of COX-2 inhibitor Celebrex.

The result of the adenoma prevention with Celecoxib (APC) trial led to Pfizer's stock falling as much as 24% this morning. Patients taking 400mg and 800mg of Celebrex daily had an "approximately 2.5 fold increase in their risk of experiencing a major fatal or non-fatal cardiovascular event compared to those patients taking placebo." The National Cancer Institute has suspended the dosing of Celebrex in the study.

The typical Celebrex patient with arthritis or pain takes 100mg to 200mg daily. Those with rheumatoid arthritis take 200mg to 400mg a day. Pfizer made a point of mentioning, in reference to previous studies and user experience, that "increased risk of serious cardiovascular events in arthritis patients, even at higher-than-recommended doses, had not been seen." So, Celebrex sales continue.

It's ironic now but, at the time of the Vioxx recall, many thought Pfizer's COX-2 inhibitors -- Celebrex and Bextra -- would benefit. Pfizer's stock, though, has drifted down since the Vioxx news.

Value investors may see Pfizer's stock as an open hockey net ready for them to slam home their investment buck for a winning score. Income investors may look at the 2.7% yield and see a favorable risk-reward trade-off. Others will see Celebrex, the most widely prescribed drug for arthritis, with annual sales approaching $3 billion (roughly 6% of Pfizer's total sales), as a problem child that is going to get to know a lot of lawyers.

Pfizer is already sporting a hockey player's chipped-tooth smile from today's news. The upcoming regulatory spotlight on all COX-2 inhibitors could also lead to more face-smashing. Wise investors would step aside, avoiding these painful pain drug problems and letting the fight rage without them.

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Fool contributor W.D. Crotty does not own stock in any of the companies mentioned but has been prescribed Celebrex in the past.

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