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Records continue to shatter across the markets as stocks keep up last week's big gains. The Dow Jones Industrial Average (DJINDICES:^DJI) certainly hasn't slowed down since last week, picking up another 73 points today as of 2:30 p.m. EST. The majority of the blue-chip stocks are in the green today, although leading Dow health care stocks have endured sluggish trading sessions. So far, Big Pharmas Pfizer (NYSE:PFE) and Merck (NYSE:MRK) only have managed to eke out slight gains of about 0.3% and 0.02%, respectively. Let's catch up on what you need to know.

Pfizer sets a date on Viagra's future
Pfizer investors and observers still are talking about the agreement announced last week with Teva Pharmaceuticals (NYSE:TEVA) to release Pfizer's famous erectile dysfunction pill Viagra as a generic medication in 2017. Teva will pay royalties to Pfizer under the deal, but don't discount the impact of a generic Viagra. The drug, despite its age, still remains a blockbuster therapy in Pfizer's drug portfolio; it made more than $1.4 billion through the first nine months of 2013 despite losing about 6% of its sales year over year.

Fortunately, 2017's a ways off for Pfizer, and the company will lose patent protection on the drug the same year that rival Big Pharma giant Eli Lilly will lose patent protection on its erectile dysfunction medication, Cialis. Still, it's a reminder that the patent cliff's danger hasn't ended for Pfizer following the withering hit to the company's revenue from the loss of patent protection on former top seller Lipitor. Lipitor's lost roughly half of its sales year over year through the first nine months of the year. While Viagra won't lose as much in sheer sales dollars as Lipitor, it's critically important that Pfizer's standout pipeline continues to deliver new replacements for older drugs.

Rival Merck's hanging near breakeven today after recalling much of its HPV vaccine Gardasil, bad news sparked by the report that some of one lot's vials could contain glass shards. The recall covers nearly 750,000 total vials of the vaccine, and although the Centers for Disease Control and Prevention said that potentially affected patients need not worry about complications, it's still an unwanted headache for Merck.

Nonetheless, Gardasil's been an unmitigated success for the company. With HPV a notable problem in America today, Gardasil -- one of only two vaccines approved by regulators to prevent the disease -- has become a hit. The drug racked up more than $1.4 billion through the first nine months of the year, equal to year-over-year revenue growth of more than 20%. While today's recall is a temporary hiccup in Gardasil's ascent, investors should still have confidence in this vaccine's strength as one of Merck's top-selling therapies for the long term.

Fool contributor Dan Carroll has no position in any stocks mentioned. The Motley Fool recommends Teva Pharmaceutical Industries. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.