New rules set forth by Google in the past days will tighten up regulations for advertising drugs online. The new regulations set in place by Google will limit advertisers to placing ads online only in their respective countries.

This means that Canadian pharmacies will only be allowed to show their ads in Canada, American pharmacies in the United States, and so on and so forth.

According to an article from Barron’s, this could have a pretty big impact.

That sounds both logical and esoteric, but it has ramifications for ad revenue. Benjamin Schachter, an analyst with Broadpoint.Amtech, notes today that a test search of each of the top 10 best-selling subscription drugs on Google found that 68% of the ads on the first page of search results were from Canadian online pharmacies that would be disallowed under the new rules. For the top five drugs, 76% of the ads were for Canadian online pharmacies. (Try it; search for Lipitor, Nexium, or Plavix.)

Google says that the change will cause a slight drag in revenue, but I am sure that big pharma is more than making up for the difference somehow.

Yesterday a report was released that found combining the heartburn medication Prilosec with the blood thinner Plavix can decrease the effectiveness of the blood thinner by 50 percent, putting the user at greater risk for strokes and heart attacks.

“These recommendations are based upon recently submitted studies by the manufacturer of clopidogrel [Sanofi-Aventis and Bristol-Myers Squibb],” Mary Ross Southworth, deputy director for safety with the U.S. Food and Drug Administration’s Division of Cardiovascular and Renal Products, said during a morning press conference.

“The results of those studies are to avoid the combination of those two medications,” she added. Even if the two drugs are taken separately hours apart the negative effects can still be experienced.

The worst part about it is that this is a very common combination because Plavix has been known to cause upset stomach. The good news is that some alternatives to Prilosec are safe, such as Mylanta, Maalox, and Zantac.

According to US and World News Report, proton-pump inhibitors similar to Prilosec — such as Aciphex, Nexium, Prevacid and Protonix — should also be avoided when taking Plavix.

Watch out for these other drugs that may also react with Plavix, making it less effective: cimetidine (Tagamet), fluconazole (Diflucan), ketoconazole (Nizoral), voriconazole (Vfend), etravirine, felbamate (Felbatol), fluoxetine (Prozac), fluvoxamine (Luvox), and ticlopidine (), according to the FDA.