The US Food and Drug Administration has hit both Pfizer and Bayer with warning letters, saying that advertisements for the respective drugs – the allergy medicine, Zyrtec (cetirizine), and the erectile dysfunction offering, Levitra (vardenafil) – are misleading.

The letter to German company, Bayer, which was copied to its partners, Schering-Plough and GlaxoSmithKline, said that a direct-to-consumer television advertisement failed, among other things, to include information relating to the major side effects and contraindications. In addition, the agency says that Bayer implied that its product was superior to competing offerings.

With regard to Pfizer, the agency specifically took issue with three DTC ads that claim that Zyrtec “works” when some other allergy medicines do not. For each of the ads, the text under the headline states: “Your allergy medicine should work on all of your indoor and outdoor allergies. Really work. Why put up with a medicine that only treats outdoor allergies? Shouldn’t it cover both?”

In its letter, the agency says that there is an “overwhelming message from the text and the visuals of these ads is the comparative claim that Zyrtec is more effective in treating allergies in general, or certain types of allergies, than some other allergy products, which are not effective.” However, it adds that it is not aware of substantial evidence or substantial clinical experience demonstrating that Zyrtec is clinically superior to any other available OTC and prescription oral allergy medicine. In addition, the FDA says it is not aware of substantial evidence or substantial clinical experience showing that patients who fail on other allergy drugs will be effectively treated by Zyrtec, as the ads suggest.

Both companies have been ordered to immediately pull the ads in question and submit written responses by 27 April stating their plans to comply with the requests and how they plans to “disseminate truthful, non-misleading, and complete corrective messages about the issues discussed.”

- Meanwhile, Belgian company, UCB, which licenses Zyrtec to Pfizer in the USA, says that GSK Japan will be the new co-distributor for the 5mg and 10mg tablet versions of the product in Japan as of July this year.