The first is new class. The brand examples are from my experience with Cozaar & Hyzaar, these are A-II receptor blockers for hypertension. The other is Celebrex. It was the first COX-2 inhibitor for arthritis.
The key claim in both of these was that they were first in a new class of treatments for their respective diseases. They were effective without causing a specific and well-understood side effect in the class.
In the case of Cozaar and Hyzaar, there was a reduced incidence of ACE inhibitor cough. In the case of Celebrex, there was greatly reduced NSAID gastrointestinal problem. Cozaar and Hyzaar went on to be long time, decades-long leaders in their class. Celebrex, as you might recall, and the COX-2 inhibitor class, hit a snag when there was some untoward cardiovascular side effects.
This idea of first in a new class of treatment is a commonly used promotional direction. In my experience, the regulatory lesson learned was that these claims of a different mechanism of action or new class of action must also be reflected in the clinical efficacy or safety of the product. It wasn’t enough to merely say it was a new class. It also had to demonstrate the clinical difference in either its effectiveness or its side effect profile.