That's Baloney. I don't know about Mexico but drugs are not advertised in Canada and the pharmaceutical companies spend far more on advertising in the US than they do on R&D, which incidentally, is largely covered by tax incentives, out right grants and University research programs. And not all drugs are discovered and developed in the US
The US consumes 42% of the world's prescribed drugs, twice the Canadian consumption per person, and pays twice as much. The second highest net profit for industrial sectors was around 5-6%. For the pharmaceutical sector last year in the US profit was the highest , 18%.
My understanding is that a large fraction of what is lumped under advertising is free samples given to Doctors who in turn give them to patients - in other words free drugs. Yes, that is "advertising", but it is not what most people think of when they hear the word advertising.