I've ranted about this before on HN. The global pharmaceutical supply chain in a Cluster Fuck race to the bottom. Here are a few articles that Bloomberg wrote a few years ago:
http://www.bloomberg.com/news/articles/2014-03-06/flies-foun...
http://www.bloomberg.com/news/articles/2014-12-03/indian-lab...
IMO you're being deliberately naïve if you don't think that those sorts of manufacturing practices don't result in "defective drugs" reaching consumers.
Edit: here's a link to a Pfizer website. They make the claim that "VIAGRA is one of the most counterfeited drugs in the world." Do you expect us to believe that none of that counterfeit drug ever gets to consumers? https://www.viagra.com/getting/avoid-counterfeits