Or maybe that's just an excuse pharma companies use because they'd like to have their cake and eat it, too. If they didn't actually want to sell their drugs for pennies on the dollar in some countries, they wouldn't.
If they are "forced" to sell there, it's only because of two reasons:
1) the US companies started selling there of their own free will, and after their patents expired in those countries, other companies were free to use the formula
2) Other companies would have created the same drugs with or without their patents, and the American companies would've lost all of that market share/brand image in that country. And I bet the competitors would do it for a tiny fraction of the faux R&D costs Big Pharma likes to claim for inventing a new drug.
Besides, the idea that if a company patents something that means it's the only one that could have ever invented that thing needs to die already. The "first to file" patent system that has been adopted in most major countries because of big companies' lobbying is another dead-giveaway that this whole idea is bogus. Why would you have a "first to file" if you didn't have multiple people inventing the same thing at the same time.
Many people or groups of people can come up with the same invention around the world roughly at the same time. Often, those alternatives don't become popular because their papers are in their native tongue and they lack investment, but the "invention" was already made.