"It is often assumed that generic drugs are affordable and widely available to those who need them. But this is not entirely true. For example, even after patent expiries open the door to generic rivals, low levels of competition between companies in smaller markets means that generics can actually be more expensive in poor countries than in wealthy ones."

https://www.ft.com/content/99d64932-fd04-488f-9c63-b3646083cbbc