The issue here is that patent protection and the FDA acting as a gatekeeper, coupled with the requirement by schools that kids have the sole, regulatory-agency-approved-device, means that Mylan has more than just a monopoly. They have tremendous regulatory capture rents. In this case, Mylan's competitor was removed from the market by the FDA for having a failure rate that is, supposedly, the same as Mylan's. Once that happened, Mylan was free to jack up prices, and they did.
One article I read suggested that an easy fix is to make Epi-pens over the counter, rather than prescription, which would make it easier for competitors to get approval. Here: http://www.cnbc.com/2016/08/23/epipen-prices-are-out-of-control-heres-how-we-fix-the-problem-commentary.html
Thanks for this insight. Yup, regulatory capture, rent seeking, etc. I believe the solution for this problem, that seems to have been caused through over-regulation, is most likely more regulation.