This is unsupported by any serious literature. Economic theory tells us that the only circumstance in which this happens is an industry prone to natural monopoly, which are generally those constrained by geography and enormous fixed infrastructure costs coupled with relatively constant marginal costs.
The "natural" long-run state of free markets is economic equilibrium, which necessarily includes competition to reduce marginal profits to around zero at the point that the amount supplied is equal to the amount demanded.
The only reason DataPrim price could be hiked was that the people who need it will actually pay for it. Same with ACTH. A captive audience is a wonderful thing -- something Coca Cola would love but doesn't have.
There were ~100 car manufacturers 100 years ago, how many are there now? (And cars are not as essential as ACTH)
There were tens to hundreds of media companies up until the 1980's. Now, there are essentially six[0]. And if antitrust didn't matter, there would probably be less.
Similar things are happening in pharma[0].
It is one aspect of capitalism that's to blame: "free market". If you monopolies are legal (and in a totally free market, they are), then you will get monopolies because they are more effective at extracting rent than competition. we've just seen this happen twice in the pharma market.
[0] https://en.wikipedia.org/wiki/Media_cross-ownership_in_the_U...
[1] http://www.ft.com/cms/s/0/6aad8ebe-e9c0-11e4-b863-00144feab7...
The US market (like most real markets) is neither "naturally regulated" nor a libertarian "free market".
A "naturally" regulated market eventually converges into one all-powerful monopoly player - it's a stable configuration that maximizes the profit for the owners of that monopoly.
So you have to regulate this "freedom" away from disappearing - in the same way that GPL regulates BSD freedom away from disappearing.