That is the the problem, they are NOT free to do so.
One company owns the patent. They are the only ones who can make it.
Why a 40 year old drug is under patent is a good question.
I don't claim to be an expert on this issue.
The patent on the drug I take ran out 18 months ago. The generic maker was already making the drug in India despite American patents.
The Indian company wanted to incorporate improvements in the formulation that had been made after the original patent and which were protected by a newer patent. They made a non-compete deal lasting six months in exchange for being licensed to use the improvements.
For reasons I don't know, the generic is not approved by the FDA for my ailment. As long as my drug insurance company covers the brand name, I don't care. I prefer to stick with what I already know and not risk some unexpected side-effects from the generic. (Surprisingly, this generic costs about 85% of the cost of the brand name.)
I think the same people who harp about high drug prices also want to levy substantial penalties and damage payments on these same companies when things don't work perfectly. An example of this is Xarelto. I think this was responsible for my bout of unexplained bleeding years ago and additional medical risk and procedures. Despite that, the drug is still on the market and helps many. It's just not for me.
In my opinion too many people just don't appreciate how great we have it and want to change what works well into what won't work much at all. I can't prove it conclusively, but I would bet that I wouldn't be alive today if one removed any one of a dozen medical developments of the last fifty years. This includes intubation equipment and procedures, cat scans, modern antibiotics, blood testing, anesthetics, cancer drugs, and genetic testing.
We're all gonna die. Some will die because there isn't time to get them medical help. Some will die because the help doesn't work. And some will die because the help they need is too expensive. This will never change. If expense were no object, there would be a fully staffed ambulance with its engine running parked outside my front door.
‘Why a 40 year old drug is under patent is a good question.’
seems like there’s something more to this whole story...a drug on the market cannot under normal circumstances be price protected by patent...