I'm no fan of the patent system, but "patent system promises spoils for coming up with great new drug, companies comes up with great new drug, companies gets spoils" is exactly how it's supposed to work. Yes, it's sucks that you have to pay, but that's how you incentives getting the wonder drugs invented in the first place. (I have my own take on this, but if anything this is a 'textbook case' in favour of the patent system.)
Eminent domain would still require fair compensation to the company, so you'd have to pay them more or less what they'd lose from not having the patent anymore.
(Though I think the term you might be looking for is 'compulsory licensing' or so? Not sure.)
Depending on how transformative the effects are (and the price drop possible upon genericisation) then there could be a compulsory licensing trade to do here.
The drug companies are presumably pricing optimally for profit (but not for maximum public benefit, for which the optimum price is ~0). You could calculate the net present value of the drug companies' total profits attributable to the patent, add on 10% as a bonus, and pay them off. If the welfare gains of having cheap drugs are genuinely greater than the value of the patent to the holder, this would be win/win.
Citation needed for the idea that zero is the optimal price for public benefit. Among other issues, I expect medication compliance would be higher when the patient has to pay for the medication.
I think we probably have data on that (at least in general). That is assuming people react to out-of-pocket payments, and not to how much their insurance or the NHS etc is paying.
That is exactly what I have in mind. "Eminent domain" doesn't mean just taking things with no recompense, but I don't think the company should be entitled to profit maximization at the expense of literally billions of people worldwide.
If this research was done fully via the public system in the first place, it would be an easier nut to crack. I mean, some of it is already, and that’s the absolute worst scenario: the public paid for it via taxes, and now has to pay for it privately after the fact.
Eminent domain would still require fair compensation to the company, so you'd have to pay them more or less what they'd lose from not having the patent anymore.
(Though I think the term you might be looking for is 'compulsory licensing' or so? Not sure.)