That then would create the ‘perverse’ incentive for poorer people who are dying of major diseases to sign up for any and all trials possible to lock in prices, regardless of relevance, and make things much, much worse for themselves due to misuse. Richer people would not do that since they can pay the full price without locking the old price in, so this risks converting the sick and poor people already battered by life into lab rats.

If you instead don’t enforce the requirement to actually take the drugs to lock in the price, then everyone signs up for everything and your drug companies will stop making any new drugs.