I agree with your bit about prescriptions. However I don't think following "the SpaceX model" would be very useful (or even a good idea) here. A few reasons:

I agree with your bit about prescriptions. However I don't think following "the SpaceX model" would be very useful (or even a good idea) here. A few reasons: 1) the housing and needle are dirt cheap to manufacture, and as you said, it's the patent that is expensive and replaceable cartridges wouldn't get around that 2) much of the safety of these things is the clear labeling around expiration and such 3) the risk of improperly replacing a cartridge far outweighs the benefit of reusing a bit of plastic 4) you could only replace un-used epi-pens, as replacing the needle sounds dangerous