My solution would be very unethical.
Mine wouldn’t. Seal up the junkies in a huge, hardened sealed empty building and install drug vending machines. Free. They can request to leave, once. Immediately into a serious drug rehab program. Any slip, back into the building forever until they die.
There are cameras everywhere 24/7 filming. People pay to subscribe monthly to watch. Helps subsidize the costs.
Only thing the living junkies have to do is drag the dead ones each week into a hardened designated room biohazard staff can secure to collect them. If they dont the vending machines get weaker diluted drugs.