Low Dose Naltrexone

What is the Straightdope on this?

Every now and then someone pushes it like its Arrakeen Spice, promising long life and health but then they go away

I am not sure I understand your question completely but Naltrexone is an opiate receptor blocker that is a prescription drug in the U.S. It certainly can extend life among opiate addicts and even alcoholics by making them not want have the impulse to do it so much anymore but it is used in conjunction with other treatments as well. There are related drugs like Acamprosate (Campral). It isn’t used for the general public at least in the U.S. and you can’t get it without good reason from a doctor. It is a good tool for addicts of various types including impulsive behavior but I am not aware of many other uses for it.