Is it permissible to consume drugs and alcohol out of necessity to alleviate pain and due to an inability to stop them?

It appears the question is incomplete. All intoxicants are forbidden and must be avoided and abandoned. An addict seeks a permissible remedy for the pain he feels. Allah has not sent down a disease without also sending down a cure for it. He has prescribed permissible treatments and forbidden unlawful ones, as stated in the Hadith: "Indeed, Allah has sent down both disease and remedy, and for every disease, He has made a remedy. So, seek treatment, but do not seek treatment with unlawful things." And in a Hadith narrated by Bukhari: "Indeed, Allah has not made the cure for my Ummah in what He has forbidden to them." The Messenger of Allah (peace be upon him) also forbade seeking treatment with alcohol.