Praise be to Allah.
No doubt your brother is in a state of major crisis, and we ask Allaah to help you to deal with this crisis.
We advise you to be kind and gentle when you deal with him and advise him, because attention must be paid to his condition, just as with all other sick people – whether they are suffering from a disease of the mind or of the body.
You have to do everything you can to stop him from having the drugs and to stop him from meeting the bad friends who are giving or selling him the stuff and thus helping him to do wrong.
You should not give him anything he wants, if you can withhold it from him, until he gives up what he is doing.
We advise you to consult with a specialist doctor who can treat him properly until he gets better and gives up this habit.
If he has young sons or daughters, or brothers and sisters, we suggest that they should also advise him and denounce what he is doing. Perhaps then he will give up because he feels ashamed in front of his children or siblings.
You could describe to him, with the support of other people’s testimonials, how he looks and behaves when he is in an intoxicated state and is out of his mind, so that when he comes back to his senses he will see the evil sin that he has committed.
Do not forget to pray to Allaah to help him to get rid of this habit. Try to make du’aa’ during the last third of the night, and may Allaah show you the way out. We ask Allaah to guide him and to give you patience. May Allaah bless our Prophet Muhammad.