What is the ruling on dealing with a brother who is still taking drugs despite being advised that it is forbidden?

Your brother is afflicted with a great trial, so deal with him gently and advise him. Exert every effort to prevent him from drug abuse and meeting bad companions. Do not accede to his demands if you can prevent them, and consult a specialized doctor. Make him see his condition while intoxicated through the testimony of his children, siblings, or other witnesses, and do not neglect to supplicate for his guidance in the last third of the night.