Just some of my thoughts...
Why does one drink or do drugs? That is probably the most important question about the subject.
Does a person take morphine that is prescribed to relieve pain? Or does that person take it to alter their mind? Does a person smoke marijuana for medicinal purposes or for the "high"? Does a person drink a glass of wine with dinner for the taste or to get a "buzz"? When one can answer those question....HONESTLY....then I believe they have the real answer whether it is wrong or right.
I used to be an alcoholic and a drug addict myself. I probably drink the equivelant of one glass of wine every 4-6 months now. And drug use is gone, unless you count any prescriptions I have recieved from a doctor, ie. Lortab, Vicodin, etc...for pain management. Do I abuse them? No. I use them to manage pain, when the pain is gone, I quit taking them.
If you take a mind-altering drug, with the purpose of altering your mind, then it is wrong. God knows your purpose.
If you have Jesus in your life, then becoming addicted to drugs and alcohol should be easy to combat.(remembering the bad hangovers helps too...lol)
I'm not sure how biblically based my answer is, I don't have my bible at work today, but it seems to me if your are altering your mind, with the purpose of altering your mind, then you are losing focus on Jesus.