My brother in law passed away recently. did not wake up. He abused drugs. He had Xanax , vicoddin, methadone , trazodone, clonazepam in his system. Been on drugs for a long long time. Did this stop his heart, or is it considered a heart attack from all the drugs. Nothing Medical was wrong except addiction to pain pills after a accident many years ago. I was told that Methadone and xanax should never be taken together. is that true? thank you pj