Fantasy flight games has provided several consumable drugs for RT but neglected to provided rules for them beyond their initial effects. Drugs are probably one of the most interesting facets of the world and a great character flaw for a PC.
Just as in real life there should be consequences and benifits for a character who uses these substances. While morphine can provide relife from pain and make life saving surgerys possible it's darker side is the potential addiction it can bring to the one who uses it.
Psychadelics can provide clarity to those studying the mind as to how it works and to users it can provide profound life altering experiances, unlocking thoughts and ideas you would never have come to without them. Once again the dark side is the bad trip or at worst permenant madness.