Really interesting thread, thanks to everyone who contributed. The activity of salvia is due primarily to it being a potent kappa agonist so its quite an interesting receptor. There is an analogue of salvinorin A called herkinorin which happens to have far greater affinity for mu receptors than salvinorin A. I would be very interested in its potential application as an anti addictive opioid for free people from addiction to mu agonists like heroin.