Yes but loperamide doesn't alleviate pain, which maybe just that opioids only alleviate pain if they do reach the brain, but I did see trials for non-bbb crossing ones that were for pain so not sure what's going on there.
It's possible that the analgesic and euphoric effects of opioids are one and the same. In other words, it's centrally dampening the experience of pain, both physical and mental. One is experienced as analgesia and the other as pleasure, but both may share the same mechanism, making one impossible without the other.
