I found it interesting that Loperamide HCL hits just the opioid receptor that stops colon activity — that’s how it stops diarrhea.
I just found out yesterday that Loperamide is a form of demerol that doesn’t cross the blood/brain barrier, but does effect the opioid receptors in the gut. That’s how it stops constipation.
From what I read, addicts are using it to ease the symptoms of withdrawal in an effort to get off drugs.
Loperamide has the same affinity for mu opioid receptors as opiates. It is just a happy accident that loperamide is almost immediately pumped out of the brain by a glycoprotein thus limiting the effects to those receptors outside the brain.