Newsgroups: alt.drugs
From: [g--g--y] at [rintintin.Colorado.EDU] (Scott Grigsby)
Subject: Why opium causes constipation
Date: Fri, 11 Feb 1994 02:23:24 GMT

Well, I bugged all of you to tell me why opium causes constipation.
I hadn't received a reply, so while on my way to class today
I stopped at the library (and never quite made it to class.  The
library has that effect...).  When I got home, I found that someone
had sent me a reply, confirming what the library told me.  So here's
what I found out (you're dying to know, aren't you?):

The gastrointestinal tract contains many opioid receptors (gamma,
kappa, and sigma, I think), to which the opiods bond (duh).  
The rest I'll copy from this book (I forgot the title, but the 
authors (of this chapter) are T.H. Bewley and A.H. Ghodse):

"There is a decrease of motility with increase in tone of the central
part of the stomach.  There is an increase tone in the first part
of the duodenum...  Digestion of food in the small intestine is
delayed where propulsive contractions are markedly decreased.  The
action on the small intestine is thought to cause about a quarter
of the total constipating effect.  In the large intestine, 
propulsive peristaltic waves in the colon are diminished or
abolished after morphine.  Delay in passage of contents causes
dessication of feces.  Anal sphincter tone is augmented."

So that's it.

Scott
-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\__________/~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
               Scott Grigsby   ///-///-///  The cut worm forgives the plow. 
                               \\\-\\\-\\\                       -Blake 
    [g--g--y] at [rtt.colorado.edu]   ///-///-///