PAMORAs act by inhibiting the binding of<unk> s agonist to the<unk><unk><unk>  (MOR). The objective of PAMORAs treatment is to restore the enteric nervous system function (ENS). The MOR is found in several places in the body and PAMORAs is a competitive<unk>  for binding to the<unk> . The MORs in the gastrointestinal tract are the main<unk> s that PAMORAs are intended to block and prevent the binding of<unk>  agonists. PAMORAs are used in the treatment of<unk> -induced bowel dysfunction (OIBD), a potential adverse effect caused by chronic<unk>  use. PAMORAs act on the three pathophysiological mechanisms of this adverse effect. They act on gut motility, gut secretion and sphincter function. PAMORAs effect on gut motility is that it can increase the resting tone in the circular muscle layer. The<unk>  enhances the effect on tonic inhibition of the muscle tone. This will normalize the tone in the circular muscle layer and therefore prevent<unk> -induced rhythmic contractions. When these two factors are combined, it results in decreased transit time. Impliedly these effects will decrease the passive absorption of fluids which helps with decreasing OIBD symptoms such as constipation, gut spasm and abdominal cramp. PAMORAs effect on gut secretion will help reverse the decreased cAMP formation that<unk>  agonists induce. Also, the<unk>  will establish a normal secretion of chloride.<unk> s agonists can also reduce the secretion of peptides by increasing the sympathetic nervous system through the<unk><unk> s in the ENS, which can lead to drier and harder stool. PAMORAs work against it so the stool becomes softer and less dry. PAMORAs effect on the function of the sphincter is in theory to regulate the movement coordination. The<unk>  can prevent sphincter of Oddi dysfunction that is caused by<unk> s.<unk> s can also reduce<unk> -induced anal sphincter dysfunction. The dysfunction is tied to straining, hemorrhoids and incomplete emptying.
Peripherally acting μ-opioid receptor antagonist
Serotonin–dopamine releasing agent
Serotonin receptor agonist
Norepinephrine–dopamine releasing agent
Serotonin–norepinephrine–dopamine releasing agent
Long-acting beta-adrenoceptor agonist
Noradrenergic and specific serotonergic antidepressant
Serotonin–norepinephrine releasing agent