ABSTRACT
Opioids inhibit gastrointestinal (GI) motility, especially by binding at and activating (acting as agonists at) mu () opioid receptors in the intestinal tract. The major mechanism for the effect of these drugs on bowel function is believed to be activation of these receptors in the colon. The resulting inhibition of peristalsis can produce opioidinduced constipation. This chapter briefly reviews the physiology and pharmacology associated with the binding of opioids to opioid receptors in the GI tract. It provides a brief overview of normal GI motility and what occurs when opioids bind to the receptors, interrupting bowel homeostasis.
