Which two medications are prokinetic agents used to increase motility?

Which two medications are prokinetic agents used to increase motility?

• A. Metoclopramide and Erythromycin
• B. Cisapride and Metoclopramide
• C. Loperamide and Metoclopramide
• D. Ondansetron and Erythromycin

Answer: (A)

Prokinetic drugs work by boosting the movement of the GI tract to improve gastric emptying and intestinal transit. Metoclopramide does this through a dual mechanism: it blocks dopamine D2 receptors in the gut (and in the brain) which removes an inhibitory influence on gut contractions, and it has 5-HT4 receptor activity that enhances acetylcholine release, leading to stronger and more coordinated contractions in the upper GI tract and increased lower esophageal sphincter tone. Erythromycin acts as a motilin receptor agonist, mimicking the natural hormones that trigger phase III motor waves in the migrating motor complex, thereby promoting gastric and small-bowel contractions. Together, these two provide practical prokinetic effects via distinct pathways—dopaminergic antagonism with serotonergic/gastrointestinal facilitation, and motilin receptor stimulation. Other options don’t fit as prokinetics: loperamide slows gut motility to treat diarrhea; ondansetron is a 5-HT3 antagonist used for antiemesis rather than promoting motility; cisapride is a prokinetic but is limited by safety concerns like QT prolongation, making it a less favorable choice in many settings.

Prokinetic drugs work by boosting the movement of the GI tract to improve gastric emptying and intestinal transit. Metoclopramide does this through a dual mechanism: it blocks dopamine D2 receptors in the gut (and in the brain) which removes an inhibitory influence on gut contractions, and it has 5-HT4 receptor activity that enhances acetylcholine release, leading to stronger and more coordinated contractions in the upper GI tract and increased lower esophageal sphincter tone. Erythromycin acts as a motilin receptor agonist, mimicking the natural hormones that trigger phase III motor waves in the migrating motor complex, thereby promoting gastric and small-bowel contractions. Together, these two provide practical prokinetic effects via distinct pathways—dopaminergic antagonism with serotonergic/gastrointestinal facilitation, and motilin receptor stimulation.

Other options don’t fit as prokinetics: loperamide slows gut motility to treat diarrhea; ondansetron is a 5-HT3 antagonist used for antiemesis rather than promoting motility; cisapride is a prokinetic but is limited by safety concerns like QT prolongation, making it a less favorable choice in many settings.