GI Motility - Pro Kinetic Agents

Question 1

What is the immediate mediator of smooth muscle contractility?

Answer 1

Acetylcholine

Question 2

Which drug can act as an agonist at the 5HT-4 receptors to enhance gastric motility?

Answer 2

Cisapride

Question 3

Which muscarinic agonist can stimulate M2 and M3?

Answer 3

Bethanechol

Question 4

How would you block motility?

Answer 4

Anti-cholinergic agent since they cause constipation

Question 5

Are D2 agonists Pro or Anti motility?

Answer 5

Anti-motility because they inhibit the release of acetylcholine

Question 6

Which D2 antagonist (prevents the actions of dopamine) is given to enhance motility (by inhibiting acetylcholine release)?

Answer 6

Metoclopramide

Question 7

Which is a benzamide that enhances the motility of smooth muscle from the esophagus to the proximal small intestine and accelerates gastric emptying from the duodenum to the ileocecal valve?

Answer 7

Metoclopramide (Reglan)

Question 8

What is the net effect of metoclopramide?

Answer 8

Accelerate gastric emptying and reduce reflux from the duodenum and the stomach into the esophagus

Question 9

Which agent sensitizes muscarinic receptors on intestinal smooth muscle to the actions of acetylcholine?

Answer 9

Metoclopramide

Question 10

Does metoclopramide cross the blood brain barrier?

Answer 10

Yes. It produces most of the CNS side effects characteristic of D2 receptor blockade such as anti-emesis, hyperprolactemia, breast tenderness, menstrual irregularities, and extrapyramidal syndrome at high doses

Question 11

What is metoclopramide used for?

Answer 11

• Treatment of diabetic gastroparesis
• esophageal reflux
• nausea and vomiting including pregnancy and chemotherapy

Question 12

Which D2 antagonist does not penetrate well into the CNS so its effects are confined to the periphery?

Answer 12

Domperidone (Motilium)

Question 13

Which is a better anti-emetic, 5HT-3 antagonist such as Zofran or metoclopramide?

Answer 13

5HT-3 antagonist

Question 14

Which agents inexplicably are not reduced by muscarinic cholinergic antagonists?

Answer 14

Domperidone (have the same effects on gastrointestinal motility than metoclopramide)

Question 15

Which D2 antagonist produces hyperprolactemia at the anterior pituitary?

Answer 15

Domperidone, Metoclopramide

Question 16

What is domperidone used for?

Answer 16

Same as metoclopramide including anti-emetic even though it does not cross the blood brain barrier

Question 17

Which agent is used for compassionate use only?

Answer 17

Cisapride (Propulsid)

Question 18

Which benzamide increases colonic motility and can cause diarrhea?

Answer 18

Cisapride

Question 19

What blocks the gastrointestinal actions of metoclopramide and cisapride

Answer 19

Atropine

Question 20

Does cisapride influence the concentration of prolactin or cause extrapyramidal symptoms?

Answer 20

No because it does not block the D2 receptor

Question 21

Cisapride is metabolized by what enzyme?

Answer 21

CYP3A4

Question 22

What is Cisapride used for?

Answer 22

Same as metoclopramide and domperidone with the advantage of none of the side effects associated with dopaminergic blockade. Used mainly for esophageal reflux

Question 23

What drug interactions are seen with cisapride?

Answer 23

It prolongs the Q-T interval so it can cause ventricular fibrillation at high doses. Drugs metabolized by CYP3A4 are contraindicated (erythromycin, ketoconazole, nefazodone, grapefruit juice)

Question 24

What should you ask a patient before switching them from erythromycin?

Answer 24

Ask them what they are using it for because it is not only an antibiotic but it is also used for diabetic gastroparesis