September 21, 2015 - Pharmacology Gut Motility

Question 1

Gastroparesis

Answer 1

Syndrome of delayed gastric emptying. Symptoms include: early satiety, post-prandial fullness, nausea and vomiting, bloating, and upper abdominal pain.

Question 2

Metroclopramide

Answer 2

A pro-kinetic and anti-emetic.

A dopamine D2-receptor antagonist (D₂RA) and a 5-HT₄-receptor agonist. This increases gastric contraction, pylorus relaxation, and duodenal peristalsis.

Use liquid form whenever possible.

Risk of tardive dyskinesia.

Question 3

Tardive Dyskinesia

Answer 3

A disorder resulting in involuntary, repetitive body movements. “Tardive” means that the involuntary movements have a slow or belated onset. This can be a (sometimes permanent) side effect of metroclopramide.

Question 4

Domperidone

Answer 4

A peripheral D₂RA that does not cross the blood-brain barrier.

As efficacious as metroclopramide in reducing symptoms, but with less CNS side-effects. However, it has a propensity to cause QT prolongation. Because of this, you need to get a baseline ECG and perform follow-up ECGs.

Question 5

Erythromycin

Answer 5

A motilin agonist.

Produces high-amplitude propulsive gastric contractions and is effective when given in IV. When given PO, often results in tachyphylaxis (decrease in effectiveness).

This also has a propensity to cause QT prolongation.

Question 6

Prucolopride

Answer 6

A new-generation highly selective 5HT₄-RA pro-kinetic that accelerates colonic transit in constipation.

It has a 150-fold higher affinity for 5HT₄ receptors than for other receptors in the older drugsm and therefore has significantly minimized risks for side-effects. There is no increased incidence of new cardiac events or QT prolongation.