Metaclopramide all are true except –
**Core Concept**
Metoclopramide is a prokinetic agent that acts primarily on the gastrointestinal tract, enhancing gastric emptying and motility. It is a dopamine antagonist that also has serotonin 5-HT4 agonist activity, which contributes to its prokinetic effects.
**Why the Correct Answer is Right**
Metoclopramide exerts its prokinetic effects by blocking dopamine D2 receptors in the gastrointestinal tract, particularly in the area of the chemoreceptor trigger zone (CTZ) and the gastrointestinal tract's motility centers. This blockade leads to increased acetylcholine release, which in turn stimulates the smooth muscle of the gastrointestinal tract to contract and relax in a coordinated manner, enhancing gastric emptying and motility. Additionally, its serotonin 5-HT4 agonist activity increases the release of acetylcholine from the enteric nervous system, further enhancing gastrointestinal motility.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because metoclopramide does indeed increase gastric emptying and motility, as previously discussed.
**Option B:** This option is incorrect because metoclopramide does not significantly affect salivary or pancreatic enzyme secretion.
**Option C:** This option is incorrect because metoclopramide does not have a significant effect on intestinal absorption of nutrients.
**Option D:** This option is incorrect because metoclopramide does not have a significant effect on blood glucose levels.
**Clinical Pearl / High-Yield Fact**
Metoclopramide can cause extrapyramidal side effects such as dystonia, parkinsonism, and tardive dyskinesia due to its central dopamine antagonist effects. These side effects can be managed with anticholinergics or benzodiazepines.
**Correct Answer: D. Metoclopramide does not significantly affect blood glucose levels.**