17 topics with brief breakdowns: definitions, key facts, and class questions.
This section focuses on the pharmacology of the gastrointestinal tract, one of the most comprehensive and clinically significant topics. Here, we analyze drugs that regulate motility, secretion, and digestive processes.
The material covers all key groups. We will examine drugs affecting secretion (antacids, H2-receptor blockers, proton pump inhibitors, antimuscarinics [M-cholinoblockers], gastrointestinal cytoprotectors) and motility (emetics and antiemetics, prokinetics, laxatives, antidiarrheals). Medications for the liver, biliary tract, and pancreas are covered separately: cholagogues, cholelitholytic agents, and hepatoprotective drugs, as well as enzymes and proteolysis inhibitors. The picture is completed by carminatives, antifoaming agents, and probiotics.
What is most frequently asked in class? During seminars and exams, instructors strictly evaluate the knowledge of the mechanisms of action of proton pump inhibitors and prokinetics. Favorite questions concern the sites of action of antiemetics and laxatives, as well as the pharmacodynamics of hepatoprotectants and enzyme preparations. Understanding these topics is your foundation for future practice in internal medicine and gastroenterology.
What is the anatomical structure of the vomiting reflex and where is the trigger zone located?
The central component is the vomiting center in the medulla oblongata. The chemoreceptor trigger zone is located on the floor of the fourth ventricle. It is this zone that detects chemical substances in the blood and cerebrospinal fluid.
Why is metoclopramide contraindicated in suspected GI perforation?
Metoclopramide has a pronounced prokinetic effect — it actively stimulates propulsive gastric motility. In ulcers, bleeding, or perforations, enhanced peristalsis can lead to a sharp deterioration in the patient's condition.
Why is sodium bicarbonate unsuitable for long-term treatment?
It causes a rapid release of carbon dioxide, which leads to gastric distension and the "rebound" syndrome (secondary hypersecretion). Additionally, its absorption threatens the development of systemic alkalosis.
What is the difference between cimetidine and ranitidine in terms of drug interactions?
Cimetidine inhibits cytochrome P450 and microsomal oxidation, slowing down the metabolism of other drugs, whereas ranitidine does not affect the metabolism of concomitant medications.
Why does hydrochloric acid secretion recover slowly after taking PPIs?
Proton pump inhibitors effect an irreversible blockade of the H+/K+-ATPase enzyme. Consequently, the resumption of acid production is only possible after the de novo synthesis of new enzyme molecules, which takes time.
Why are non-selective antimuscarinics currently rarely used for peptic ulcer disease?
Due to their low selectivity of action, they cause pronounced systemic side effects such as dry mouth, mydriasis, accommodation paralysis, and tachycardia.
Master the entire topic in the «Pharmacology» course
This is a summary. The course covers everything tested in classes and exams.
5,304 pages of study guides on all topics
Assignments and quizzes after every topic — just like in a colloquium