Mekanisme obat-obat sistem saluran cerna

Summary

This transcript delves into pharmacological treatments for gastrointestinal disorders, focusing on prokinetic drugs that enhance motility in the digestive tract. It explains the mechanisms of action of various drugs like cisapride, domperidone, and metoclopramide. The discussion extends to antiemetics, such as ondansetron and domperidone, which block certain receptors to prevent vomiting. Additionally, the transcript explores treatments for diarrhea, constipation, and acid reflux, including the use of antidiarrheals, laxatives, H2 antagonists, proton pump inhibitors, antacids, and misoprostol. Overall, it provides an in-depth overview of the pharmacological management of gastrointestinal issues.

Takeaways

• 😀 Prokinetic drugs enhance gastrointestinal motility and are used to treat gastroparesis and motility disorders. They improve the frequency and strength of peristaltic contractions without disturbing the rhythm.
• 😀 Prokinetic medications like cisapride, domperidone, and metoclopramide work by affecting neurotransmitter systems in the gut, such as serotonin and dopamine receptors.
• 😀 The enteric nervous system, particularly the cholinergic system, plays a key role in regulating peristaltic movements by releasing acetylcholine, which activates muscarinic receptors in the gut muscles.
• 😀 Serotonin, released from enterochromaffin cells, activates serotonin receptors in the gut, which in turn excites cholinergic neurons, leading to the release of acetylcholine and promoting smooth muscle contractions.
• 😀 Medications like domperidone and metoclopramide act as dopamine D2 receptor antagonists, whereas cisapride and tegaserod function as serotonin agonists, both of which enhance peristalsis.
• 😀 Antiemetic drugs target receptors like dopamine D2, serotonin 5-HT3, muscarinic, and histamine H1 to prevent or reduce vomiting by blocking these pathways in the brain's vomiting center.
• 😀 Ondansetron is a serotonin 5-HT3 antagonist that prevents nausea and vomiting by blocking serotonin receptors in the gut and the brain.
• 😀 Domperidone not only acts as a prokinetic but also as an antiemetic by blocking dopamine receptors in the vomiting center of the brain.
• 😀 Drugs like loperamide and diphenoxylate, which are used to treat diarrhea, work as opioid receptor agonists in the gut. They slow down peristalsis by inhibiting acetylcholine release.
• 😀 Antidiarrheal treatments include adsorbents like kaolin pectin and bismuth subsalicylate, which bind toxins and bacteria, as well as antisecretory agents that help reduce fluid loss in the intestines.
• 😀 Laxatives used for constipation can be classified into softeners, bulk-forming agents, osmotic agents, and stimulant cathartics, each promoting bowel movements in different ways.
• 😀 Proton pump inhibitors (PPIs) like omeprazole and pantoprazole irreversibly inhibit the proton pump in stomach cells, reducing acid secretion. Antacids neutralize stomach acid through chemical reactions, with combinations of magnesium and aluminum hydroxide to minimize side effects like diarrhea or constipation.
• 😀 Misoprostol, a prostaglandin analog, increases mucous and bicarbonate secretion to protect the stomach lining, but it can induce uterine contractions and is contraindicated in pregnancy.
• 😀 Sucralfate forms a protective barrier on damaged stomach lining, helping to heal ulcers by binding to ulcerated tissue and preventing further injury.

Q & A

What are prokinetic drugs, and how do they affect the gastrointestinal system?

Prokinetic drugs, such as cisapride, tegaserod, domperidone, and metoclopramide, enhance gastrointestinal motility by increasing the frequency and strength of muscle contractions in the digestive tract. They do not disrupt the rhythm of these contractions, meaning the movement is stronger but remains coordinated.

How does the autonomic nervous system regulate gastrointestinal motility?

Gastrointestinal motility is regulated by the autonomic nervous system, specifically the cholinergic system. Acetylcholine, released by cholinergic neurons, activates muscarinic receptors (M3) in the digestive tract, leading to muscle contractions. This process is triggered by serotonin, which excites cholinergic neurons.

What role do dopamine and serotonin play in regulating gastrointestinal motility?

Dopamine and serotonin are key neurotransmitters involved in gastrointestinal motility. Dopamine, through D2 receptors, inhibits motility, while serotonin, particularly through 5-HT4 receptors, promotes motility by enhancing acetylcholine release, which increases muscle contractions in the digestive tract.

How do prokinetic drugs, like domperidone and metoclopramide, work?

Domperidone and metoclopramide act as dopamine D2 receptor antagonists. By blocking these receptors in the gastrointestinal tract, they enhance the release of acetylcholine, promoting stronger and more frequent contractions in the digestive muscles.

What is the mechanism of action for serotonin agonists like cisapride?

Serotonin agonists like cisapride activate 5-HT4 receptors in the gastrointestinal tract, which enhances acetylcholine release from cholinergic neurons. This results in increased peristaltic contractions, improving motility in the digestive system.

What are antiemetic drugs, and how do they function?

Antiemetic drugs, such as ondansetron, domperidone, and scopolamine, prevent or alleviate nausea and vomiting by blocking specific receptors involved in the vomiting reflex. Ondansetron blocks serotonin 5-HT3 receptors, while domperidone blocks dopamine D2 receptors, and scopolamine blocks muscarinic receptors.

How does the vomiting reflex work?

The vomiting reflex is triggered by stimuli from the gastrointestinal tract, vestibular system, and other areas, which send signals to the vomiting center in the brainstem. This center coordinates the motor responses that result in vomiting. These stimuli activate specific receptors like dopamine D2, serotonin 5-HT3, and histamine H1.

What is the role of loperamide in gastrointestinal treatments?

Loperamide is an opioid derivative used to treat diarrhea. It works by activating opioid receptors (mu receptors) in the gastrointestinal tract, which inhibits acetylcholine release, decreasing motility and allowing for more water absorption in the intestines.

What types of drugs are used to treat constipation, and how do they work?

Drugs used to treat constipation include softeners like docusate, bulk-forming agents like calcium polycarbophil, osmotic agents like lactulose, and stimulant laxatives like bisacodyl. These drugs either soften stool, increase stool volume, draw water into the intestines, or stimulate the colon to promote bowel movements.

How do proton pump inhibitors (PPIs) like omeprazole and pantoprazole work?

Proton pump inhibitors (PPIs) like omeprazole and pantoprazole block the proton pump (H+/K+ ATPase) in parietal cells, which reduces the production of stomach acid. This inhibits the final step of hydrochloric acid formation, helping manage conditions like acid reflux and gastric ulcers.