Lesson 21: Gastrointestinal Motility
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Questions and Answers

What is the primary mechanism of action of bisacodyl?

  • Increases electrolyte and water secretion by the mucosa (correct)
  • Decreases peristalsis through stimulation of enteric nerves
  • Directly stimulates the myenteric plexus
  • Increases gastric emptying rate

Which side effect is commonly associated with stimulant laxatives such as senna?

  • Abdominal cramping (correct)
  • Decreased appetite
  • Constipation
  • Gallbladder issues

In which scenario is the use of senna contraindicated?

  • Patients with bowel obstruction (correct)
  • Terminally ill patients
  • Preparation for digestive assessments
  • Bedridden patients

What is the mechanism of action for bulk laxatives?

<p>They form a bulky hydrated mass that encourages peristalsis. (B)</p> Signup and view all the answers

What pharmacological class does prucalopride belong to?

<p>Serotoninergic agonist (C)</p> Signup and view all the answers

Which laxative type is contraindicated in patients with poor renal function?

<p>Osmotic laxatives (B)</p> Signup and view all the answers

What is a significant use of metoclopramide?

<p>As an antiemetic that also accelerates gastric emptying (D)</p> Signup and view all the answers

Which of the following is true about sodium picosulfate?

<p>It increases peristalsis by stimulating enteric nerves. (C)</p> Signup and view all the answers

What is a common adverse effect associated with osmotic laxatives?

<p>Abdominal cramps (B)</p> Signup and view all the answers

For which group of patients is the use of stimulant laxatives often indicated?

<p>Bedridden patients needing to prevent constipation (B)</p> Signup and view all the answers

Which of the following describes the action of faecal softeners?

<p>They function similarly to a detergent to promote soft stools. (B)</p> Signup and view all the answers

Which agent is considered the first choice for chronic constipation?

<p>Bulk laxatives (C)</p> Signup and view all the answers

Which of the following agents is specifically used for constipated patients with irritable bowel syndrome?

<p>Tegaserod (B)</p> Signup and view all the answers

What is a known adverse reaction associated with bulk laxatives?

<p>Abdominal distension (C)</p> Signup and view all the answers

Which laxative is known for an effect within about one hour?

<p>Osmotic laxatives (D)</p> Signup and view all the answers

What is the action of prokinetic drugs in the GI tract?

<p>They increase the motility of GI smooth muscle. (B)</p> Signup and view all the answers

Which of the following statements about prokinetic drugs is true?

<p>Prokinetic drugs can cross the blood-brain barrier and affect the chemoreceptor trigger zone. (A)</p> Signup and view all the answers

What is the mechanism of action of lubiprostone?

<p>Activates chloride channels in the small intestine. (D)</p> Signup and view all the answers

Naloxegol is primarily indicated for which condition?

<p>Opioid-induced constipation without affecting analgesic properties. (A)</p> Signup and view all the answers

What are the primary side effects associated with loperamide?

<p>Constipation and abdominal cramps. (D)</p> Signup and view all the answers

What is the main consequence of gastrointestinal motility increase during diarrhea?

<p>Loss of electrolytes and increased fluid secretion. (D)</p> Signup and view all the answers

In which scenario should prokinetic drugs be avoided?

<p>Paralytic ileus. (A)</p> Signup and view all the answers

How do antidiarrhoeal agents like opioids function in the treatment of diarrhea?

<p>They inhibit motility in the gastrointestinal tract. (C)</p> Signup and view all the answers

What is the primary role of methyl-naltrexone in treating constipation?

<p>To counteract opioid-induced constipation by blocking peripheral opioid receptors. (A)</p> Signup and view all the answers

Which agent is indicated for treating opioid-induced constipation without affecting the analgesic properties of opioid agonists?

<p>Naloxegol (B)</p> Signup and view all the answers

What is a common adverse reaction associated with the use of loperamide?

<p>Both B and C (C)</p> Signup and view all the answers

What is the primary action of lubiprostone in treating constipation?

<p>Promoting chloride and fluid secretion into the lumen (B)</p> Signup and view all the answers

Which of the following drugs is primarily classified as a peripheral opioid-receptor antagonist?

<p>Methyl-naltrexone (C)</p> Signup and view all the answers

Which condition is not effectively treated by metoclopramide?

<p>Paralytic ileus (A)</p> Signup and view all the answers

What is the primary mechanism of action of opioids as antidiarrhoeal agents?

<p>Inhibiting intestinal motility (C)</p> Signup and view all the answers

What role do electrolyte solutions play in the management of severe acute diarrhea?

<p>Replace lost fluids and electrolytes (C)</p> Signup and view all the answers

What type of drug is indicated for patients with constipation due to opioid use?

<p>Chloride channel-2 activators (A)</p> Signup and view all the answers

What is the primary purpose of osmotic laxatives such as lactulose?

<p>To retain a large volume of fluid in the intestine (D)</p> Signup and view all the answers

Which laxative type is characterized by water-attracting polymers that improve fecal volume?

<p>Bulk laxatives (D)</p> Signup and view all the answers

What is a common adverse effect associated with the use of bulk laxatives?

<p>Flatulence and abdominal distension (C)</p> Signup and view all the answers

Which laxative agent can lead to impaired absorption of liposoluble vitamins?

<p>Fecal softeners (A)</p> Signup and view all the answers

What mechanism do stimulant purgatives like senna utilize to function effectively?

<p>Stimulating contractions of the intestinal smooth muscle (B)</p> Signup and view all the answers

Osmotic laxatives are contraindicated in which scenario?

<p>Patients with poor renal function (C)</p> Signup and view all the answers

Which mechanism of action describes how fecal softeners work?

<p>Promoting the production of soft stools and mild stimulation (B)</p> Signup and view all the answers

What is an effect of drugs that decrease motility, such as antidiarrheal medications?

<p>Reduce the frequency of bowel movements (C)</p> Signup and view all the answers

What effect do stimulant laxatives like bisacodyl and sodium picosulfate have on the intestines?

<p>They stimulate water and electrolyte secretion. (B)</p> Signup and view all the answers

For which reason is senna primarily utilized as a stimulant laxative?

<p>To provide relief in temporally constipated patients. (B)</p> Signup and view all the answers

What is a significant limitation associated with the use of senna in some patients?

<p>It can cause dependency with long-term use. (B)</p> Signup and view all the answers

How does the mechanism of action of prucalopride differ from that of typical stimulant laxatives?

<p>It acts on serotonin receptors to enhance GI motility. (C)</p> Signup and view all the answers

What common side effect may occur with the use of stimulant laxatives?

<p>Abdominal cramping. (C)</p> Signup and view all the answers

Which of the following is a contraindication for the use of stimulant laxatives like senna?

<p>Obstruction of the bowel. (B)</p> Signup and view all the answers

What is the role of metoclopramide in treating gastrointestinal issues?

<p>To increase gastric emptying and motility. (A)</p> Signup and view all the answers

What patient group is most likely to benefit from the use of prucalopride?

<p>Patients who have not responded to other laxatives. (C)</p> Signup and view all the answers

Flashcards

Purgatives

Drugs that increase the speed of food passage through the intestines, leading to more frequent bowel movements.

Prokinetic drugs

Drugs that increase the movement of the smooth muscle in the gastrointestinal tract without causing diarrhea.

Antidiarrhoeal drugs

Drugs that slow down the movement of the gastrointestinal tract, used for treating diarrhea.

Antispasmodic drugs

Drugs that reduce muscle tension in the gastrointestinal tract, mainly targeting spasms.

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Bulk laxatives

Laxatives that work by adding bulk to the stool, making it easier to pass.

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Osmotic laxatives

Laxatives that work by attracting water into the intestines, increasing stool volume and promoting bowel movements.

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Faecal softeners

Laxatives that soften the stool, making it easier to pass.

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Stimulant purgatives

Laxatives that stimulate the muscles in the intestines to contract, promoting bowel movements.

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Peripheral opioid-receptor antagonist

A drug that blocks the effects of opioids in the intestines, reducing their side effect of constipation.

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What is the mechanism of action of stimulant laxatives?

Stimulant laxatives increase water secretion in the intestines and stimulate the enteric nerves to increase peristalsis, leading to bowel movements.

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How does Bisacodyl work when given as a suppository?

Bisacodyl can be taken orally or as a suppository. Suppository application directly stimulates the rectal mucosa, causing a bowel movement within 15-30 minutes.

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How do Senna and Dantron work?

Senna and Dantron directly stimulate the myenteric plexus, which encourages increased peristalsis and bowel movements.

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What are the indications for using stimulant laxatives?

Stimulant laxatives can be used for temporary constipation, especially for bedridden patients or those with difficulty defecating.

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What are potential risks of overusing stimulant laxatives?

Overuse of stimulant laxatives can lead to dependence and a weakened colon, making it difficult to pass stool naturally.

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What is the general mechanism of action for prokinetic drugs?

Prokinetic drugs increase GI cholinergic activation, speeding up stomach emptying and peristalsis in the intestines.

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How do Serotonin agonists work?

Serotonin agonists, like Prucalopride and Tegaserod, increase cholinergic activity by stimulating 5-HT4 receptors.

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What is the mechanism of action and key feature of Domperidone?

Domperidone is a D2 antagonist that increases GI motility by indirectly influencing cholinergic activity. It does not cross the blood-brain barrier.

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What are bulk laxatives?

Bulk laxatives work by absorbing water and increasing stool volume, leading to smoother bowel movements. They're best for chronic constipation because of their slow, gentle action.

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How do osmotic laxatives work?

Osmotic laxatives draw water into the intestines, increasing stool volume and speeding up bowel movements. They work quickly, typically within an hour.

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What is the function of faecal softeners?

Faecal softeners act like detergents, making the stool softer and easier to pass. They take longer to work than osmotic laxatives.

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How do stimulant laxatives work?

Stimulant laxatives directly stimulate the muscles in the intestines to contract, increasing bowel movements. They can have a more rapid effect, but overuse can lead to dependence.

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What are laxatives and how do they work?

Laxatives are used to treat constipation by helping the body eliminate waste more easily. They work through different mechanisms, each with its own speed and potential side effects.

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When should you use laxatives?

The effectiveness and safety of laxatives depend on the individual and the underlying reason for constipation. Always consult a healthcare professional before using laxatives.

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What is ispaghula husk and how does it work?

Ispaghula husk, a common bulk laxative, works by absorbing water and increasing stool volume. It's often the first choice for chronic constipation as it has a gentler action and doesn't cause dependence.

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How does lactulose work?

Lactulose is an osmotic laxative that draws water into the intestines, leading to increased stool volume and bowel movements. It works quickly, usually within an hour.

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What does Bisacodyl do as a suppository?

Bisacodyl, when given as a suppository, directly stimulates the rectal mucosa, causing a bowel movement typically within 15 to 30 minutes.

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What do Prokinetic Drugs do?

Prokinetic drugs work by increasing cholinergic activity in the gastrointestinal tract. This speeds up stomach emptying and increases peristalsis in the intestines, moving food and waste more effectively.

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Explain Domperidone's mechanism.

Domperidone is a D2 antagonist that indirectly increases GI motility by influencing cholinergic activity. It does not cross the blood-brain barrier, meaning it primarily targets the digestive system.

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What are the indications for stimulant laxatives?

Stimulant laxatives are effective in treating temporary constipation and can be particularly helpful for bedridden patients or those who struggle with defecation. They are not meant for long-term use.

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What are the risks of overusing stimulant laxatives?

Overuse of stimulant laxatives can lead to dependence and can weaken the colon, making it difficult to have normal bowel movements. They should always be used under the guidance of a healthcare professional.

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Lubiprostone: What is it?

A drug that works by activating chloride channel-2 in the small intestine, leading to increased fluid secretion and softening of stools. It improves gut motility and is used for constipation due to opioids, IBS, and in cases where non-drug treatment has failed.

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Naloxegol: How does it work?

A drug that blocks the effects of opioid medications specifically in the intestines, alleviating opioid-induced constipation without affecting the analgesic properties of opioids in the brain.

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Methylnaltrexone: What is it?

A drug that blocks the effects of opioids specifically in the intestines, treating opioid-induced constipation.

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What is the underlying mechanism behind diarrhea?

This involves an increase in the speed of movement of the gastrointestinal (GI) tract, coupled with increased secretion and decreased absorption of fluids. This leads to a loss of water and electrolytes, particularly sodium (Na+).

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Loperamide: What are its characteristics?

A drug that reduces the frequency of abdominal cramps associated with diarrhea, slows the passage of stool, and shortens the duration of the illness. Its selective and local action in the GI tract allows for effective treatment without significant systemic side effects. It is often the preferred choice for travelers' diarrhea.

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What are the potential side effects of opioid-based antidiarrheal medications?

These adverse events can occur due to the drug's action on the central nervous system and include constipation, abdominal cramps, drowsiness, dizziness, and in severe cases, complete loss of intestinal motility (paralytic ileus). These drugs should be avoided in young children.

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What is Paralytic Ileus, and why are prokinetic drugs ineffective?

This condition involves inadequate movement of food through the digestive tract, potentially leading to blockage. Medications that increase GI motility are often not effective in treating this condition.

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When are antidiarrheal medications specifically indicated for conditions like IBS and diverticular disease?

These drugs are used to treat conditions like irritable bowel syndrome (IBS) and diverticular disease. Their mechanism of action involves slowing down the movement of the digestive tract, reducing stomach acidity and reducing muscle spasms in the intestines.

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Study Notes

Lesson 21: Gastrointestinal Motility

  • This lesson covers gastrointestinal motility, focusing on drugs that alter it.
  • Agents that affect GI tract motility include purgatives, prokinetic drugs, antidiarrhoeal drugs, and antispasmodic drugs.

Drugs Altering GI Tract Motility

  • Purgatives: accelerate food passage through the intestines.
  • Prokinetic drugs: increase GI smooth muscle motility without causing purgation.
  • Antidiarrhoeal drugs: decrease GI motility.
  • Antispasmodic drugs (spasmolytics): decrease smooth muscle tone.

Laxative Agents

  • Purgatives/laxative agents include:
    • Bulk laxatives (e.g., ispaghula husk): first choice for slow action, work by attracting water to form a bulky mass, improving stool consistency and peristalsis. Takes 1-3 days to work. First choice in chronic constipation and long-term treatment. Side effects include flatulence and abdominal distension, and potential bowel obstruction in patients with intestinal pathologies.
    • Osmotic laxatives (e.g., lactulose): creates osmotic load, retaining fluid in the intestine, speeding up transit and causing colon distension. Works within 1 hour. Side effects include abdominal cramps, and it's important to avoid use in young children and in patients with poor kidney function.
    • Faecal softeners (e.g., docusate): acts similarly to a detergent, promoting soft stools and weak stimulant activity. Side effects include impaired absorption of fat-soluble vitamins (A, D, E).
    • Stimulant purgatives (e.g., senna): directly stimulates the myenteric plexus, increasing peristalsis. Usually used for temporary constipation.

Prokinetic Drugs

  • Mechanism of action: stimulate and improve intestinal transit by increasing GI cholinergic activation, increasing stomach emptying rate and intestinal peristalsis.
  • Agonists of 5-HT4 receptor: Prucalopride and tegaserod (used when other treatments fail, such as for irritable bowel syndrome (IBS) constipation).
  • D2 antagonists (e.g., domperidone) and metoclopramide: Primarily used as antiemetics but also increase GI motility (indirectly and directly). Metoclopramide crosses the blood-brain barrier (BBB), whereas domperidone does not.
  • Other agents (e.g., lubiprostone, naloxegol, methylnaltrexone): lubiprostone activates chloride channels to increase fluid and chloride secretion, naloxegol is a µ-opioid receptor antagonist that prevents penetration into the central nervous system (CNS) in constipation. Methylnaltrexone is a peripheral opioid receptor antagonist and used for opioid-induced constipation.

Antidiarrhoeal Agents

  • Inhibitors of intestinal motility (e.g., loperamide): effective in traveler's diarrhea and decreases frequency and duration due to its selective and local action in the GI tract; slows down transit rate. Side effects include complete loss of bowel function (paralytic ileus) if misused.
  • Muscarinic antagonists (e.g., atropine, hyoscyamine, propantheline, dicycloverine): rarely used as they affect other systems (anticholinergic effect) and have side effects such as dry mouth, blurry vision, and urinary retention.
  • Adsorbents (e.g., kaolin, pectin, chalk, charcoal, methylcellulose): might absorb microorganisms or toxins from the intestine, and coat/protect the intestinal mucosa.
  • Other agents (e.g., racecadotril, anandamides): racecadotril is a prodrug of thiorphan, an enkephalinase inhibitor; prevents degradation of enkephalins to manage diarrhea. Anandamides are cannabinoid receptor agonists that reduce intestinal motility.

Treatment of Chronic Bowel Diseases

  • IBS (irritable bowel syndrome):
    • Symptomatic treatment with a low-residue diet, loperamide (for diarrhea), or ispaghula husk (for constipation).
    • 5-HT treatments (alosetron, ramosetron) decrease gut motility; and tegaserod stimulates GI motility. -Other treatments like eluxadoline (mixed μ/κ opioid receptor agonist and δ-receptor antagonist) are used. -Linaclotide stimulates secretion of HCO3- and Cl-, increasing intestinal fluid and more rapid intestinal transit (guanylate cyclase-C agonist).
  • IBD (inflammatory bowel diseases) includes Ulcerative Colitis and Crohn's disease:
    • Glucocorticoids: potent anti-inflammatory agents, primarily used for short-term treatment of acute attacks. Includes Prednisolone, and Budesonide
    • Aminosalicylates: used to maintain remission, includes Sulfasalazine which breaks down into sulfapyridine and 5-ASA; 5-ASA is not absorbed but sulfapyridine is and is related to blood dyscrasia, hepatitis, and hypersensitivity.
    • Immunosuppressants used for severe diseases like Methotrexate, Cyclosporine, Tacrolimus, Azathioprine, and 6-mercaptopurine.
    • Sodium cromoglycate for allergic symptoms.
    • Biologic therapy:
      • Infliximab, vedolizumab, and ustekinumab: monoclonal antibodies targeting various inflammatory components. These are for moderate to severe IBD not responding to standard treatment.

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Lesson 21: Gastrointestinal Motility & Chronic Bowel Disease PDF

Description

This quiz focuses on gastrointestinal motility, exploring how various drugs affect it. Key topics include purgatives, prokinetic drugs, antidiarrhoeal agents, and antispasmodic medications. Test your knowledge on the mechanisms and effects of these pharmacological agents.

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