Gastrointestinal Motility and Laxatives

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Questions and Answers

What is the primary mechanism of action of bisacodyl as a stimulant laxative?

Increases electrolyte and water secretion by the mucosa (correct)

Inhibits enteric nerve stimulation

Decreases bowel peristalsis

Increases gastric acid secretion

Which of these is an indication for the use of stimulant laxatives such as senna?

Post-operative nausea

Severe dehydration

Chronic gastrointestinal bleeding

Preparing for digestive assessments (correct)

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

Hypotension

Acid reflux

Drowsiness

Abdominal cramping (correct)

Which of the following drugs is primarily used as an antiemetic but also increases gastrointestinal motility?

Domperidone Signup and view all the answers

What should be avoided when using stimulant laxatives?

Overuse and dependence Signup and view all the answers

What condition is a contraindication for the use of stimulant laxatives?

Obstruction of the bowel Signup and view all the answers

What is the role of serotonin in gastrointestinal motility according to the content?

Increases cholinergic activity Signup and view all the answers

Which of the following laxatives acts as an irritant purgative and has restricted use due to its carcinogenic effects?

Senna Signup and view all the answers

Which type of laxative is considered the first choice for chronic constipation?

Bulk laxatives Signup and view all the answers

What mechanism of action do osmotic laxatives have?

They create an osmotic load that retains fluid in the intestine. Signup and view all the answers

Which statement correctly describes the action of Lubiprostone?

It activates chloride channels to promote fluid secretion. Signup and view all the answers

Which of the following laxatives is known to potentially cause obstruction in patients with intestinal pathologies?

Bulk laxatives Signup and view all the answers

Which laxative type's effect can typically be seen within about an hour?

Osmotic laxatives Signup and view all the answers

What is a common adverse drug reaction associated with D2 blockers in the CNS?

Extrapyramidal symptoms Signup and view all the answers

Which of the following drugs is an example of a peripheral opioid-receptor antagonist?

Methylnaltrexone Signup and view all the answers

What is a common adverse effect of faecal softeners?

Impaired absorption of liposoluble vitamins Signup and view all the answers

In managing severe acute diarrhoea, which is NOT a recommended treatment option?

Restricting all fluids completely Signup and view all the answers

Antidiarrhoeal drugs typically have what effect on gastrointestinal motility?

Decrease motility to reduce bowel movements Signup and view all the answers

What is a characteristic feature of stimulant purgatives?

They work rapidly, typically within an hour. Signup and view all the answers

How does Naloxegol help in the treatment of opioid-induced constipation?

It counteracts reduced GI motility without affecting analgesia. Signup and view all the answers

Antispasmodic drugs primarily function by doing what?

Decreasing smooth muscle tone Signup and view all the answers

What category of agents is primarily responsible for reducing intestinal motility in diarrhoea treatment?

Inhibitors of intestinal motility Signup and view all the answers

What should be avoided when treating young patients with opioids?

Complete loss of intestinal motility Signup and view all the answers

What is a potential side effect of Loperamide?

Constipation Signup and view all the answers

Study Notes

Lesson 21: Gastrointestinal Motility

Gastrointestinal system motility is affected by a variety of medications.
Drugs that alter GI tract motility include purgatives, which accelerate food passage through the intestines; this may include prokinetic drugs, which increase motility without causing purgation; antidiarrheal drugs, which reduce motility; and antispasmodic/spasmolytic drugs, which reduce smooth muscle tone.

Laxative Agents

Purgatives or laxatives include bulk laxatives (e.g., ispaghula husk), osmotic laxatives (e.g., lactulose), faecal softeners (e.g., docusate), and stimulant purgatives (e.g., senna).
Bulk laxatives work by increasing fecal volume and consistency, promoting peristalsis, taking 1-3 days to act.
Osmotic laxatives work by retaining fluid in the intestine, speeding up transit and causing distension, which has an effect within one hour.
Faecal softeners act similarly to detergents in the gut, promoting soft stool production and a weak stimulant laxative activity. They can affect the absorption of fat-soluble vitamins (A,D,E).
Stimulant laxatives (bisacodyl, sodium picosulfate, senna, and dantron) increase electrolyte and water secretion and peristalsis via stimulation of enteric nerves. Bisacodyl is often administered rectally. Senna and dantron are anthraquinone derivatives.
Overuse of laxatives can cause dependence and lead to an atonic colon.

Prokinetic Drugs

Prokinetic drugs stimulate GI cholinergic activation, increasing stomach emptying rate and peristalsis/transit rate.
These drugs may include serotonin agonists (e.g., prucalopride, tegaserod), dopamine decreasers (e.g., antidopaminergics).
D₂ antagonists (e.g., domperidone, metoclopramide). Some are antiemetics (prevent nausea & vomiting). Some may cross the blood-brain barrier.
Other agents (e.g., lubiprostone) stimulate chloride and fluid secretion for softer stools.
Naloxegol and methylnaltrexone are opioid receptor antagonists that combat opioid-induced constipation but generally don't affect pain management.

Antidiarrheal Agents

Antidiarrheal agents can include inhibitors of intestinal motility
Opioids (loperamide) have a selective and local effect in the GI tract, reducing abdominal cramps and passage of feces. They have enterohepatic cycling.
Muscarinic antagonists (e.g., atropine, hyoscine, propantheline, dicycloverine) are rarely used due to anticholinergic side effects.
Absorbents (e.g., kaolin, pectin, chalk, charcoal) are believed to adsorb microorganisms or toxins.
Other agents (e.g., racecadotril) inhibit enkephalinase, reducing intestinal secretion.
Anandamide is a cannabinoid receptor agonist that reduces intestinal motility and diarrhea.

Treatment of Chronic Bowel Disease

Chronic bowel disease comprises irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD).
- IBS includes diarrhea-predominant (IBS-D), constipation-predominant (IBS-C), and mixed-symptom (IBS-M). Aetiology is uncertain but may involve gut-brain axis, visceral hypersensitivity, and stress.
  - Treatment includes a low-residue diet, loperamide for diarrhea, and laxatives if needed for constipation.
- 5-HT treatments include antagonists (alosetron, ramosetron), which decrease gut motility, and agonists (tegaserod) which stimulate motility.
- Other treatments such as eluxadoline, a mixed μ/κ opioid receptor agonist and δ-receptor antagonist, act on peripheral receptors to reduce colonic motility but improve pain/diarrhea. Linaclotide stimulates secretion leading to rapid intestinal transit.
IBD subtypes include ulcerative colitis or Crohn's disease.
- Treatment includes glucocorticoids (prednisolone or budesonide), or via suppositories or enemas; aminosalicyates (sulfasalazine) to inhibit inflammation; and immunomodulators or biologics like infliximab, vedolizumab or ustekinumab.

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Description

This quiz explores the factors affecting gastrointestinal motility and the different types of laxative agents. Learn about purgatives, prokinetic drugs, and other medications that influence the digestive system. Test your knowledge on how these agents work and their effects on the GI tract.