Gastrointestinal Motility Disorders Quiz

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Questions and Answers

What primarily initiates the act of vomiting?

Interaction between the vomiting center and chemoreceptor trigger zone (correct)

Regulation of blood pressure

Contraction of abdominal muscles alone

Activation of the digestive enzymes

Which of the following conditions is not commonly associated with prolonged and severe vomiting?

Dehydration

Hyperlipidemia (correct)

Alkalosis

Hypokalemia

Which part of the brain contains the vomiting center?

Hypothalamus

Cerebral cortex

Cerebellum

Dorsal portion of the lateral reticular formation of the medulla (correct)

What physical changes occur during the vomiting act?

Compression of the stomach through simultaneous contraction of diaphragm and abdominal muscles Signup and view all the answers

During nausea prior to vomiting, which of the following is typically NOT experienced?

Increased appetite Signup and view all the answers

Which of these must be coordinated to successfully expel gastric contents during vomiting?

Vagal efferent nerve fibers and diaphragm contractions Signup and view all the answers

Which situation is commonly cited as a cause of vomiting?

CNS infection or increased pressure in CNS Signup and view all the answers

Which condition is NOT commonly associated with gastric hypomotility?

Gallbladder disease Signup and view all the answers

What physiological change is NOT a response to prolonged vomiting?

Hypercalcemia Signup and view all the answers

What is a potential serious side effect of Metoclopramide that requires a boxed warning?

Tardive dyskinesia Signup and view all the answers

What mechanism does Metoclopramide use to exert its antiemetic effect?

Dopaminergic antagonism at D2 receptors Signup and view all the answers

Which symptom may be caused by gastric hypomotility?

Intense substernal pain Signup and view all the answers

Which drug is associated with gastrointestinal motility stimulation?

Cisapride Signup and view all the answers

Which side effect is most commonly associated with 5HT3 receptor antagonists?

Headache Signup and view all the answers

What is a serious side effect of cannabinoids used as antiemetics?

Hallucinations Signup and view all the answers

Which drug is used as a prokinetic agent to stimulate gut motor function?

An undisclosed agent Signup and view all the answers

What condition is pyridoxine indicated for?

Radiation sickness Signup and view all the answers

Which mechanism is believed to potentially underlie the antiemetic effects of corticosteroids?

Blocking prostaglandins Signup and view all the answers

Which of the following agents can lead to extrapyramidal side effects?

Droperidol Signup and view all the answers

Lorazepam and Alprazolam are primarily indicated for which type of vomiting?

Cytotoxic drug induced vomiting Signup and view all the answers

Which receptor antagonist is specifically indicated for high-dose cytotoxic drug prophylaxis?

Substance P/neurokinin-1 antagonist Signup and view all the answers

Which substance is contraindicated for induced vomiting?

Alkali substances Signup and view all the answers

Which drug from the dopamine receptor antagonists has antiemetic properties?

Haloperidol Signup and view all the answers

What is a primary indication for using Scopolamine?

Motion sickness Signup and view all the answers

Which of the following is classified as a serotonin 5HT3 receptor antagonist?

Palonosetron Signup and view all the answers

What condition is commonly treated with antihistaminics like Diphenhydramine?

Motion sickness Signup and view all the answers

Which of the following substances is NOT traditionally used as an emetic due to its side effects?

Copper sulfate Signup and view all the answers

What mechanism does Apomorphine employ to induce vomiting?

Dopamine receptor stimulation Signup and view all the answers

Which receptor type does Aprepitant target in the treatment of nausea?

Substance P/Neurokinin-1 receptors Signup and view all the answers

Which category does Ondansetron belong to?

Serotonin 5HT3 receptor antagonists Signup and view all the answers

What type of drug is Lorazepam classified as in the context of treating nausea and vomiting?

Benzodiazepine Signup and view all the answers

Study Notes

Gastrointestinal Motility Disorders: Pharmacotherapy

Nausea and Vomiting:
- Vomiting is a complex physiological process involving the GI tract and nervous system, often preceded by nausea and retching.
- Vomiting center (VC) is located in the medulla, interacting with chemoreceptor trigger zone (CTZ), afferent nerves from the gut, the vestibular system, and intracranial pressure receptors.
- Vomiting is preceded by a prodrome, including nausea, cold sweats, pupillary dilation, tachycardia, and salivation.
- Vomiting action involves relaxation of the proximal stomach, longitudinal contraction of the esophagus, and pulling the proximal stomach into the thorax, evacuating the upper small intestine into the stomach via retrograde giant contraction, while emptying the lower intestines into the colon. This is caused by the compression of the stomach through simultaneous contraction of the diaphragm and abdominal muscles.
- Conditions related to vomiting include motion sickness, pregnancy, CNS infection, radiation/chemotherapy, post-operative conditions, GI irritation, and other GI problems, psychiatric disorders, and chemical substances.
- Prolonged or severe vomiting can lead to hypochloremia, hypokalemia, alkalosis, and dehydration, which are dangerous, especially in vulnerable populations.
Emetic Drugs:
- Ipecac syrup irritates the gastric mucosa and causes emesis.
- Apomorphine is a dopamine-like drug that stimulates D2 receptors in the CTZ to cause emesis.
- Hypertonic salt solutions, antimon potassium, copper sulfate, and zinc sulfate have emetic effects but are less commonly used due to side effects.
Drugs used in the treatment of Nausea and Vomiting:
- Muscarinic receptor antagonists (e.g., scopolamine)
- Histamine H1 receptor antagonists (e.g., cyclizine, diphenhydramine, dimenhydrinate, cinnarizine, doxylamine ,meclizine , promethazine)
- Dopamine receptor antagonists (e.g., phenothiazines, butyrophenones, domperidone, metoclopramide )
- Serotonin 5HT3 receptor antagonists (e.g., ondansetron, granisetron, tropisetron)
- Cannabinoids (e.g., tetrahydrocannabinol, nabilone)
- Pyridoxine
- Corticosteroids (e.g., dexamethasone)
- Benzodiazepines (e.g., lorazepam)
- Substance P/Neurokinin-1 receptor antagonists (e.g., aprepitant)
Prokinetic Agents:
- Drugs that stimulate gut motor function, useful in hypermotility patients.
- Increase lower esophageal sphincter pressures, helpful for Gastroesophageal Reflux Disease.
- Reduce gastric fluid volume, decreasing risk of aspiration pneumonitis.
Gastric Hypomotility:
- Delayed emptying of stomach contents in conditions like diabetic neuropathy, anorexia nervosa, achlorhydria, and post-operative gastric surgery.
- Conditions like emergency surgery, full stomach, hiatus hernia, and esophageal reflux require increased gastric motility.
Diarrhea:
- Diarrhea is an abnormal increase in stool frequency, weight, and liquidity caused by many GI disorders (infectious or non-infectious).
- Common types include malabsorptive, maldigestive, and secretory diarrhea.
- Acute diarrhea is usually infectious and self-limiting; drug therapy is rarely needed. Treatment involves electrolyte replacement.
- Chronic diarrhea may be caused by conditions like irritable bowel syndrome (IBS) or inflammatory bowel disease (IBD) .
- Use of antidiarrheals may be safe in mild-to-moderate acute diarrhea, but should not be used in bloody diarrhea, high fever, or systemic toxicity, as they can worsen underlying conditions.
Antidiarrheal Agents:
- Antimotility agents (e.g., opioids, diphenoxylate with atropine, loperamide)
- Adsorbents (e.g., kaolin, pectin, aluminum silicate, methylcellulose)
- Agents that modify fluid and electrolyte transport (e.g., NSAIDs, bismuth subsalicylate)
- Octreotide, a synthetic somatostatin analogue, is effective in higher doses for treating diarrhea due to GI neuroendocrine tumors, vagotomy, dumping syndrome, short bowel syndrome, and AIDS.
- Other agents like antimicrobial drugs and bacterial replacement (e.g., Lactobacillus acidophilus, Saccharomyces boulardii) may be useful in specific cases.
Constipation:
- Inability to have stool frequently, sensation of incomplete evacuation, hard stool, difficulty defecating, flatulence, bloating, and abdominal pain.
- Factors like diet, physical activity, and use of certain medications affect constipation.
- Laxatives should be used judiciously and for a limited duration.
- Analgesics, antacids, anticholinergics, antidiarrheals, antiparkinsonian drugs, barium sulfate, clonidine, diuretics, antihistamines, and ganglion-blocking agents can cause constipation.
Laxative Drugs:
- Bulk-forming agents (e.g., psyllium seed, methylcellulose) swell in the intestine to increase stool bulk and soften stools.
- Stool surfactant agents (e.g., docusate sodium, docusate potassium) promote water absorption into stool, softening it.
- Stimulant laxatives (e.g., bisacodyl, senna glycosides) stimulate bowel movements through increased intestinal motility, sometimes causing abdominal cramps.
- Osmotic laxatives (e.g., lactulose, magnesium hydroxide, sodium phosphate) retain water in the intestine, increasing stool volume.
Treatment of Irritable Bowel Syndrome (IBS):
- IBS is an idiopathic, chronic, relapsing disorder characterized by abdominal discomfort and alterations in bowel habits (diarrhea, constipation, or both).
- Pharmacotherapies for IBS focus on relieving abdominal pain and improving bowel function.
- Antidiarrheals (e.g., loperamide) are helpful for patients with predominant diarrhea.
- Fiber supplements may soften stools and reduce straining in constipation-predominant IBS.
- Low doses of tricyclic antidepressants (e.g., amitriptyline, desipramine) may be helpful for chronic abdominal pain.
- Other agents, including anticholinergics, 5-HT3 & 5-HT4 receptor antagonists, may be used.

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Description

Test your knowledge on gastrointestinal motility disorders, focusing on the pharmacotherapy of nausea and vomiting. Understand the physiological processes involved in vomiting and related conditions. This quiz will assess your comprehension of the interaction between the gastrointestinal tract and nervous system.