Podcast
Questions and Answers
Which class of drugs acts primarily on D2 receptors in the chemoreceptor trigger zone (CTZ)?
Which class of drugs acts primarily on D2 receptors in the chemoreceptor trigger zone (CTZ)?
What is the primary site of action for glucocorticoids in the treatment of nausea and vomiting?
What is the primary site of action for glucocorticoids in the treatment of nausea and vomiting?
Which type of drug is known to cause sedation and has anticholinergic actions in the vestibular apparatus?
Which type of drug is known to cause sedation and has anticholinergic actions in the vestibular apparatus?
Which class of drugs is often used in combination with other medications to enhance effectiveness in treating cytotoxic drug-induced vomiting (CINV)?
Which class of drugs is often used in combination with other medications to enhance effectiveness in treating cytotoxic drug-induced vomiting (CINV)?
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Which of the following drugs is NOT classified as an antimuscarinic?
Which of the following drugs is NOT classified as an antimuscarinic?
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What type of antagonists are ondansetron and granisetron classified as?
What type of antagonists are ondansetron and granisetron classified as?
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What triggers the reflex mechanism to remove irritating or toxic material?
What triggers the reflex mechanism to remove irritating or toxic material?
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Which neurotransmitter is NOT mentioned as being involved in the vomiting reflex?
Which neurotransmitter is NOT mentioned as being involved in the vomiting reflex?
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The chemoreceptor trigger zone (CTZ) is sensitive to which of the following?
The chemoreceptor trigger zone (CTZ) is sensitive to which of the following?
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Which of these statements is true regarding cardiac rhythm disturbances during vomiting?
Which of these statements is true regarding cardiac rhythm disturbances during vomiting?
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What is the main role of vagal afferent fibers in the vomiting process?
What is the main role of vagal afferent fibers in the vomiting process?
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What is a potential effect of the proximity of the medullary vomiting and salivary centers?
What is a potential effect of the proximity of the medullary vomiting and salivary centers?
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Which factor is NOT directly linked to the control of vomiting?
Which factor is NOT directly linked to the control of vomiting?
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What characteristic describes the location of the chemoreceptor trigger zone (CTZ)?
What characteristic describes the location of the chemoreceptor trigger zone (CTZ)?
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Which neurotransmitter is associated with vagal afferents in the vomiting mechanism?
Which neurotransmitter is associated with vagal afferents in the vomiting mechanism?
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During which scenario might defecation accompany vomiting?
During which scenario might defecation accompany vomiting?
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Which region of the central nervous system is primarily involved in coordinating nausea and vomiting?
Which region of the central nervous system is primarily involved in coordinating nausea and vomiting?
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Which of the following is a common trigger for nausea and vomiting?
Which of the following is a common trigger for nausea and vomiting?
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What consequence can result from severe vomiting?
What consequence can result from severe vomiting?
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Which of the following descriptions best defines nausea?
Which of the following descriptions best defines nausea?
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What is the primary focus of pharmacological treatment for nausea and vomiting?
What is the primary focus of pharmacological treatment for nausea and vomiting?
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Which of these conditions is NOT commonly associated with nausea and vomiting?
Which of these conditions is NOT commonly associated with nausea and vomiting?
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What role do visceral pain and unpleasant memories play in the experience of nausea?
What role do visceral pain and unpleasant memories play in the experience of nausea?
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Which one of the following is NOT a cause of drug-induced nausea and vomiting?
Which one of the following is NOT a cause of drug-induced nausea and vomiting?
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What happens to gastric motility during nausea?
What happens to gastric motility during nausea?
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What role does the cerebellum play in the connection between the labyrinth and the chemoreceptor trigger zone (CTZ)?
What role does the cerebellum play in the connection between the labyrinth and the chemoreceptor trigger zone (CTZ)?
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Which of the following is a muscarinic type 1 receptor antagonist used as an antiemetic?
Which of the following is a muscarinic type 1 receptor antagonist used as an antiemetic?
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What type of receptor antagonism does ondansetron primarily target?
What type of receptor antagonism does ondansetron primarily target?
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Which drug class is primarily effective for motion sickness?
Which drug class is primarily effective for motion sickness?
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Which of the following antiemetics is classified as a D2 receptor antagonist?
Which of the following antiemetics is classified as a D2 receptor antagonist?
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What side effect is most commonly associated with phenothiazines?
What side effect is most commonly associated with phenothiazines?
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Where are NK1 receptors primarily located?
Where are NK1 receptors primarily located?
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Which medication contains emetine and is commonly used for inducing vomiting?
Which medication contains emetine and is commonly used for inducing vomiting?
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Which of the following drugs is a 5-HT3 antagonist?
Which of the following drugs is a 5-HT3 antagonist?
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Which of these medications has anti-muscarinic activity alongside being an H1 receptor antagonist?
Which of these medications has anti-muscarinic activity alongside being an H1 receptor antagonist?
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How do dopamine (D2-receptor) antagonists primarily function?
How do dopamine (D2-receptor) antagonists primarily function?
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What is a significant side effect of THC-related drugs like nabilone?
What is a significant side effect of THC-related drugs like nabilone?
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What is the primary purpose of administering antiemetics like promethazine?
What is the primary purpose of administering antiemetics like promethazine?
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Which compounds are known agonists at NK1 receptors?
Which compounds are known agonists at NK1 receptors?
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Which drug would be commonly used for delayed phase nausea in chemotherapeutic-induced nausea and vomiting?
Which drug would be commonly used for delayed phase nausea in chemotherapeutic-induced nausea and vomiting?
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What is a common use for activated charcoal in conjunction with antiemetics?
What is a common use for activated charcoal in conjunction with antiemetics?
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Which group of medications can be administered rectally and is useful when vomiting has already started?
Which group of medications can be administered rectally and is useful when vomiting has already started?
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What common gastrointestinal side effect is associated with 5-HT3 antagonists?
What common gastrointestinal side effect is associated with 5-HT3 antagonists?
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What is the mechanism of action for NK1 antagonists such as aprepitant?
What is the mechanism of action for NK1 antagonists such as aprepitant?
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What is a common indication for using corticosteroids in the context of nausea and vomiting management?
What is a common indication for using corticosteroids in the context of nausea and vomiting management?
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Study Notes
Applied Pharmacology of the Nervous & Endocrine Systems
- Focuses on nausea and vomiting (N&V) pharmacology
- Targets Year 2 Pharmacy students (M33522)
- Part of a larger course (M33319)
- Based on Rang & Dale's Pharmacology (Chapter 30)
- Covers medical pharmacology in general
Learning Objectives
- Detail the CNS region coordinating N&V
- Explain N&V triggers (motion sickness, drug-induced, chemotherapy-induced)
- Outline the mechanism of action for antiemetic drugs
- Identify and recommend suitable pharmacological treatments for N&V
Nausea & Vomiting
- Unwanted side effects of various medications (e.g., cancer chemotherapy, opioids, general anesthetics, digoxin, SSRIs)
- May indicate underlying diseases/disorders like motion sickness, bacterial/viral infections, and others
- Can lead to significant complications like aspiration pneumonia, Mallory-Weiss syndrome, esophageal rupture, dehydration, electrolyte depletion, acid-base imbalances, and malnutrition
Diseases and Conditions
- Drug toxicity, pregnancy, motion sickness, gastrointestinal obstructions, hepatitis, pancreatitis, myocardial infarction, renal failure, increased intracranial pressure, asthma, Zollinger-Ellison syndrome, diabetes mellitus, thyrotoxicosis, and epilepsy, are important factors
Vomiting: Importance
- Aspiration pneumonia, Mallory-Weiss tears, esophageal rupture (Boerhaave's syndrome), volume/electrolyte depletion, acid-base imbalances, and malnutrition are potential life-threatening consequences
Components of Vomiting
- Nausea: unpleasant feeling, potentially preceding vomiting
- Stimuli: labyrinth stimulation, visceral pain, unpleasant memories, and various drugs can cause nausea. Mild pathway activation leads to nausea. Severe activation leads to retching or vomiting.
Location of Vomiting Centre and CTZ
- The vomiting center and chemoreceptor trigger zone (CTZ) are located in the brainstem (specifically the medulla oblongata)
Nausea and Intestinal Motility
- Gastric tone and peristalsis are reduced during nausea.
- Duodenal and proximal jejunum tone tends to be increased.
- Reflux of duodenal contents into the stomach is common during nausea.
The Reflex Mechanism
- Vomiting is a defensive response to remove irritants/toxins.
- Triggered by factors like poisons, bacterial toxins, and cytotoxic drugs.
- Enterochromaffin cells release 5-HT, which activates vagal afferent fibers.
- The vomiting/emetic center in the medulla coordinates this response.
- Chemoreceptor trigger zone (CTZ) also sends input to the medulla
- CTZ receives input from vestibular nuclei (motion), vagal afferents (GI tract), and higher cortical centers (emotional) as well as the blood (circulating drugs/toxins).
Main Neurotransmitters Involved
- Acetylcholine (M₁)
- Histamine (H₁)
- 5-hydroxytryptamine (5-HT3)
- Dopamine (D2)
- Substance P (neurokinin receptors)
Location of Other Centres in the Medulla
- Hypersalivation: close proximity of medullary vomiting and salivary centers.
- Cardiac Rhythm Disturbances: Nausea often accompanies tachycardia (rapid heartbeat) while retching can be accompanied by bradycardia (slow heartbeat). Cardiac arrhythmias may occur with retching and vomiting.
- Defecation: vomiting and defecation pathways are adjacent, potentially triggered by the same stimuli.
Anatomy (CTZ) Continued
- The chemoreceptor trigger zone (CTZ) lies outside the blood-brain barrier in the area postrema.
- It's sensitive to various substances such as apomorphine, morphine, general anesthetics, cardiac glycosides, certain chemotherapeutic agents, and maternal hormones (e.g., hCG).
- Key receptors in the CTZ include dopamine (D2) and 5-HT3 receptors
Chemical Structures of Antiemetics
- Shows chemical structures of various antiemetic drugs (acetylcholine, scopolamine, histamine, cinnarizine, promethazine, dopamine, 5-hydroxytryptamine, metoclopramide, ondansetron, and others).
- Illustrations of the molecular structures
Antiemetics (Continued)
- Phenothiazines (ACh and H₁ antagonists)
- Dopamine (D₂) antagonists
- 5-HT₃ antagonists
- NK₁ antagonists
- THC (Tetrahydrocannabinol)
- Corticosteroids
Summary of Action of Common Antiemetics
- Listing of different classes of antiemetics (antihistamines, anticholinergics, cannabinoids, dopamine antagonists, glucocorticoids, 5-HT3 antagonists, neurokinin-1 antagonists), their corresponding sites of action and key side effects and clinical uses.
Vomiting During Pregnancy
- Dietary and lifestyle changes are often helpful alongside other treatments
- Treatment focus is on mild pregnancy sickness cases, rather than severe ones
Hyperemesis Gravidarum
- A severe form of morning sickness
- Symptoms include persistent nausea and vomiting, malnutrition, weight loss, electrolyte disturbance, and potentially life-threatening complications.
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Description
Test your knowledge on the pharmacological aspects of nausea and vomiting, focusing on drug classes and their mechanisms of action. This quiz covers various drug interactions, receptors, and neurotransmitters relevant to the treatment of nausea and vomiting.
