Antiemetics and Nausea Management

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Questions and Answers

Which of the following is a primary use for certain antiemetics, other than preventing nausea and vomiting caused by chemotherapy?

As a prokinetic agent. (correct)

Reducing tachycardia.

Treating arrhythmias.

Dilating pupils.

A patient who is on an antiemetic and also has a pre-existing condition of congestive heart failure should avoid treatment with which of the following medications?

Olanzapine

Amisulpride (correct)

Nabilone

Scopolamine

What is a key mechanism of action for the antiemetic drug class of Cannabinoids?

Stimulating cannabinoid CB1 receptors in the brainstem DVC and GIT. (correct)

Acting as a D2 antagonist in the brainstem.

Blocking muscarinic receptors in the DVC.

Blocking dopamine D1,2,3,4 receptors.

Which of the following side effects is NOT commonly associated with antimuscarinic medications?

Hypotension Signup and view all the answers

What is a significant metabolic characteristic of Olanzapine?

More than 40% is removed by hepatic first-pass effect. Signup and view all the answers

Which of the following is a primary use for histamine H1 receptor antagonists?

Motion sickness Signup and view all the answers

The mechanism of action of dopamine D2 receptor antagonists involves the DVC's:

Blocking of dopamine D2 receptors Signup and view all the answers

Which of the following side effects is most likely to occur when taking promethazine?

Drowsiness Signup and view all the answers

Which of the following drugs has been associated with fatal cardiac arrythmias?

Droperidol Signup and view all the answers

What condition is haloperidol used to treat?

Cannabinoid hyperemesis syndrome Signup and view all the answers

A patient experiences restlessness and an inability to sit still after being administered an antiemetic. Which of the following adverse effects is most likely causing this?

Akathisia Signup and view all the answers

A patient is experiencing vomiting due to a viral gastroenteritis. Which of the following medications is least appropriate for this condition?

Dimenhydrinate Signup and view all the answers

Which of the following medications blocks both serotonin 5-HT3 and dopamine D2 receptors?

Metoclopramide Signup and view all the answers

Which of the following best describes the primary mechanism of first-generation 5-HT3 receptor antagonists in managing chemotherapy-induced nausea and vomiting (CINV)?

They primarily attenuate the immediate phase of CINV by blocking serotonin receptors. Signup and view all the answers

What is the particular advantage of palonosetron over first-generation 5-HT3 receptor antagonists in managing CINV?

Palonosetron more potently attenuates both phases of CINV due to its higher affinity and additional effects, including receptor internalization. Signup and view all the answers

What is the rationale for using larger doses of 5-HT3 receptor antagonists intravenously, as indicated in the text?

To combat emesis induced by highly emetogenic cancer chemotherapeutics, where oral doses might not be sufficient. Signup and view all the answers

What does the term 'triple prophylactic therapy' refer to regarding CINV management?

The combined use of a 5-HT3 receptor antagonist, dexamethasone, and an NK1 receptor antagonist. Signup and view all the answers

How does the drug netupitant contribute to the management of CINV when combined with palonosetron?

Netupitant is a second-generation NK1 receptor antagonist that works in combination with palonosetron for prophylactic CINV antiemetic therapy. Signup and view all the answers

Which of the following is a common adverse effect of 5-HT3 receptor antagonists?

Headache Signup and view all the answers

Which of these 5-HT3 receptor antagonists has the longest half-life?

Palonosetron Signup and view all the answers

Which enzyme primarily metabolizes granisetron?

CYP1A1 Signup and view all the answers

Which of the following mechanisms is associated with the action of NK1 receptor antagonists, in relation to Substance P?

Prevent Substance P from exciting its receptors. Signup and view all the answers

Which of the following is a symptom of serotonin syndrome?

Muscle rigidity Signup and view all the answers

Which class of antiemetic is most effective against the delayed phase of chemotherapy-induced nausea and vomiting (CINV)?

NK1 receptor antagonists Signup and view all the answers

What is a potential consequence of combining 5-HT3 receptor antagonists with selective serotonin reuptake inhibitors?

Serotonin syndrome Signup and view all the answers

Which of these statements is TRUE for 5-HT3 receptor antagonists?

They exhibit moderate plasma protein binding. Signup and view all the answers

Which of the following is NOT a primary location of emetic loci in the brainstem?

Cerebral cortex Signup and view all the answers

What is the primary neurotransmitter found within enterochromaffin (EC) cells of the gastrointestinal tract, that plays a role in the emetic response?

Serotonin (5-HT) Signup and view all the answers

Which of these mechanisms is MOST directly involved in relaying emetic stimuli from the brainstem to the gastrointestinal tract (GIT)?

Dorsal motor nucleus of the vagus (DMNX) Signup and view all the answers

Which receptor type, found in the area postrema (AP), is associated with the binding of serotonin, an important emetic neurotransmitter?

5-HT3 Signup and view all the answers

Which of the following is a feature of the Central Pattern Generator (CPG)?

Directly involved in the motor pattern of emesis Signup and view all the answers

What is the effect of emetogens on the central/peripheral emetic loci?

Activate central and/or peripheral emetic loci Signup and view all the answers

Which of the following is NOT a recognized cause of the release of emetic neurotransmitters?

Pain Signup and view all the answers

Where are the receptors involved in mediating nausea mainly located?

Higher brain centers such as cerebral cortex Signup and view all the answers

Which of the following factors influence the choice of antiemetic medication?

Underlying cause of nausea/vomiting Signup and view all the answers

What distinguishes the action of most antiemetics?

They are primarily antagonists at emetic receptors Signup and view all the answers

According to the information provided, which of the following is NOT typically associated with NK1 receptor antagonists?

Elevated Blood Pressure Signup and view all the answers

What is the primary neurotransmitter released in the gut tissue during the early phase of chemotherapy-induced nausea and vomiting (CINV), according to traditional understanding?

Serotonin Signup and view all the answers

According to traditional understanding, what is the primary neurotransmitter released in the brainstem during the delayed phase of CINV?

Substance P Signup and view all the answers

According to more recent findings, what is the nature of neurotransmitter release during both the early and delayed phases of CINV?

Concomitant release of several neurotransmitters including serotonin, substance P, and dopamine. Signup and view all the answers

Metoclopramide is described as having which of the following pharmacological actions?

Dopamine D2 receptor and 5-HT3 receptor antagonist Signup and view all the answers

Which of the following is a known effect of the antiemetic olanzapine?

Reduces nausea and vomiting caused by chemotherapeutics. Signup and view all the answers

What is a potential cause of infusion site reactions following intravenous administration of NK1 receptor antagonists?

Formulation ingredients of the drug itself Signup and view all the answers

According to the content, which of the following is a common side effect of NK1 receptor antagonists?

Constipation Signup and view all the answers

Study Notes

Antiemetics

Antiemetics are drugs used to treat nausea and vomiting.
Not all antiemetics work for all types of vomiting.
Some antiemetics are agonists, while most are antagonists.

Objectives

Discuss neuroanatomy of vomiting.
Discuss the neuroanatomy and receptor mechanisms of emetic neurotransmitters.
Determine if currently used antiemetics reduce nausea.
Understand pharmacology and mechanisms of antiemetic actions, and clinical uses of emetrol, anti-muscarinics, anti-histamines, dopamine D₂ antagonists, metoclopramide, cannabinoids, and olanzapine.
Discuss pharmacology and clinical application of first- and second-generation serotonin 5-HT₃ receptor antagonist antiemetics.
Discuss pharmacology and clinical application of substance P neurokinin NK₁ receptor antagonist antiemetics.
Describe acute and delayed phases of chemotherapy-induced nausea and vomiting and prophylactic antiemetic therapy.

Nausea and Vomiting (Emesis)

Nausea is an unpleasant feeling of imminent vomiting.
Its neurochemistry and neuroanatomy are not well understood.
Emesis is the act of forcefully removing gastrointestinal content.
Both nausea and emesis are protective mechanisms.
Nausea and vomiting can have a variety of causes, conditions, or drugs.

Emesis

Emetic reflex is a highly complex system.
Chemotherapy-induced nausea and vomiting (CINV), radiation, infections, and pregnancy can cause emesis.
Emetic neurotransmitters may include serotonin, dopamine, substance P, prostaglandins, and leukotrienes.

Central & Peripheral Emetic Neurotransmitters & Corresponding Receptors

Dorsal Vagus Complex (DVC) in the brainstem contains the area postrema (AP), nucleus tractus solitarius (NTS), dorsal motor nucleus of the vagus (DMNX), and central pattern generator (CPG).
Gastrointestinal tract (GIT), enterochromaffin cells, vagal afferents/efferents, splanchnic nerves, and vestibular apparatus in the inner ear have peripheral emetic loci.

Antiemetics Overview

No one antiemetic is effective for all types of vomiting.
Choices are based on the reason, location and cause.

Antiemetics- Specific Drugs

Emetrol: Oral suspension of fructose, glucose, and phosphate used for motion sickness, pregnancy-induced vomiting, or drug-induced vomiting
Histamine H₁ Receptor Antagonists: Block emetic vestibular afferent activity from the inner ear, used for motion sickness, and vertigo. (Examples are Dimenhydrinate, Diphenhydramine, Cyclizine & Meclizine)
Dopamine D₂ Receptor Antagonists I: Block dopamine D₂ receptors in the CTZ. (Examples are Phenothiazines and butyrophenones)
Dopamine D₂ Receptor Antagonists II: Block serotonin 5-HT₃ and dopamine D₂ receptors. (Examples are Metoclopramide, Amisulpride, Olanzapine)
Glucocorticoids: Anti-inflammatory agents like dexamethasone used to treat radiotherapy- or chemotherapy-induced nausea and vomiting (CINV), and other conditions.
Serotonin 5-HT₃ Receptor Antagonists I: Block 5-HT₃ receptors. (Examples are Ondansetron, Granisetron, Dolasetron & Palonosetron)
Serotonin 5-HT₃ Receptor Antagonists II: Attenuates immediate-phase of CINV.
Neurokinin NK₁ Receptor Antagonists I & II: Block NK₁ receptors. (Examples are Aprepitant, Netupitant and Rolapitant)
Neurokinin NK₁ Receptor Antagonists III: Undergo hepatic metabolism by CYP3A4
Neurokinin NK₁ Receptor Antagonists IV: Potential exists for drug-drug interactions

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Description

This quiz focuses on the pharmacology and mechanisms of antiemetics used to treat nausea and vomiting. It covers various antiemetics, their receptor mechanisms, and their clinical applications. Additionally, it addresses the neuroanatomy behind vomiting and the phases of chemotherapy-induced nausea.