Lesson 20: Vomiting Pathophysiology
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Questions and Answers

Which neurotransmitter is NOT primarily involved in the vomiting pathway as described?

  • Serotonin
  • Acetylcholine
  • Adrenaline (correct)
  • Histamine
  • What is the primary action of H1 receptor antagonists in relation to vomiting?

  • They block both H1 and M receptors in vestibular nuclei. (correct)
  • They inhibit dopamine pathways.
  • They stimulate the gastrointestinal tract.
  • They enhance the release of serotonin.
  • Which type of receptors are implicated in the effects of motion sickness?

  • 5-HT3 receptors
  • NMDA receptors
  • M receptors (correct)
  • D2 receptors
  • Which condition is least likely to cause vomiting as described?

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

    Which of the following drugs would likely be classified as a 5-HT3 receptor antagonist?

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

    What adverse effect is most commonly associated with first-generation antihistamines?

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

    Which of the following actions is true regarding enkephalins in the context of vomiting?

    <p>Their involvement is hypothesized. (C)</p> Signup and view all the answers

    Which of the following stimuli is most likely to trigger nausea in patients?

    <p>Viewing unpleasant images (D)</p> Signup and view all the answers

    What is the first line treatment for nausea and vomiting in pregnancy?

    <p>Pyridoxine 10-25 mg every 8 hours (D)</p> Signup and view all the answers

    Which medication is used as a second-line treatment for nausea and vomiting when anti-H1 options fail?

    <p>Dimenhydrinate 50-100 mg orally (D)</p> Signup and view all the answers

    Which of the following is NOT a common symptom of Ménière's disease?

    <p>Nasal congestion (C)</p> Signup and view all the answers

    Which medication is characterized as an H3 receptor antagonist and a partial H1 agonist for the prevention of Ménière's attacks?

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

    What is the role of dexamethasone in treating Ménière's disease?

    <p>Serves as an immune modulator for potential autoimmune cases (C)</p> Signup and view all the answers

    Which antipsychotic medication also serves for severe nausea and vomiting as indicated in treatments for Ménière's disease?

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

    What are the potential adverse effects of scopolamine, particularly in the context of motion sickness treatment?

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

    If symptoms of nausea do not resolve with first-line treatments, which of the following should be considered?

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

    What is the primary mechanism of action for 5-HT3 receptor antagonists in reducing nausea and vomiting?

    <p>Blocking 5-HT3 receptors in the gastrointestinal tract (B)</p> Signup and view all the answers

    In which situation is ondansetron typically indicated for use?

    <p>Highly emetogenic chemotherapy (C)</p> Signup and view all the answers

    What adverse effect is notably associated with metoclopramide due to its D2 antagonist properties?

    <p>Galactorrhea and menstrual disorders (B)</p> Signup and view all the answers

    What distinguishes domperidone from other dopamine antagonists in its clinical use?

    <p>It does not penetrate the blood-brain barrier (B)</p> Signup and view all the answers

    For which condition are antipsychotic drugs primarily used as antiemetics?

    <p>Severe nausea and vomiting associated with cancer treatments (B)</p> Signup and view all the answers

    Which of the following statements is true regarding NK1 receptor antagonists?

    <p>They block substance P receptors in the CTZ and vomiting center. (B)</p> Signup and view all the answers

    What serious risk is associated with the use of domperidone, particularly at higher doses?

    <p>Serious cardiac adverse effects (A)</p> Signup and view all the answers

    Which of the following is a common side effect of chlorpromazine used as an antiemetic?

    <p>Sedation and hypotension (D)</p> Signup and view all the answers

    What is the primary mechanism of action of dopamine antagonists like metoclopramide?

    <p>D2 receptor antagonism in the CNS (A)</p> Signup and view all the answers

    Which condition is specifically treated with domperidone due to its unique properties?

    <p>Levodopa-induced vomiting in Parkinson's disease (C)</p> Signup and view all the answers

    What adverse effect is associated with the use of first-generation antipsychotics for antiemetic purposes?

    <p>Extrapyramidal symptoms (D)</p> Signup and view all the answers

    What is a significant side effect associated with the use of NK1 receptor antagonists?

    <p>Cardiac adverse effects at high doses (C)</p> Signup and view all the answers

    Which receptor is primarily targeted by 5-HT3 receptor antagonists to mitigate nausea and vomiting?

    <p>5-HT3 receptor (A)</p> Signup and view all the answers

    What is the preferred method of administration for dopamine antagonists when treating severe nausea and vomiting?

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

    What general class of drugs does palonosetron belong to for managing nausea and vomiting?

    <p>5-HT3 receptor antagonists (A)</p> Signup and view all the answers

    What is a notable central nervous system side effect of metoclopramide?

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

    What role do afferent pathways play in the vomiting process?

    <p>They transmit signals from the GI tract to initiate vomiting. (B)</p> Signup and view all the answers

    Which of the following neurotransmitters is NOT primarily associated with the vomiting pathway?

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

    What is a common adverse reaction of first-generation antihistamines used as antiemetics?

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

    Which condition is most likely to be treated with 5-HT3 receptor antagonists?

    <p>Chemotherapy-induced nausea (D)</p> Signup and view all the answers

    What is the primary function of NK1 receptor antagonists in antiemetic treatment?

    <p>To inhibit the action of substance P. (D)</p> Signup and view all the answers

    Which receptor types are primarily targeted by antiemetic medications for treating motion sickness?

    <p>Histamine and muscarinic receptors (D)</p> Signup and view all the answers

    What is the hypothesized role of enkephalins in the context of vomiting?

    <p>They act as inhibitors to mitigate the vomiting reflex. (B)</p> Signup and view all the answers

    What is the main mechanism of action for antihistamines in treating nausea and vomiting?

    <p>Antagonism of histamine receptors in the vestibular system. (D)</p> Signup and view all the answers

    What is the recommended dosage range for pyridoxine as a first-line treatment for nausea and vomiting during pregnancy?

    <p>10-25 mg every 8 hours (D)</p> Signup and view all the answers

    Which of the following medications is used for acute attacks in Ménière's disease?

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

    Which medication can be considered for unresolved nausea and vomiting after trying anti-H1 options?

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

    What characteristic of betahistine makes it effective for preventing Ménière's attacks?

    <p>It is a H3 receptor antagonist and a partial H1 agonist (C)</p> Signup and view all the answers

    What is a potential adverse effect of using scopolamine for motion sickness?

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

    Which route of administration is likely to have fewer adverse effects for scopolamine?

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

    What distinguishes prochlorperazine as a treatment in the context of severe nausea?

    <p>It is also categorized as an antipsychotic medication (B)</p> Signup and view all the answers

    Flashcards

    Vomiting: Pathophysiology

    A complex signaling cascade involving various brain regions and neurotransmitters that ultimately leads to the expulsion of stomach contents.

    Vomit Center

    The medulla oblongata, specifically the 'vomit center', is responsible for coordinating the complex muscle contractions involved in vomiting.

    Chemoreceptor Trigger Zone (CTZ)

    The chemoreceptor trigger zone (CTZ) is a sensitive area in the brain that detects toxins, drugs, and other substances that can trigger vomiting.

    Neurotransmitters Involved in Vomiting

    Neurotransmitters like acetylcholine, histamine, serotonin, dopamine, and substance P play crucial roles in the vomiting process. They transmit signals between different brain regions involved in the vomiting reflex.

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    Antiemetic Drugs: Mechanism

    Drugs that block the actions of specific neurotransmitters involved in vomiting can help alleviate nausea and vomiting. They are categorized by the specific neurotransmitter they target.

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    H1 Receptor Antagonists

    H1 receptor antagonists like promethazine, dimenhydrinate, and betahistine work by blocking histamine receptors in the vestibular nuclei and the gastrointestinal tract.

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    Motion Sickness and H1 Antagonists

    Motion sickness is often treated with antihistamines that block H1 receptors in the vestibular nuclei, which plays a crucial role in balance and movement.

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    Antihistamines: Side effects

    Drowsiness and sedation are common side effects of some antihistamines, especially older generations of drugs.

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    Antihistamines (H1 Receptor Antagonists)

    A type of medication that blocks the effects of histamine at H1 receptors. They are used to treat nausea and vomiting in pregnancy.

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    Pyridoxine (Vitamin B6)

    Vitamin B6, a first-line treatment for nausea and vomiting in pregnancy. It is often combined with other antihistamines like doxylamine.

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    Metoclopramide (D Antagonist)

    A type of medication that blocks the effects of dopamine (D) receptors. It is used as an option if other antiemetics fail.

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    Ondansetron (5-HT3 Antagonist)

    A type of medication that blocks the effects of serotonin at 5-HT3 receptors. It is another option for treating nausea and vomiting if other medications are unsuccessful.

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    Prochlorperazine

    A powerful antiemetic, commonly known as an antipsychotic, used to treat severe nausea and vomiting. It is typically given buccally or intramuscularly.

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    Dexamethasone

    An immune modulator used intratympanically to treat vertigo in Meniere's disease. Its action suggests an autoimmune role in the disease.

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    Scopolamine (Hyoscine)

    A drug that blocks muscarinic receptors, used to prevent and treat motion sickness. Oral or intramuscular administration is reserved for short or intense motion exposure.

    Signup and view all the flashcards

    Betahistine

    A medication that acts as a partial H1 agonist and an H3 antagonist. It is prescribed for preventing attacks of Meniere's disease.

    Signup and view all the flashcards

    5-HT3 Receptor Antagonists

    These drugs block 5-HT3 receptors in the gastrointestinal tract and the chemoreceptor trigger zone (CTZ), preventing the activation of pathways that lead to nausea and vomiting.

    Signup and view all the flashcards

    Metoclopramide (Dopamine Antagonist)

    Metoclopramide is a dopamine antagonist used for vomiting related to migraines, gastroesophageal reflux, and liver/gallbladder disorders.

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    Domperidone (Dopamine Antagonist)

    Domperidone is a dopamine antagonist that doesn't reach the brain, making it safer for vomiting related to levodopa (Parkinson's) and cytotoxic treatments.

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    Antiemetic Antipsychotics

    These antipsychotics (like chlorpromazine, prochlorperazine, and perphenazine) are effective antiemetics for severe nausea and vomiting from various causes, including chemotherapy, radiation therapy, and opioid use.

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    Haloperidol and Droperidol (Dopamine Antagonists)

    These drugs (like haloperidol and droperidol) are used for acute chemotherapy-induced vomiting but have limited use due to potential side effects.

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    Examples of 5-HT3 Receptor Antagonists

    Granisetron, Ondansetron, and Palonosetron are medications that belong to the class of 5-HT3 receptor antagonists.

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    Common Indications for Antiemetics

    Chemotherapy-induced nausea and vomiting, postoperative nausea and vomiting.

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    What is the pathophysiology of vomiting?

    Vomiting is a complex process involving the brain, GI tract, and specific neurotransmitters. When triggered, it results in the expulsion of stomach contents through coordinated muscle contractions.

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    What is the Chemoreceptor Trigger Zone (CTZ)?

    The Chemoreceptor Trigger Zone (CTZ) is a specialized area in the brain that is highly sensitive to toxins, drugs, and other harmful substances. When activated, it sends signals to the vomit center, triggering the vomiting reflex.

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    What are some neurotransmitters involved in the vomiting process?

    Neurotransmitters like acetylcholine, histamine, serotonin, dopamine, and substance P play key roles in vomiting by transmitting signals between different brain regions involved in the vomiting reflex.

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    What are antiemetic drugs?

    Antiemetic drugs are medications designed to prevent or reduce nausea and vomiting. Different types of antiemetics work by targeting specific neurotransmitters involved in the vomiting process.

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    How do H1 receptor antagonists work?

    H1 receptor antagonists like promethazine or dimenhydrinate block histamine receptors in the vestibular nuclei and the GI tract, reducing motion sickness and nausea from stomach irritants.

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    What is the mechanism of action for 5-HT3 receptor antagonists?

    5-HT3 receptor antagonists like ondansetron block serotonin receptors in the GI tract and the CTZ, preventing the activation of pathways leading to nausea and vomiting.

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    How do dopamine antagonists work?

    Dopamine antagonists like metoclopramide block dopamine receptors, playing a role in reducing nausea and vomiting connected to migraines, gastroesophageal reflux, and liver/gallbladder issues.

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    What are antiemetic antipsychotics used for?

    Antiemetic antipsychotics, such as prochlorperazine, are used to treat severe nausea and vomiting from causes like chemotherapy, radiation therapy, and opioid use, by targeting dopamine receptors.

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    What is the first-line treatment for nausea and vomiting in pregnancy?

    Vitamin B6, also known as pyridoxine, is the first-line treatment for nausea and vomiting in pregnancy. It's often used in combination with other antihistamines like doxylamine.

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    What are H1 receptor antagonists?

    H1 receptor antagonists are a class of medications that block the effects of histamine at H1 receptors, helping to alleviate nausea and vomiting.

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    Give examples of medications that are H1 receptor antagonists

    Promethazine, dimenhydrinate, and betahistine are examples of H1 receptor antagonists used to treat nausea and vomiting.

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    What antihistamine is often used with pyridoxine during pregnancy?

    Doxylamine is an H1 receptor antagonist often used in combination with pyridoxine (vitamin B6) for the treatment of nausea and vomiting in pregnancy.

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    What medication is known as an antipsychotic but is also used as a potent antiemetic?

    Prochlorperazine is a powerful antiemetic, often classified as an antipsychotic, used to treat severe nausea and vomiting. It's typically administered buccally or intramuscularly.

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    What medication is used to prevent and treat motion sickness by blocking muscarinic receptors?

    Scopolamine (hyoscine) is a medication that blocks muscarinic receptors, used to prevent and treat motion sickness. Oral or intramuscular administration is typically reserved for short, intense motion exposure or individuals highly susceptible to motion sickness.

    Signup and view all the flashcards

    What medication, with both H1 and H3 receptor actions, is used to prevent Meniere's disease attacks?

    Betahistine is a medication that acts as a partial H1 agonist and an H3 antagonist. It's prescribed for preventing attacks of Meniere's disease.

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    Which medication, used intratympanically, is considered an immune modulator and helps treat vertigo in Meniere's disease?

    Dexamethasone is an immune modulator used intratympanically to treat vertigo in Meniere's disease. It suggests an autoimmune role in the disease.

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    5-HT3 Receptor Antagonists: How do they work?

    5-HT3 receptor antagonists block serotonin receptors in the GI tract and CTZ, preventing signals that cause nausea and vomiting.

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    Name 3 examples of 5-HT3 Receptor Antagonists.

    Granisetron, Ondansetron, and Palonosetron are commonly used 5-HT3 antagonists.

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    How does Metoclopramide work?

    Metoclopramide works by blocking dopamine receptors in the CTZ (central) and stimulating gut motility (peripheral).

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    What are some side effects of Metoclopramide?

    Although effective, Metoclopramide can cause dyskinesia (involuntary movements) and stimulate prolactin, leading to menstrual issues.

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    How does Domperidone differ from Metoclopramide?

    Domperidone is a dopamine antagonist that doesn't cross the blood-brain barrier, meaning it's safer for nausea caused by Parkinson's medication.

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    What are some common antipsychotics used as antiemetics?

    Dopamine antagonists like Chlorpromazine, Prochlorperazine, and Perphenazine are powerful antiemetics for severe nausea.

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    What are Haloperidol and Droperidol used for, and why is their use limited?

    Haloperidol and Droperidol are dopamine antagonists used for acute nausea from chemotherapy, but their use is limited due to side effects.

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    What is the mechanism of action of NK1 receptor antagonists?

    NK1 receptor antagonists work by blocking substance P receptors in the CTZ and vomiting center, thus inhibiting nausea.

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    Study Notes

    Lesson 20: Vomiting

    • This lesson covers vomiting, its pathophysiology, and antiemetic drugs.
    • The academic year is 2024/25.
    • The professor is Vittoria Carrabs PhD.

    1. Pathophysiology of Vomiting

    • Vomiting is a complex process involving multiple steps.
    • Stimuli initiate the process, which travels through sensory pathways to the medulla.
    • The medulla contains the vomit center, integrating signals and coordinating emesis.
    • The vomit center then stimulates the gastrointestinal tract and diaphragm, resulting in vomiting.
    • Factors involved include unpleasant images/odors/emotions, irritative stimuli (chemo, radiotherapy, gastroenteritis); motion sickness, vertigo, toxins, drugs.
    • The labyrinth, vestibular nuclei, and chemoreceptor trigger zone (CTZ) play vital roles in this process, with the CTZ receiving input from the blood regarding emetogens and integrating stimuli.
    • Neurotransmitters involved include acetylcholine, histamine, dopamine, substance P, and Enkephalins.

    2. Antiemetic Drugs

    • These are drugs used to treat nausea and vomiting.

    2.1 Antihistamines (H1 receptor antagonists)

    • These drugs effectively treat nausea and vomiting arising from various causes, including motion sickness and stomach irritants.
    • Examples include promethazine, dimenhydrinate, betahistine, and doxylamine.
    • The mechanism of action involves blocking H1 receptors in the vestibular nuclei and gastrointestinal tract.
    • Side effects can include drowsiness and sedation.
    • Specific examples include Biodramina 50mg (Dimenhydrinate), Promethazine, Doxylamine (12.5-25 mg every 8 hours). Pyridoxine (vitamin B6) 10-25 mg every 8 hours is a first-line treatment for nausea and vomiting in pregnancy.

    2.2 Muscarinic Receptor Antagonists

    • Scopolamine (Hyoscine) is used for motion sickness prophylaxis and treatment.
    • It is administered orally or intramuscularly, typically for short periods of intense motion.
    • Transdermal administration is also a method, showing fewer side effects.
    • Side effects include mydriasis, tachycardia, and urinary retention.

    2.3 5-HT3 Receptor Antagonists

    • Granisetron, ondansetron, and palonosetron are examples of 5-HT3 receptor antagonists.
    • These drugs are effective in preventing nausea and vomiting associated with cancer chemotherapy.
    • They can also be used to prevent post-operative nausea and vomiting. Dosage can be oral or intravenous (IV) depending on the severity and type of chemotherapy.

    2.4 Dopamine Antagonists

    • Metoclopramide and Domperidone are examples.
    • Metoclopramide is used to prevent and treat nausea and vomiting associated with migraine, gastroesophageal reflux, hepatic/biliary disorders. Metoclopramide has an additional effect of increasing gastrointestinal motility.
    • Domperidone does not cross the blood-brain barrier (BBB).
    • Useful in treating nausea and vomiting induced by levodopa, cytotoxic treatments, particularly useful in the delayed phase of chemotherapy induced emesis.

    2.5 NK1 Receptor Antagonists

    • Aprepitant and fosaprepitant are examples of NK1 receptor antagonists.
    • Useful in treating the delayed phase of nausea and vomiting induced by chemotherapy, after cytotoxic treatments.

    2.6 Other Antiemetics

    • Nabilone, a synthetic cannabinoid, can reduce vomiting caused by CTZ-stimulating agents. It can be more effective than other antiemetics.
    • High-dose Glucocorticoids (particularly dexamethasone) work in combination with other antiemetics.

    2.7 Antiemetics for specific conditions

    • Meniere's Disease: Prochlorperazine, buccal or intramuscular, and short-term benzodiazepines may be used to treat acute attacks. Betahistine (H3 receptor antagonist) and dexamethasone (immunomodulator) are also used in cases of suspected autoimmune origin
    • Antihistamines are also recommended, as a part of a multi-component treatment strategy.
    • Antipsychotics (Chlorpromazine, Prochlorperazine, Perphenazine): Effective treatment for severe cases where the above methods fail. Limited use to severe cases due to significant side effects. These drugs are administered orally, IV, or rectally. Side effects include sedations, hypotension, and extrapyramidal symptoms, including dystonias and tardive dyskinesias.

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    Description

    This quiz covers the complex process of vomiting, including its pathophysiology and the role of antiemetic drugs. Understand how stimuli affect the medulla's vomit center and learn about the various factors that can lead to emesis. Prepare to explore neurotransmitters involved in this crucial physiological response.

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