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MD1140 Pharmacology > Drugs Used in Nausea and Vomiting > Flashcards

Drugs Used in Nausea and Vomiting Flashcards

1
Q

List SEVEN major classes of drugs used for the treatment of nausea and vomiting.

A

(1) Serotonin 5-HT3 antagonists
(2) Corticosteroids
(3) Neurokinin receptor antagonists
(4) Dopamine receptor antagonists
(5) Muscarinic receptor antagonists
(6) H1 histamine receptor antihistamines
(7) Benzodiazepines

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2
Q

Name TWO examples of antiemetic serotonin 5-HT3 antagonists

A

Ondansetron, granisetron, palonosetron, and other *setrons

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3
Q

Name an example of (1) a first-generation and (2) a second-generation 5-HT3 antagonist anti-emetic. State the half-life of these drugs.

A

(1) First-generation:
* Ondansetron (half-life 4-9 hrs)
(2) Second-generation:

  • Granisetron: half-life 9-12 hrs in cancer patients
  • Palonosetron: half-life 40-50 hrs
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4
Q

Briefly describe the mechanism of action of 5-HT3 antagonist antiemetics and describe their use in the treatment of chemotherapy-induced nausea and vomiting.

A
  • Act at 5-HT3receptors primarily in the GIT
  • CNS 5-HT3receptors do not appear to play an important role in actions in nausea and vomiting
  • Efficacy enhanced by combination with a corticosteroid and NK1-receptor antagonist
  • Intravenously 30 min before or orally 1 hour before chemotherapy to prevention of acute chemotherapy-induced nausea and vomiting (CINV).
  • Generally not effective for delayed nausea and vomiting (>24 hr after chemotherapy)
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5
Q

Name an example of a corticosteroid used in the treatment of chemotherapy-induced nausea and vomiting.

A

Dexamethasone, methylprednisolone

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6
Q

Briefly discuss the adverse effects of corticosteroids used as antiemetics for chemotherapy-induced nausea and vomiting.

A

Major concerns / adverse effects:

  • Unlikely to occur with short-term use
  • Higher doses or longer-term use (> 2 weeks) may cause iatrogenic Cushing’s syndrome, including:
    • Redistribution of fat (rounded face)
    • Muscle wasting
    • Thinning of skin, easy bruising
    • Hyperglycaemia, later diabetes
    • Osteoporosis
    • Immunosuppression
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7
Q

Name an example of a dopamine receptor antagonist used as an antiemetic.

A

Metoclopramide

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8
Q

Describe the mechanism of action of dopamine receptor antagonists as antiemetics

A

Dopamine, especially dopamine D2, receptor antagonism in the chemoreceptor trigger zone (CTZ).

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9
Q

Discuss the adverse effects of dopamine receptor antagonists.

A
  • Major concerns / adverse effects:
  • Extrapyramidal side effects:
    • Restlessness, dystonia, and parkinsonian symptoms
    • The elderly are especially susceptible
    • On long-term treatment, irreversible tardive dyskinesia can develop
      • Therefore, only used short-term
  • Elevated prolactin levels can cause:
    • Galactorrhoea, gynaecomastia, impotence and menstrual disorders
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10
Q

What are the recommended options for the treatment of acute nausea and vomiting induced by a chemotherapy regimen expected to have low emetogenic risk?

A

A 5-HT3 receptor antagonists OR dexamethasone OR a dopamine receptor antagonist

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11
Q

What are the recommended options for the treatment of acute nausea and vomiting induced by a chemotherapy regimen expected to have moderate emetogenic risk (other than carboplatin)?

A

5-HT3 receptor antagonist AND dexamethasone

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12
Q

What are the recommended options for the treatment of acute nausea and vomiting induced by a chemotherapy regimen expected to have a high emetogenic risk or carboplatin?

A

5-HT3 receptor antagonist AND dexamethasone AND neurokinin NK1 receptor antagonist

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13
Q

Name an example of a neurokinin 1 (NK1) receptor antagonist used to treat nausea and vomiting.

A

Aprepitant, fosaprepitant or any other *pitant

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14
Q

Discuss the routes of administration of aprepitant and fosaprepitant.

A

Aprepitant is administered oral. Fosaprepitant is an intravenously administered prodrug of aprepitant.

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15
Q

Briefly explain the mechanism of action of neurokinin NK1 receptor antagonists in treating nausea and vomiting.

A

Neurokinin NK1 receptor antagonists directly antagonize NK1 receptors in the chemoreceptor trigger zone of the area postrema.

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16
Q

List major adverse effects and concerns with the use of neurokinin NK1 receptor antagonists

A

Major concerns / adverse effects:

  • Fatigue, dizziness, diarrhoea
  • Metabolism by CYP3A4
    • Interaction with various chemotherapeutic agents (e.g., docetaxel, etoposide, irinotecan, imatinib, vinblastine)
    • Drugs that inhibit CYP3A4 may influence plasma levels e.g., ketoconazole, clarithromycin, ritonavir, verapamil
17
Q

Name THREE examples of mixed dopamine, muscarinic and/or histamine receptor antagonists

A
  • Phenothiazines: prochlorperazine, promethazine
    • Dopamine, muscarinic & histamine receptor antagonism
  • Butyrophenones: droperidol
    • Dopamine receptor antagonism and weak histamine receptor antagonism
  • Atypical antipsychotic: olanzapine
    • Dopamine, muscarinic & histamine receptor antagonism
    • Also 5-HT3 receptor antagonism
18
Q

List major concerns with and adverse effects of mixed dopamine, muscarinic and/or histamine receptor antagonist antiemetics.

A

Main concerns / adverse effects:

  • Sedative (due to antihistamine effects)
  • Extrapyramidal side-effects [EPS] (e.g. Parkinsonian motor adverse effects)
    • Olanzapine: Controls CINV delayed nausea with less EPS
  • Hypotension
  • Droperidol: prolongation of the QT interval
19
Q

Name ONE example of a benzodiazepine used to manage anticipatory nausea and vomiting.

A

Lorazepam, diazepam

20
Q

Briefly explain the use of benzodiazepines in the treatment of nausea and vomiting.

A
  • Binding to an allosteric site on GABAA receptors increases chloride conductance
  • Anxiolytic
  • Reduce anticipatory vomiting or vomiting caused by anxiety
21
Q

Discuss the major concerns with and adverse effects of benzodiazepines.

A

Major concerns / adverse effects:

  • Sedative / hypnotic
  • Additive effects with other sedative drugs and CNS depressants e.g., antidepressants, alcohol and opioids
    • Respiratory depression on overdose
  • Avoid during pregnancy, especially first trimester (risk of cleft palate)
22
Q

Name TWO drugs commonly used for the treatment of motion sickness induced nausea and vomiting.

A

Scopolamine (also known as hyoscine), diphenhydramine

23
Q

Briefly discuss the mechanisms of action and adverse effects of scopolamine.

A

Mechanisms:

  • Muscarinic receptor antagonist (action in vestibular system and vomiting centre)
  • Used for prevention of motion sickness

Major concerns / adverse effects:

  • Anticholinergic(parasympatholytic) adverse effects:
    • Dry mouth, blurring of vision, constipation
  • High incidence of adverse effects when given orally therefore often administered by transdermal patch
24
Q

Briefly discuss the mechanisms of action and adverse effects of diphenhydramine when used as an antiemetic.

A

Mechanisms:

  • H1 histamine receptor antagonism (vomiting center and ?vestibular system)
  • M1 cholinergic receptor antagonism (vomiting centre and vestibular system)
  • Particularly useful for the treatment of motion sickness
  • Sedative effects of diphenhydramine may also be useful in treatment of emesis due to chemotherapy

Major concerns / adverse effects:

  • Sedative due to antagonism of H1 receptors
  • Anticholinergic (parasympatholytic) adverse effects:
  • Dry mouth, blurring of vision, constipation

MD1140 Pharmacology (12 decks)

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