252 Pharmacology - Antiemetic Drugs Flashcards

1
Q

Definition of nausea.

A

Sensation often leading to the urge to vomit

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2
Q

Definition of emesis (vomiting).

A

Forcible emptying of gastric and, occasionally, intestinal contents.

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3
Q

List the various classifications of antiemetic and antinausea drugs.

A
  • Anticholinergic drugs
  • Antihistamines (histamine 1 [H1] receptor blockers)
  • Antidopaminergic drugs
  • Neurokinin antagonists
  • Prokinetic drugs
  • Serotonin blockers
  • Tetrahydrocannabinoids
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4
Q

What is the mechanism of action for most antiemetic or antinausea drugs?

A

Most work by blocking one of the vomiting pathways, thus blocking the stimulus that induces vomiting.

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5
Q

What is the mechanism of action for anticholinergic antiemetiic/antinausea drugs?

A
  • Bind to and block acetylcholine receptors in the inner ear labyrinth
  • Block transmission of nauseating stimuli to CTZ
  • Also block transmission of nauseating stimuli from the reticular formation to the vomiting centre
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6
Q

Define chemoreceptor trigger zone (CTZ)

A

The area of the brain that is involved in the sensation of nausea and the action of vomiting.

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7
Q

What is the vomiting centre (VC)?

A

The area of the brain that is involved in stimulating the physiological events that lead to nausea and vomiting.

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8
Q

What are the indications for anticholinergics?

A
  • Motion sickness
  • secretion reduction before surgery
  • nausea and vomiting
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9
Q

What are the indications for antihistamines?

A
  • Motion sickness
  • Nonproductive cough
  • Sedation
  • Rhinitis
  • Allergy symptoms
  • Nausea and vomiting
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10
Q

What are the indications for antidopaminergics?

A
  • Psychotic disorders
  • intractable hiccups
  • nausea and vomiting
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11
Q

What are the indications for prokinetics?

A
  • Delayed gastric emptying
  • Gastroesophageal reflux
  • Nausea and vomiting
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12
Q

What are the indications for serotonin blockers?

A
  • Nausea and vomiting associated with chemotherapy
  • Postoperative nausea and vomiting
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13
Q

What are the indications for tetrahydrocannabinol?

A
  • Nausea and vomiting associated with chemotherapy
  • Anorexia associated with weight loss in patients with AIDS and cancer
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14
Q

What are some causes of N and V?

A
  • Chemotherapy
  • Postoperative
  • Anesthesia
  • General
  • Inner ear infection
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15
Q

What class is scopolamine?

A

anticholinergic

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16
Q

What is the mechanism of action of anticholinergic antiemetics?

A
  • Bind to and block acetylcholine receptors in the inner ear labyrinth
  • Block transmission of nauseating stimuli to CTZ
  • Also block transmission of nauseating stimuli from the reticular formation to the vomiting centre
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17
Q

What is the mechanism of action of antihistamine antiemetic drugs?

A
  • Inhibit acetylcholine by binding to H1 receptors
  • Prevent cholinergic stimulation in vestibular and reticular areas, thus preventing nausea and vomiting
18
Q

What class of drug are •dimenhydrinate (Gravol®) and diphenhydramine (Benadryl®)?

A

antihistamines

19
Q

What is the mechanism of action of antidopaminergic antiemetic drugs?

A

Block dopamine receptors in the CTZ

20
Q

What class of drug is •prochlorperazine (Proclorazine®)?

A

antidopaminergic

21
Q

What is the mechanism of action of neurokinin receptor antagonists?

A
  • Inhibit substance P/neurokinin 1 receptors in the brain stem
  • Used in conjunction with serotonin blockers and glucocorticoids
  • Use augments the serotonin blockers and glucocorticoids to inhibit acute and delayed phases of chemotherapy-induced emesis
22
Q

What class does aprepitant belong to?

A

neurokinin receptor antagonist

23
Q

What is the mechanism of action of prokinetic drugs?

A
  • Block dopamine receptors in the CTZ
  • Cause CTZ to be desensitized to impulses it receives from the gastrointestinal tract
  • Also stimulate peristalsis in gastrointestinal tract, enhancing emptying of stomach contents
24
Q

What class does metoclopramide belong to?

A

prokinetic drugs

25
Q

What is the most significant thing to be watching for with metoclopramide?

A

Long-term use may cause irreversible tardive dyskinesia

26
Q

What is the mechanism of action for serotonin blockers?

A
  • Block serotonin receptors in the gastrointestinal tract, CTZ, and vomiting centre
27
Q

What class of drug does ondansetron belong to?

A

serotonin blockers

28
Q

What is the mechanism of action of tetrahydrocannabinoids?

A
  • Major psychoactive substance in marihuana
  • Inhibitory effects on reticular formation, thalamus, cerebral cortex
  • Alter mood and body’s perception of its surroundings, which may help relieve nausea and vomiting
29
Q

What is doxylamine succinate used for?

A

used for morning sickness with pregnancy

30
Q

What is pyridoxine hydrochloride used for?

A

combination known as Diclectin – used for morning sickness – N & V - during pregnancy

31
Q

What is ginger used for in relation to nausea and vomiting?

A
  • Used for nausea and vomiting, including that caused by chemotherapy, morning sickness, and motion sickness
  • Adverse effects
    • Anorexia, nausea and vomiting, skin reactions
32
Q

What drug interactions exist for ginger?

A
  • May increase absorption of oral medications
  • Increase bleeding risk with anticoagulants
33
Q

What contraindications are there for scopolamine?

A
  • glaucoma (due to the pupil dilation effect; may alter intraoccular pressure)
34
Q

What forms is scopolamine available in?

A
  • injectable
  • patch (applied every 72 hours, onset is 4 hours)
35
Q

True or false: antihistamines can have a paradoxical effect on pediatric patients?

A

True. It can make them hyperactive

36
Q

What are the contraindications for prochlorperazine?

A
  • Hypersensitivity to phenothiazines
  • Those in a coma
  • Those with seizures, encephalopathy, or bone marrow depression
37
Q

What forms does prochlorperazine come in?

A

Oral and injection

38
Q

What are contraindications for metoclopramide?

A
  • seizure disorders
  • pheochromocytoma
  • breast cancer
  • GI obstruction
39
Q

What is a warning when using ondansetron?

A

Risk of dysrhythmias, particularly when faster infusion rates are used.

40
Q

What effect does aprepitant have on warfarin?

A

Induces the metabolism of warfarin sodium and the INR needs to be checked before each cycle.

41
Q

What are contraindications of doxylamine succinate and pyridoxine hydrochloride?

A
  • those with risk of asthmatic attack
  • patients with narrow angle glaucoma
  • stenosing peptic ulcer
  • pyloroduodenal obstruction
  • bladder-neck obstruction
  • those taking monoamine oxidase inhibitors
42
Q

What assessments should be done relative to antidopaminergic antiemetic drugs?

A
  • Skin turgor and tongue for longitudinal furrows
  • Blood pressure and pulse rate (related to effects of orthostatic hypotension and tachycardia)