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SP- Week 6 > Anti-emetic Drugs > Flashcards

Anti-emetic Drugs Flashcards

1
Q

“Nausea & vomiting are triggered by

A
  • drugs (anticancer, opioids, general anaesthetics,
    digoxin)
     Motion sickness
     Early pregnancy
     Infections
     Other disease states ex. Migraines
    .
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2
Q

Nausea & vomiting are triggered by
Which drugs

A

anticancer, opioids, general anaesthetics,
digoxin

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3
Q

REFLEX MECHANISM OF VOMITING

A

-Defensive response to rid of toxic material ‘
- Release of mediators from enterochromaffin cells in the GI tract e.g. 5-HT (serotonin)
- Transmit signals via vagal afferent fibers to the
central nervous system
- Regulated centrally by the vomiting centre in
the medulla

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4
Q

Solitary tract nucleus
MoA

A

Transmits signals from periphery (via vagal and
cranial afferent fibers) to the vomiting center

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5
Q

Chemoreceptor trigger zone (CTZ): permeable
MoA

A

 Receives input from
 Labyrinth in the inner ear
 GI tract
 Chemicals in the blood

 Main site of action of many emetic and anti-
emetic drugs

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6
Q

Neurotransmitters involved in vomiting

A

 Acetylcholine
 Histamine
 5-hydroxytryptamine (5-HT)
 Dopamine
 Substance P (Neurokinin-1 receptors)
 Endocannabinoids

(Pharmacologically it is easier to control vomiting than nausea )

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7
Q

ANTI-EMETIC DRUGS

Clinical indications

A

 Adjunct to cancer chemotherapy
 Motion sickness
 Vestibular disorders
 Morning sickness of pregnancy
 In general, all drugs should be avoided during
the first three months of pregnancy, if possible

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8
Q

CLASSES OF ANTI-EMETIC DRUGS
(7)

A

:  Histamine receptor antagonists
 Muscarinic receptor antagonists
 Serotonin receptor antagonists
 Dopamine antagonists
 NK 1 receptor antagonists
 Cannabinoids
 Glucocorticoids

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9
Q

H1 RECEPTOR ANTAGONISTS
Exs.

A

Cinnarizine, cyclizine, promethazine, diphenhydramine,
meclizine

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10
Q

H1 RECEPTOR ANTAGONISTS
Clinical uses

A

“Effective against nausea and vomiting
arising from many causes
 Motion sickness: prevention and treatment
 Post-op emesis
 Severe nausea and vomiting in pregnancy
None is effective against substances that act directly on the CTZ

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11
Q

Chief unwanted effects + other
Of H1 receptor antagonists

A

 Drowsiness and sedation
 Cyclizine is the least sedating drug

Other adverse effects: blurred vision, dry mouth, urinary retention (anti-cholinergic); headache (a1 -adrenergic receptor blockade)

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12
Q

MUSCARINIC RECEPTOR ANTAGONISTS
Ex + CI

A

Hyoscine (scopolamine)

Clinical Use: Prophylaxis and treatment of
motion sickness

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13
Q

Hyoscine (scopolamine)

Adverse Effects

A

Dry mouth and blurred
vision are the most common
 Less sedative action than antihistamines

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14
Q

‘5HT3 (serotonin) RECEPTOR ANTAGONISTS
Exs.

A

Granisetron, ondansetron, palonosteron

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15
Q

Serotonin antagonists exs.

Clinical Uses

A

 Nausea and vomiting post-op ‘
 Nausea and vomiting caused by radiation therapy or
cytotoxic drugs (most widely used drugs)
! Especially for acute emesis (within 24 hours)

! Not useful in motion sickness

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16
Q

-5HT3 RECEPTOR ANTAGONISTS

Primary site of action + Unwanted effects

A

-Primary site of action: CTZ
-Unwanted effects
 Headache, flushing, constipation, QT interval
prolongation, serotonin syndrome
 Relatively uncommon

17
Q

DOPAMINE ANTAGONISTS
Exs.

A

Antipsychotic agents
Chlorpromazine, prochlorperazine, haloperidol

18
Q

‘DOPAMINE ANTAGONISTS
, Clinical Uses:

A

more severe (or refractory) nausea and vomiting
 Associated with cancer, radiation therapy, cytotoxic drugs (late emetic phase), opioids, anaesthetics and other drugs

19
Q

DOPAMINE ANTAGONISTS
-MOA

A

 Antagonists of the dopamine D2 receptors in the CTZ
 Also block histamine and muscarinic receptors
-
May be of value in motion sickness

20
Q

DOPAMINE ANTAGONISTS
Common AE

A

 Sedation
 Hypotension
 Galactorrhea
 Extrapyramidal symptoms: Dystonias, tardive dyskinesia, Parkinsonian-
like symptoms

21
Q

‘METOCLOPRAMIDE
MoA

A

D2 receptor antagonist
-Acts centrally on the CTZ

22
Q

METOCLOPRAMIDE
, Clinical Uses

A

 Useful in delayed emesis in chemotherapy and in radiotherapy
 Symptomatic treatment in nausea and vomiting (e.g. migraine,
gastroenteritis)

23
Q

-METOCLOPRAMIDE

Peripheral action on GI tract

A

Increases motility of the oesophagus, stomach and intestine
(prokinetic)
Adds to the anti-emetic effect in states of reduced gut motility (e.g.
opioids, diabetic gastroparesis)
Treatment of gastroparesis (and GOR

24
Q

METOCLOPRAMIDE AE

A

 Disorders of movement ‘
 Spasmodic torticollis (involuntary twisting of
the neck)
 Occulogyric crises (involuntary upward eye
movements)
 Motor restlessness
 Fatigue
 Galactorrhoea and disorders of menstruation

25
Q

METOCLOPRAMIDE Contraindinicated

A

Contraindicated in bowel obstruction and
Parkinson’s disease

26
Q

‘DOPAMINE ANTAGONISTS

A

Domperidone

27
Q

Domperidone
Clinical ind.

A

Similar to metoclopramide

-, Used to treat vomiting due to cytotoxic
therapy as well as GI symptoms

28
Q

Domperidone MoA

A

‘ Does not readily penetrate the blood–brain
barrier
 Less prone to producing central side effects
 May cause QT interval prolongation

29
Q

OTHER ANTI-EMETICS

A

NK1 ReceptorAntagonists
Glucocorticoids
Cannabinoids

30
Q

-NK1 Receptor Antagonists
MoA

A

Block substance P Not well- (NK1) receptors in the
CTZ and vomiting centre

31
Q

Nk1 receptor antagonists
Clinical use

A

Inhibit late phase of emesis caused by cytotoxic drugs (typically combined with a 5-HT3 antagonist and dexamethasone)

32
Q

Nk1 receptor antagonists Exs.

A

aprepitant(oral), fosaprepitant (IV)

33
Q

Cannabinoids Exs.

A

dronabinol, nabilone

34
Q

Cannabinoids MoA

A

Decrease vomiting at the CTZ through stimulation of CB1(cannabinoid) receptors

35
Q

Cannabinoids Clin. Ind.

A

Chemo-induced emesis, where other drugs have failed

36
Q

Glucocorticoids Exs

A

-dexamethasone

37
Q

Glucocorticoids clin use

A

Chemo-induced emesis (either alone or in combination with a phenothiazine, ondansetron, aprepitant)

SP- Week 6 (3 decks)

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