Antiemetic & anticonstipation Flashcards

1
Q

how we vomit

A
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2
Q

what triggers the emesis? where do they act?

A
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3
Q

what drugs r used and where do they act?

A
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4
Q

Antihistamines

where and how they work?

indications?

SE?

contraindicated in?

A

Cyclizine, Levomepromazine, Cinnirazine, Promethazine Diphenhydramine,

• Centrally

Acts on the VN

Inhibits histaminergic signals from the vestibular system to the CTZ in medulla

Side effects

• Sedation
• Excitation
• Antimuscarinic–dry mouth, constipation, urinary retention,
• Cardiactoxicity(longQT interval)

Indications:

  • Motion sickness – long plane journeys*
  • Promethazine – morning sickness in pregnancy*

Not good for:-

• Cyclizine – little old ladies and children

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5
Q

what agents act on visceral afferents in the gut?

A
  • 5HT3 receptor Antagonists
  • D2 receptor antagonists
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6
Q

Serotonin (5HT) function in the gut

A
  • 95% serotonin in the body is located in the gut
  • Produced by the enterochromaffin cells
  • In response to parasympathetic stimulation, serotonin excited enteric neurones
  • Smooth muscle contraction increases motility (except in the stomach)
  • Increases gut secretions
  • Regulates appetite
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7
Q

5HT3 receptor Antagonists

A

Ondansetron, Granesitron, Palonosetron

(dan is happy)

Peripherally
• Reduces GI motility
• Reduces GI secretions

Centrally
• Acts to inhibit the CTZ

Indication
• Almost everyone – it’s often the 1st line treatment

Side effects - uncommon

  • Constipation
  • Headache
  • Elevated liver enzymes
  • Long QT syndrome
  • Extra-pyramidal
  • effects – dystonia, parkinsonism
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8
Q
  • D2 receptor antagonists

(acting on visceral afferents in the gut )

A

acting on visceral afferents in the gut

Metaclopramide

  • Increases Ach at muscarinic receptors in the gut
  • Promotes gastric emptying

↑ tone at lower oesophageal sphincter so it closes

↑ tone and amplitude of gastric contractions

↓ tone of pylorus so it opens

• Increases peristalsis

Indication-

  • GORD
  • Ileus

Side effects

  • Galactorrhoea via prolactin release
  • Extra-pyramidal effects – dystonia, parkinsonism

DONT USE IF RISK OF OBSRUCTION OR PERFORATION

Domperidone

Similar mechanism as metoclopramide

BUT has increased risk of significant cardiac side effects.

  • Good for:-
  • Improving lactation in breastfeeding mothers

Side effects

  • Sudden cardiac death (long QT and VT)
  • Galactorrhoea
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9
Q

D2 receptor antagonists

acting on the CTZ

A

Prochlorperazine, Chlorpromazine, Levomepromazine, Haloperidol

May also block H1 and Muscarinic receptors

Indication

  • Motion sickness, vertigo.

Prochlorperazine in pregnancy

Haloperidol

Act on the CTZ

Indication:- chemotherapy and palliation

Side effects

• Extra-pyramidal effects – dystonia, parkinsonism

  • Sedation
  • hypotension
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10
Q

Corticosteroids

where and how they work?

indications?

SE?

A

Dexamethasone, Methylprednisolone

Assumed to act on the CTZ
• May also have properties of D2 receptor antagonists

Indications
• Perioperative nausea and vomiting

  • Chemotherapy
  • Palliation

Side effects

• Insomnia

↑ appetite

↑ blood sugar

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11
Q

Cannabinoids

  • where and how they work?
  • indications?
  • SE?
A

Nabilone

  • Assumed to act on the CTZ
  • Good for chemotherapy - used as last line

Side effects
• Dizziness
• Drowsiness

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12
Q
  • Neurokinin 1 receptor antagonists
  • where and how they work?
  • indications?
  • SE?
  • contraindicated in?
A

Aprepitant, Fosaprepitant, Netupitant

  1. Prevent the action of substance P at CTZ and in peripheral nerves
  2. Boosts effects of 5HT3 receptor antagonists
  3. Anxiolytic and antidepressant properties

indication:

chemotherapy – particularly for delayed emesis

Side effects
• Headache
• Diarrhoea/constipation

• Stevens-Johnson

syndrome

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13
Q

Motion Sickness

A
  1. Hyoscine hydrobromide is 1st line

but if ur sailing or driving a boat and u cant be sedated…..

  1. Cinnirazine typically has fewer side effects
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14
Q

what r Prokinetics & Useful for GORD& Ileus ?

when should it not be used?

A

Domperidone, Metaclopramide (Cisapride)

Don’t use
• Obstruction
• Risk of perforation

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15
Q

most gut pathologies or obstruction causing emesis?

A
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16
Q

what is Hyperemesis Gravidarum? what causes it? risk in? treatment>

A
  • Rapid rise in ẞhcg stimulates the CTZ
  • Typically weeks 4-16 but may continue beyond
  • Higher risk with multiple pregnancies
  • More than just ‘morning sickness’ – dehydration, 5% weight loss, electrolyte imbalance, urinary ketones $
17
Q

Chemotherapy treatment antiemetic

A
18
Q

Post operative nausea and vomiting managment?

A
19
Q

antifidiharreal?

A

Opioid receptor agonist

Loperamide

– specific to μ receptors in the myenteric plexus

  1. Decreases tone of longitudinal and circular smooth muscle
  2. Reduces peristalsis but increases segmental contractions
  3. Decreases colonic mass movement by supressing gastrocolic reflex.

Side effects

  • Paralytic ileus
  • N & V
  • Sedation & Addiction (codeine and morphine)
20
Q

Types of anticonstipating drugs?

A
  • Osmotic
  • Stimulants/irritants
  • bulk forming
  • stool softeners
  • lubricants
21
Q

Osmotic Laxatives

A

Increase the amount of water in the large bowel

Draw fluid in>> Lactulose

OR
Retain the fluid they came with>> Macrogols/Movicol

22
Q

Stimulant Laxatives

A

Bisacodyl, Sodium Picosulphate, Senna, Co-Danthromer, Docusate Sodium (Glycerin)

  1. Increase intestinal motility May be given orally or per rectum
  2. Docusate sodium acts as stimulant and stool softener Glycerin suppositories cause rectal irritation and lubrication
23
Q

Bulk forming laxatives

A

Ispaghula husk, Methylcellulose

form gels in the colon causing water retention & distension! > oincreased peristalsis

24
Q

Stool Softeners / lubricants

A

Docusate sodium, Glycerin suppository, Arachis oil ,Liquid paraffin, mineral oil

  1. Decrease surface tension of stool
  2. Increase penetration of fluid into stool

stool softeners takes days to work, often used as prohpylaxis rather than acute treatment