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Y2 - CPT > Lecture 18 - Nausea/vomiting Constiption And Diarrhoea > Flashcards

Lecture 18 - Nausea/vomiting Constiption And Diarrhoea Flashcards

1
Q

What is vomiting/emesis?

A

Invlountary, forceful expulsion of gastric contents through the mouth

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2
Q

Where is the vomiting centre located in the brain?

A

Medulla

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3
Q

What is the very general process of vomiting?

A

Deep breath
Glottis closes
Abdo muscles contract (inc Intra abdominal pressure)
Lower oesophageal sphincter relaxes
Retrograde peristalsis of small bowels

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4
Q

What is regurgitation?

A

Often seen in babies
When some feed gets brought back up

Not the same as vomiting

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5
Q

What are the receptors that are found in the vomiting centres in the medulla?

A

Muscarinic ACh
H1(Histamine receptor)
5HT2 (type of serotonin receptor)
NK1 (Neurokinin 1)

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6
Q

What are some stimuli from the cortical centres that may activate the vomiting centre in the medulla?

A

Pain
Visual stimuli
Smells
Stress

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7
Q

How do we manage vomiting or nausea?

A

Conservative management (avoid stimuli)

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8
Q

What part of the brain is stimulated when motion sickness occurs?

A

Vestibular nuclei receive input from labyrinth

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9
Q

What receptors are located in the vestibular nuclei that when are activate lead to motion sickness?

A

Muscarinic ACh
Histamine 1 receptors

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10
Q

What type of drugs are given to treat motion sickness?

A

Muscuranic receptor antagonists (competitive blockers)

H1 antagonists

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11
Q

What are some examples of anti Muscarinic drugs that can be used to treat motion sickness?

A

Hyoscine hydrobromide (works centrally)

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12
Q

What are the adverse reactions of Muscarinic antagonists like hyoscine hydrobromide? (Given for motion sickness)

A

Sedation
Constipation
Dizziness
Dry mouth
Visual problems
Confusion

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13
Q

What are the contraindications for giving Muscarinic antagonists like hyoscine hydrobromide? (Given for motion sickness)

A

Elderly
Glaucoma

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14
Q

What are some importnat drug drug interactions for Muscarinic antagonists like hyoscine hydrobromide? (Given for motion sickness)

A

Anti psychotics

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15
Q

How do H1 antagonists work to treat motion sickness?

A

Works centrally, Act on vomiting centre and vestibular nuclei
Inhibiting histmainergic signals from vestibular system to the CTZ in the medulla

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16
Q

What are some examples of H1 antagonists that treat motion sickness?

A

Cyclizine
Levomepromazine

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17
Q

What are some adverse reactions of H1 antagonists?

A

Sedation
Anti-muscarinic side effects-dry mouth
Constipation
Urinary retention
Blurred vision

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18
Q

What are some contraindications of H1 antagonists?

A

Epilepsy
Glaucoma
Urinary retention
Children
Elderly

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19
Q

What are some sedating H1 antagonists?

A

Diphenhydramine
Cyclizine
Promethazine

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20
Q

What are some non sedating H1 antagonists?

A

Cetirizine (often given for hay fever/allergic rhinitis)
Fexofenadine
Loratidine

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21
Q

Who is motion sickness most common in?

A

Women. And children
Those who have migraines

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22
Q

What are some conservative managements of motion sickness?

A

Hydration
Pistioion in vehicle
Distraction

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23
Q

What are some drugs given for motion sickness?

A

Anitmuscarinics - hyoscine

Anti histamines - Cyclizine, cinnarizine, prochlorperazine

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24
Q

What are some receptors located in the CTZ?

A

D2 (dopamine)
NK1
5HT3

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25
What is an example of a D2 receptor antagonist?
Metoclopramide
26
What affects do D2 receptor anatogonsists like metoclopramide have?
CENTRAL DOPAMINE ANATAGONIST BUT PERIPHERAL CHOLINERGIC AGONIST: Inc ACh at M receptors in gut promoting gastric emptying Inc tone at lower oesophageal sphincter ROS it closes Inc tone and amplitude of gastric contractions Dec tone of pyloric sphincter Inc peristalsis
27
What are some adverse drug reactions of metoclopramide?
Depression Diarrhoea Drowsiness Hypotension Glactorrhoea Extra pyramidal effects (dystopia) Parkinsonism
28
What are some contraindications to metoclopramide?
Post GI surgery Gi obstruction Gi perforation GI haemorrhage
29
What is the D2 receptor antagonist domperidone good for?
Improving lactation in breastfeeding mothers
30
What are the adverse effects of domperidone?
Dry mouth Long QT and VT (cardiac side effects) Loss of libido
31
What are some contraindications of domperidone?
Patients over 60 with arrhythmias
32
What is an example of a D2 receptor antagonist which is an anti-psychotic?
Haloperidol Prochlorperazine, chlorpromazine
33
What part of the brain does Haloperidol act on?
CTZ
34
What are the adverse drug reactions of haloperidol?
Parkinsonism Movement disorders Long QT Arrhythmias Constipation Dry mouth
35
What are the contraindications to Haloperidol?
Parkinson’s disease Cardiovascular disease]] Diabetes Myasthenia gravis
36
What are some adverse reactions of prochlorperazine, chlorpromazine or levomepromazine? Haloperidol is also in this category What type of drugs are these?
D2 receptor antagonists that are. Antipsychotics Drowsiness Dry mouth Movemtn disorders Parkinsonism Long QT Urinary retention
37
What are some contraindications of prochlorperazine, chlorpromazine or levomepromazine? (D2 receptor antagonists which are antipsychotics) + Haloperidol
Elderly patient Parkinson’s disease Cardiovascular disease Diabetes Myasthenia gravis
38
What is the function of NK-1 (neurokinin) receptor antagonists?
Prevents action of substance P at the CTZ and in peripheral nerves Boosts effects of 5HT3 (serotonin) receptor antagonists
39
When are NK-1 receptor antagonists typically used?
Good for chemotherapy particularly for delayed emesis Also has anxiolytic and antidepressant properties
40
What are some examples of NK-1 receptor antagonists?
Aprepitant Fosaprepitant Netupitant
41
What are some adverse reactions of NK-1 receptor antagonists? (Aprepitant)
Constipation Headache Asthenia (weakness not related to lack of sleep)
42
What is the contrainidaiction for Nk-1 receptor antagonists? Aprepitant
Acute porphyrias (conditions affecting enzymes involved in haem synthesis)
43
What part of the brain do corticosteroids act on?
CTZ But may also have properties of D2 receptor antagonists
44
What types of vomiting are corticosteroids good for?
Perioperative nausea and vomiting Chemotherapy related vomiting Palliative vomiting
45
What are some examples of corticosteroids used for anti emetics?
Dexamethosome Methylprednisolone
46
What are some adverse effects of corticosteroids? (Dexamethasome and methylprednisolone)
Insomnia Osteoporosis Inc weight Inc appetite Inc blood sugar Cushing’s syndrome
47
What are some contraindications to using corticosteroids for anti-emetics?
Osteoporosis Diabetes Mellitus Peptic ulcers
48
Where do cannabinoids act?
CTZ Last line use for chemotherapy
49
What are the adverse drug reactions to cannabinoids?
Confusion Depression Drowsiness Dizziness Movement disorders Psychosis Tremor Visual impairment
50
What are the contraindications to cannabinoids?
Elderly patients Heart disease Hx of psychiatric disorder
51
what is an example of a cannabinoid?
Nabilone
52
What are some metabolic causes of post-operative vomitting?
Uraemia DKA Hypercalcaemia
53
What are some potential drugs used to treat post-operative vomiting?
Metoclopramide Hyoscine (anti-Muscarinic)
54
What is ileus?
Condition caused by lack of movemtn of smooth muscle in the intestine leading to obstructions and blockages
55
What are the first things you do when treating pregnancy induced vomiting? (Hyperemesis gravidarum)
Fluids replacement Anti-histamines (promethazine/cyclizine) Phenothiazine - prochlorperazine Ondansetron Steroids Metoclopramide Thiamine replacetn
56
What part of the vomiting pathway is involved in nausea and vomiting involving gut problems?
Enterochromaffin cells (toxic chemicals in gut) Vagal afferents (convery signals from gut to brainstem)
57
What receptors are stimulated with GI problems in the enterochromaffin cells and vagal afferents leading to nausea or vomting?
D2 (dopamine) NK1 (neurokinin 1) 5HT3 (serotonin)
58
What is the main category of drug that is used to treat nausea/vomitng due to GI problems and why?
5-HT3 antagonists (serotonin) Most serotonin receptors are found in the gut
59
When is serotonin produced in the gut and what is its action?
Made by enterochromaffin cells in response to parasympathetic stimulation Serotonin excites enteric neurones increasing gut motility, increasing gut secretions and regulates appetite
60
What is an example of a 5-HT3 antagonist to treatGI vomitting?
Ondansetron
61
What are the central and peripheral effects of a 5-HT3 (serotonin) antagonist? What is an example of this drug?
Ondansetron Peripherally = reduces gut motility and reduces gut secretions Centrally = Inhibits CTZ
62
What are the adverse reactions of Ondansetron (5-HT3 antagonists)?
Constipation Headache Elevated liver enzymes Long QT syndrome Extra-pyramidal effects (dystonia) Parkinsonism
63
What are the contraindications of 5-HT3 antagonists (Ondansetron)?
Subacute abdominal obstruction Susceptible to long QT
64
What is the 1st line drug treatment for an anti-emetic when a patient has a bowel obstruction?
Cyclizine
65
How do you non pharmacologically treat bowel obstruction?
NG tube
66
Go to slide 34 and label the pathway
67
What is considered constipation?
Change in consistency and reduced frequency of stools
68
How is constipation managed before drugs?
Healthy diet (dietary fibre intake) Fluid intake Exercise Toilet routing and positioning
69
What is fecal impaction?
When theres a hardened bit of stool blocking the rectum or colon preventing faeces from being passed
70
How do bulk-forming laxatives work?
Polysaccharide polymers (acting like fibre) dont get digested So increases the oncotic pressure in teh gut lumen promoting peristalsis and improving faecal consistency
71
What are some examples of bulk-forming laxatives?
Isphagula husk Methyl cellulose
72
What are some examples of faecal softeners?
Sodium docusate Arachis oil enema Liquid paraffin
73
What are some examples of osmotic laxatives?
Lactulose Macrogol
74
How do osmotic laxatives work?
Laxatives poorly absorbed in the gut so increase oncotic potential in gut drawing water in
75
How do laxative stimulants work?
Increasing electrolyte and water secretion by the mucosa and by increasing peristalsis by stimulating enteric nerves
76
What are some examples of laxative stimulants?
Bisacodyl Sodium picosulfate Senna Glycerol suppositories
77
What are some drug causes of diarrhoea?
Domperidone (increases GI motility) Metoclopramide (increases gastric emptying and motility) Naloxegol (Mu opioid antagonist that is similar to Naloxone)
78
What are some causes of diarrhoea?
Infection (Cholera) Toxins/drugs Radiotherapy Anxiety
79
How do you treat diarrhoea?
Treat the complication: -oral rehydration -IV fluids Treat the cause: -travellers diarrhoea -campylobacter -salmonella Reduce bowel motility and increase transit time
80
What are some drugs used to treat diarrhoea?
Opioids Loperamide
81
How do opioids work to treat diarrhoea?
Agonises Mu opioid and delta receptors Side effect is constipation (its a secondary action)
82
What are some adverse reactions of opioids?
Paralytic ileus Constipation Nausea and vomitng Reduced Respiraoty rate (RESP DEPRESSION) Sedation Addiction and withdrawal syndromes
83
What are some contraindications of opioids?
Impaired resp function Adrenocortical insufficiency Elderly patients
84
How does loperamide work to treat diarrhoea?
A type of Mu opioid receptor agonsit Binds specifically to the Mu opioid receptors in the Myenteric plexus Decreases tone of longitudinal and circular smooth muscle Reduces peristalsis but increases segmental contractions Decreases colonic mass movement by suprresing gastrocolic reflex
85
What are the adverse reactions of loperamide?
Headache Nausea Drowsiness Dizziness Dry mouth
86
What are the contraindications of loperamide?
Abdominal pathologies Children under 12

Y2 - CPT (30 decks)

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