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Semester 5 - Farmocology > Session 13 - Shitting 'n Sickness > Flashcards

Session 13 - Shitting 'n Sickness Flashcards

1
Q

What is management of peptic ulcer if due to h.pylori

A

PPI (omeprazole)
Antibiotics (Clarithromycin/amoxicillin)
H2 antagonist - Cimetidine

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2
Q

What are four defensive aspects of the gastric mucosa

A

Epithelial integrity
Cell replication and restitution
Mucous membrane barrier
Vascular supply

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3
Q

What are the three main agressive factors of the gastric mucosa

A

Acid
H. Pylori
Drugs (NSAIDs)

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4
Q

Outline the phases of control of gastric secretion

A

Cephalic
- Sensory stimulus and act of swallowing stimulates Ach release, stimulating parietal cells
Gastric
- Distension, further stimulating Ach release
- Buffering of stomach acid stimulates gastrin release
- Small peptides cause upregulation of gastrin
Intestinal
- CCK and GIP released once chyme enters duodenum, which inhibit gastrin.
- Low pH also inhibits gastrin

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5
Q

Outline the plexi of the enteric nervous system (four), including where they can be found

A 
o	Auerbach’s Plexus
	Between circular and longitudinal muscle layers
o	Meissner’s Plexus
	Submucosa
o	Henle’s Plexus
	Circular muscle adjacent to submucosa
o	Cajal’s Plexus
	Circular muscle adjacent to longitudinal muscle
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6
Q

How do the plexi control the GI tract?

A

Together these autonomic gonglionated plexi control the functioning of the GI tract through complex local reflex connections between sensory neurones, smooth muscle, mucosa and blood vessels.
Extrinsic parasympathetic fibres from the vagus are excitatory, extrinsic sympathetic fibres are inhibitory.

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7
Q

What are the three main reflexes of the GI tract

A

o Intestino-intestinal inhibitory reflex
 Distension of one intestinal segment causes complete intestinal inhibition (Peristalsis)
o Anointestinal Inhibitory Reflex
 Distension of anus causes intestinal inhibition
o Gastrocolic and Duodenocolic Reflexes
 Stimulates motility after material has entered the stomach or duodenum

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8
Q

What are laxatives used for?

A

To hasten transit time in the gut and encourage defecation. Laxatives are used to relieve constipation and to clear the bowel prior to medical and surgical procedures.

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9
Q

What is the best regulator of frequency and volume of stool?

A

Diet

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10
Q

What are four different types of laxatives?

A

o Bulk Laxatives
o Faecal Softeners
o Osmotic Laxatives
o Irritant / Stimulant Laxatives

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11
Q

What would you give in soft faeces constipation

A

Stimulant laxatives

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12
Q

What would you give in history or DRE hard faeces

A

Osmotic laxatives

Bulk-forming laxatives

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13
Q

What is the indication for a bulk laxative?

A

Constipation, particularly when hard stools are present

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14
Q

What are four contraindications for bulk laxatives?

A

 Dysphagia
 Intestinal obstruction (Adhesions, ulceration)
 Colonic atony
 Faecal impaction

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15
Q

What is the mechanism of action for bulk laxatives?

A

 Increases the volume of the non-absorbable solid residue in the gut, distending the colon and stimulating peristaltic movement.

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16
Q

Give three ADRs of bulk laxatives

A

 Flatulence
 Abdominal distension
 GI obstruction

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17
Q

What is necessary for the patient to do while taking bulk laxatives?

A

Have a normal fluid intake

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18
Q

Give a type of faecal softener

A

Glycerol (given as suppository

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19
Q

Give four indications for faecal softeners

A

 Constipation
 Faecal impaction
 Haemorrhoids
 Anal fissures

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20
Q

What group should faecal softeners not be used on/

A

Children less than 3

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21
Q

What is the mech of action of faecal softeners?

A

Lubricate and softens stools

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22
Q

What is the mechanism of action of an osmotic laxative?

A

 Increase water content of the bowel via osmosis
 Lactulose – Disaccharide (galactose/fructose) that cannot be hydrolysed by digestive enzymes. The fermentation of lactulose by colonic bacteria gives acetic and lactic acid. This has an osmotic effect

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23
Q

Name an osmotic laxative

A

Lactulose

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24
Q

What are the indications for osmotic laxatives?

A

 Constipation

 Lactulose - Liver failure (reduced production of ammonia)

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25
Q

What is the main contraindication for osmotic laxative?

A

Intestinal obstruction

26
Q

Give four adverse drug reactions?

A

 Flatulence
 Cramps
 Abdominal discomfort
 Caution required to prevent intestinal obstruction

27
Q

How quickly do magnesium and sodium (osmotic laxatives) work?

A

Quickly and severly, so should be reserved for resistant constipation if urgent relief is required

28
Q

What is the mechanism of action of irritant laxatives?

A

 Increase gastrointestinal peristalsis and water and electrolyte secretion by the mucosa. Possibly by excitation of sensory enteric nerves.

29
Q

What are the indications for osmotic laxatives?

A

 Constipation and bowel evacuation prior to medical/surgical procedures

30
Q

What are the contraindications for osmotic laxatives?

A

Intestinal obstruction

31
Q

What are two ADRs to stimulant laxatives?

A

Atony

Hypokalaemia

32
Q

How can stimulant laxative abuse be detected?

A

Melanosis coli (pigmentation of the bowel wall)

33
Q

What is diarrhoe?

A

The passage of frequent, liquid stools

34
Q

What are some causes of diarrhoea?

A

Infections, toxins, drugs, chronic disease and anxiety

35
Q

Name an anti-motility anti-diarrhoeal

A

Imodium

Codeine

36
Q

Give a contraindication for an anti-motilitity anti-diarrhoeal

A

Inflammatory Bowel Disease - Toxic Megacolon

37
Q

What is the mechanism of action of anti-motility anti-diarrhoeals

A

 Act on opioid receptors in the bowel
 Reduce motility (increase time for fluid reabsorption)
 Increase anal tone and reduce sensory defecation reflex

38
Q

Give some ADRs of anti-motility anti-diarrhoeals

A

 Nausea, vomiting, abdominal cramps, constipation drowsiness

39
Q

What is spesh about imodium?

A

40 times more potent than Morphine as an antidiarrhoeal agent, and penetrates the CNS poorly

40
Q

What are bulk forming anti-diarroeals used for?

A

IBS and ileostomy

41
Q

What are some contraindications for bulk forming antidiarrhoeals?

A

Intestinal obstructions

42
Q

What is a mechanism of action fo bulk forming anti-diarrhoeals

A

A relatively small amount of faecal fluid (10-20ml) influences composition. Bulk forming antidiarrhoeals absorb this fluid

43
Q

What are four symptoms of IBS?

A

o Abdominal Pain
o Discomfort
o Bloating
o Alteration of Bowel Habits

44
Q

What is used to treat IBS?

A

Mebeverine which has a direct decreasing effect on colonic hypermotility

45
Q

Outline the process of vomiting

A

o Pyloric sphincter closes while the cardia and oesophagus relax
o Gastric contents propelled by contraction of abdominal wall and diaphragm
o Glottis closes with elevation of soft palate, preventing entry of vomit into the trachea and Nasopharynx
 If vomiting is due to alcohol, or patient has a cranial nerve lesion they are at a higher risk of aspiration as this does not work properly

46
Q

Name four stimulating factors for vomiting

A

Meds, toxins, pain

  • Smell, touch
  • Raised ICP
  • Stretching of the stomach
47
Q

What does external stimulation act on to stimulate vomiting?

A

Postrema (floor of 4th ventricle) which acts on medullary centre -> Medullary centre releases Ach, histamine and serotonin which causes emesis

48
Q

How does spinning round and round cause vomiting?

A

Causes dysfunction of vestibular apparatus, which released Ach + Histamine -> Medullar centre, Ach, histamine, serotonin -> Emesis

49
Q

Give four ways you can prevent vomiting

A

Dopamine antagonists
Serotonin antagonists
Anti-muscarinincs
Histamine receptor antagonists

50
Q

What are two key indications for dopamine receptor antagonists?

A

 Acute nausea/vomiting

 Especially induced by L-DOPA or dopamine agonists

51
Q

What is the mech of action for dopamine antagonists?

A

 Acts on the Postrema on the floor of the 4th ventricle

 Acts on the stomach to increase the rate of gastric emptying

52
Q

What are two key ADRs for dopamine receptor antagonists?

A

 Stimulates prolactin release

 Metoclopramide – extra-pyramidal reactions (dystonia) occur in 1%, therefore is avoided in Parkinson’s disease

53
Q

What is the main indication for serotonin antagonists?

A

 In high doses in radiation sickness, chemotherapy sickness, post operatively

54
Q

What is the main mechanisms of action for serotonin antagonists?

A

 5-HT is released into the gut, reducing Vagus activity, therefore effective at deactivating the vomiting centre (the Postrema on the floor of the 4th ventricle)
 Blocks Serotonin receptors in Chemoreceptor Trigger Zone

55
Q

What are three ADRs of serotonin antagonists?

A

Headaches, constipation, flushing

56
Q

How can serotonin antagonist effects be amplified?

A

Dose of corticosteroid

57
Q

What are anti-muscarinincs used for?

A

Motion sickness

58
Q

What some ADRs of anti-muscarinics?

A

Systemic anti-cholinergic effects, bradycardia

59
Q

What are histamine receptor antagonists used for?

A

Acute nausea and vomiting

60
Q

What is a contraindication for histamine antagonists

A

Myocardial ischaemia

61
Q

What are two ADR of histamine receptor antagonists?

A

Can cause QT prolongation

Crosses the BBB - Sedative effect

62
Q

Give two other drugs with anti-emetic effects?

A

Cannaboids

Benzodiazepines

Semester 5 - Farmocology (27 decks)

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