GI Drugs Flashcards

1
Q

Antacids example

A

Gaviscon

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2
Q

Antacids MOA

A
  • Compound containing alginate and 1+ antacid
  • Alginate: increase viscosity of stomach contents to reduce reflux
  • Antacids: buffer stomach acids
  • After reacting with stomach contents, form a floating ‘raft’ which separates gastric contents from GOJ preventing mucosal damage
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3
Q

Antacids indications

A
  1. Ulcers
  2. Non-ulcer dyspepsia
  3. GORD
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4
Q

Antacids contraindications

A
  • Aluminium / magnesium hydroxide should not be given to patients with hypophosphatemia
  • Sodium bicarbonate avoided for patients on low salt diet
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5
Q

Antacids side effects

A
  • constipation / diarrhoea
  • flatulence
  • stomach cramps
  • nausea
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6
Q

Antacids interactions

A

Divalent cations in compound alginates bind to other drugs and reduce their absorption: ACEi, Abx, bisphosphonates, digoxin, levothyroxine, PPIs.
Doses should be taken at different times - 2 hour gap

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7
Q

Antacids patient info

A

Action prolonged if durg taken 1-3 hours after food

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8
Q

H2 receptor agonists examples

A

Ranitidine

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9
Q

H2 receptor agonists indications

A
  1. Peptic ulcer disease: treatment and prevention, although PPIs more effective
  2. GORD / dyspepsia: symptomatic relief
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10
Q

H2 receptor agonists MOA

A

Histamine from parietal cells binds to H2 receptor
Activates proton pump on parietal cell which secretes H+ into lumen (and draws K+ into cell)
Blockade of H2 = decreased acid

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11
Q

H2 receptor agonists contraindications

A

Dose reduction in renal impairment

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12
Q

H2 receptor agonists side effects

A
  • Generally well tolerated

- Most common: bowel disturbance, headache, dizziness

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13
Q

PPIs examples

A

Lansoprazole, Omeprazole Patoprazole

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14
Q

PPIs indications

A
  1. Prevention and treatment of peptic ulcer disease including NSAID-associated ulcers
  2. Symptomatic relief of dyspepsia and GORD
  3. Eradication of H. Pylori in combination with antibiotics
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15
Q

PPIs MOA

A
  • Irreversibly inhibit H+/K+ ATPase in gastric parietal cells.
  • This reduces gastric acid secretion
  • More effective than H2 receptor agonists
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16
Q

PPIs administration

A

Oral

Injectable

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17
Q

PPIs contraindications

A

-Risk of osteoporosis: can increase fracture risk

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18
Q

PPIs side effects

A
  • GI upset
  • Headache
  • Reduce host defence against infection - increased risk of C. diff
  • Prolonged treatment can cause hypomagnesia - can lead to ventricular arrhythmias
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19
Q

PPIs interactions

A

cP450 inhibitor

Reduce anti-platelet effect of clopidogrel by decreasing its activation by cP450

20
Q

PPIs patient info

A
  • Take with food or on empty stomach

- Best taken in morning

21
Q

Anti-motility agents examples

A

Loperamide, codeine phosphate

22
Q

Anti-motility agents indications

A
  1. Diarrhoea: symptomatic treatment - IBS or viral gastroenteritis
23
Q

Anti-motility agents MOA

A
  • Opioid which doesn’t penetrate the CNS so has no analgesic effects
  • Agonist of the mu-opioid receptors in the GIT, which increases non-propulsive contractions of the gut smooth muscle
  • Reduces peristaltic contractions
  • Bowel content slowed . + sphincter tone increased
  • Slower gut transit allows more time for water absorption which hardens stool
24
Q

Anti-motility agents administration

A

Oral capsule, tablet, syrup

25
Q

Anti-motility agents contraindications

A
  1. Acute ulcerative colitis: inhibition of peristalsis may increase of megacolon and perforation
  2. Clostridium difficile colitis: inc. diarrhoea associated with broad-spec antibiotic use
  3. Acute bloody diarrhoea: this may signify bacterial infection
26
Q

Anti-motility agents side effects

A
  • Constipation
  • Abdominal cramping
  • Flatulence
27
Q

Laxatives examples

A

Senna, lactulose, macrogol

28
Q

Laxatives indications

A
  1. Constipation and faecal impaction
  2. Bowel preparation prior to surgery
  3. Hepatic encephalopathy
29
Q

Laxatives MOA

A
  • Based on osmotically active substances are not digested / absorbed are left in lumen, and therefore hold water in the stool, maintaining its volume and stimulating peristalsis
  • Lactulose increases gut transit rate and acidifies the stool which inhibits ammonia producing bacteria
30
Q

Laxatives administration

A

Oral

Enema

31
Q

Laxatives contraindications

A
  1. Intestinal obstruction: risk of perforation

2. Heart failure, ascites, electrolyte disturbance: enemas can cause significant fluid shift

32
Q

Laxatives side effects

A
  • Flatulence, nausea and abdominal cramps
  • Diarrhoea
  • Phosphate enemas can cause local irritation and electrolyte disturbance
33
Q

Laxatives interactions

A

May enhance effects of warfarin

34
Q

Aminosalicylates examples

A

Mesalazine, sulfasalazine

35
Q

Aminosalicylates indications

A
  1. Ulcerative colitis: mesalazine 1st line

2. Rheumatoid arthritis: sulfasalazine acts as DMARD as part of combination therapy

36
Q

Aminosalicylates MOA

A

Ulcerative colitis: Release 5-aminosalicylic acid, which is anti-inflammatory and immunosuppressive.

37
Q

Aminosalicylates administration

A

Oral: coated in acid resistant substance so released further along gut
Foam enema
Suppository

38
Q

Aminosalicylates contraindications

A

Aspirin hypersensitivity (aspirin is salicylate)

39
Q

Aminosalicylates side effects

A

GI upset (nausea, dyspepsia)
Headache
Rare but serious blood abnormalities: leucopenia, thrombocytopenia
Renal impairment
Oligospermia
Hypersensitivity: rash, fever, liver damage

40
Q

Aminosalicylates interactions

A

Drugs which alter gut pH e.g. PPIs - may cause premature breakdown

41
Q

Anti-emetics examples

A

Metoclopramide, Domperidone

42
Q

Anti-emetics indiactions

A

Prophylaxis and treatment of nausea and vomiting, particularly in context of reduced gut motility

43
Q

Anti-emetics MOA

A
  • D2-receptor antagonists
  • D2 is main receptor in chemoreceptor trigger one of medulla, the area responsible for sensing emetogenic substances in blood e.g. drugs
  • Dopamine is important NET in gut: promotes relaxation of stomach and lower oesophageal sphincter, inhibits gastroduodenal coordination
  • D2 receptor agonists have prokinetic effect - promote gastric emptying
  • Effective in nausea and vomiting due to chemoreceptor trigger zone stimulation and reduced gut motility
44
Q

Anti-emetics adinistration

A

IV injections

45
Q

Anti-emetics contraindications

A
  1. GI obstruction

2. Young - increased risk of extra-pyramidal side effects

46
Q

Anti-emetics side effects:

A
  • Diarrhoea

- Extra-pyramidal ssyndromes: dystonic reaction

47
Q

Anti-emetics interactions

A
  1. Antipsychotics: increased risk of extra-pyramidal side effects
  2. Parkinson’s dopaminergic agents: antagonises