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HHD and Pharmacology from Anki > inhibitors of gastric acid secretion > Flashcards

inhibitors of gastric acid secretion Flashcards

1
Q

Antacids are more effective on which kinds of ulcers?

A

Duodenal ulcers
less effective on gastric ulcers

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2
Q

Antacids contain

A

salts of magnesium - magnesiym hydroxide, magnesiym trisilicate
salts of aluminium- aluminium hydroxide gel
combined with alginates and simeticone

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3
Q

At what stage of development is H. pylori often acquired?

A

During childhood

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4
Q

Bismuth subsalicylate has minimal GI absorption. True or false

A

True

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5
Q

Briefly state the MOA for Misoprostol ;

A

reduce gastric acid secretion
increase mucosal blood flow
secretion of mucous and bicarbonate

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6
Q

Chief cells produce…

A

Pepsin- breaks down proteins
Lipase- breaks down fats

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7
Q

Cimetidine may cause gynaecomastia in men due to …

A

low affinity for androgen receptors
((prevents testoterone from having its effects?)

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8
Q

D cells in the stomach secrete

A

Somatostatin; inhibits the release of other hormones from cells in the stomach lining

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9
Q

Excess salts of aluminium can cause _____

A

constipation

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10
Q

Excess salts of magnesium can cause ___

A

diarrhoea

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11
Q

Generally, how can we prevent peptic ulcers

A

lifestle measures
avoid gastric irritants
boost gastric defences
reduce gastric acid secretion

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12
Q

Give examples of cytoprotective drugs

A

Sucralfate: complex of aluminium hydroxide and sulphated sucrose, releases the aluminium in the presence of acid
Bismuth subsalicylate
Misoprostol

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13
Q

Give exampls of proton pump inhibitors

A

lansoprazole
omeprazole
esomeprazole

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14
Q

H pylori infection is implicated in what instances?

A

causative factor in gastric acid production
peptic ulcers
gastric ulcers

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15
Q

H. pylori is a gram _____ bacteria found in ____ UK population

A

negative
10-15%

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16
Q

H. pylori is found in ___ of patients with duodenal cancer

A

80%

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17
Q

H2 receptor antagonists are eliminated by the ____

A

Kidneys

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18
Q

How are PPIs adminisitered

A

most commonly orally
omeprazole contains enteric coated granules as degraded quickly at low pH

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19
Q

How do antacids work?

A

They work by directly neutralising the gastric acid

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20
Q

How do ulcers develop?

A

failure of luminal defences- decrease mucous and HCO3, < protection of mucosa against acidic lumen
failure to inhibity gastric acid secretion; build up of acid damages unprotected mucosa
increased pepsin secretion; proteins break down in unprotected mucosa
increase gastric emptying into duodenum; increased acid reached duodenum causing ulcers
h. pylori infection

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21
Q

Infection of H. pylori can lead to the following conditions:

A

Gastritis
Peptic ulcers
Gastric cancers
MALToma

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22
Q

List some H2 receptor antagonists

A

cimetidine
ranitidine
famotidine

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23
Q

Misoprostol limits gastric mucosa damage by NSAIDs and promote ulcer healing. True or false

A

True

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24
Q

Mucous cells of the stomach produce…

A

Mucus (protective layer)
Bicarbonate (mucosal surface pH 6-7; protect mucosal cells from acidic lumen of pH 1-2)

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25
Q

Non ulcer dyspepsia (NUD) or functional dyspeptis is characterised by …

A

no cause found for symptoms
no ulcer
increased GI sensitivity to distension
Increased GI sensitivity to gastric acid

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26
Q

Parietal cells produce…

A

HCl which is important in proteolytic digestion of food, iron absorption and killing pathogens

27
Q

Peptic ulcer disease is characterised by…

A

peptic ulcer (break in the lining of stomach, duodenum or lower oesophagus)
ulcer in stomach (gastric ulcer)
ulcer in duodenum (duodenal ulcer)
epigastric pain in upper abdominal region

28
Q

Pharmacologically how can we treat gastric ulcers?

A

proton pump inhibitors
histamine H2 receptor antagonists (act on parietal cells in stomach which release HCl)
antacids
cytoprotective drugs
antibiotics

29
Q

PPIs are eliminated by the ___

A

Liver

30
Q

Reinfection of the h.pylori organism is not possible after elimination. True or false

A

False
Hence screening is important

31
Q

The eradication of H pylori infection has what effect on ulcers?

A

promotes rapid and long term healing of ulcers

32
Q

What aggravates a gastric ulcer and what does this lead to

A

GU is worse with eating and this leads to weight loss

33
Q

What alleviates a duodenal ulcer and briefly explain why

A

DU is better with eating due to the action of the acid on food

34
Q

What ar the 3 regulatory molceules that stimulate acid secretion

A

Acetylcholine- M3AChR- parietal cell
Histamine- H2R on parietal cells
gastrin- released from G cell which act on CCK (cholecytokinin) receptors on ECL (enterochromaffin like cells) which cause the release of histamine (which stimulate HCl)

35
Q

What are cytoprotective drugs

A

drugs which protect the mucosa by
enhancing endogenous mucosal protection
provide a physical barried the surface fo the ulcer

36
Q

What are the adverse effects of bismuth subsalicylate

A

blackening of tongue and faeces
nausea and vomiting
raised plasma levels during renal impairment can cause encephalopathy

37
Q

What are the adverse effects of H2 receptor antagonists

A

diarrhoea
dizziness
muscle pain
headache
transient rash
cimetidine inhibits cytochrome P450 reducing metabolism (this potentiating the action) of other drugs, anticoagulants and tricyclic antidepressants

38
Q

What are the adverse effects of misoprostol

A

diarrhoea
abdominal cramos
avoid in pregnancy due to induction of uterine contraciton leading to abortion

39
Q

What are the adverse effects of PPIs

A

diarrhoea
dizziness
muscle pain
headache
rash
nausea
low Na+
Inhibits enzyme CYP2C19 which is required by clopidogrel to produce the active metabolite (decreasing antiplatelet effect)
caution in people with liver disease

40
Q

What are the adverse effects of sucralfate

A

given orally, poor GI absorption; in an acid environment it produces a paste which can become an obstructive lump (Bezoar), leading to constipation
reduces absorption of fluoroquinoine antibiotics, theophylline, tetracycline, digoxin, amitriptyline

41
Q

What are the adverse side effects of antacids?

A

constipation
flatulence
systemic alkalosis
metabolic bone disease (aluminium)
drug interactions- bind to and reduce the effects of tetracycline (antibiotic)

42
Q

What are the complacations of peptic ulcers

A

slow or fast bleeding- leads to anaemia
perforating (in stomach wall)
peritonitis (inflammation of the peritoneum)
septicaemia (blood poisoning and infection)
scarring- gastri outlet obstruction
death

43
Q

What are the cytoprotective effects of prostaglandincs PGE2 and PGI2?

A

decrease gastric secretion
increase gastric mucous secretion
increase HCO3 secretion
prevent vasoconstricion, thus prevent damage to the mucosa following injury (encourage blood flow)

44
Q

What are the protective mechaninsm in place in the stomach used to prevent gastric mucosal injury?

A

Mucous layer with HCO3; protects the mucosal cells from acidic lumen (pH 1-2)
Prostaglandins (local hormones)- produced by most cells in GI tract
Cell renewal; every 4-6 days, replace damaged cells
Tight cell junctions- prevent acid from seeping into deeper layers

45
Q

What are the risk factors for peptic ulcers

A

smoking
excess alcohol
NSAIDs
physoological stresses
gender: DU more common than GU in females

46
Q

What is an indication for misopriostol

A

deficiency in endogenous prostaglandin when NSAIDs may cause ulcer formation

47
Q

What is dyspepsia

A

a condition characterised by upper abdomina symptoms that include pain or discomfort, bloating, feeling of fullness with very little intake of food, feeling of unusual fulless following meals, nausea and vomiting, loss of appetite, heartburn, regurgitation of food or acid and belching

48
Q

What is gynaecomastia?

A

increase in the amount of breast gland tissue in men/boys

49
Q

What is misoprostol

A

prostaglandin analogue (PGE1 and PGI2)

50
Q

What is the function of alginates in antacids

A

increase viscocity and adherence of mucous to oesophagus (protective barrier during reflux)

51
Q

What is the function of simeticone in antacids

A

antifoaming agentm relieves bloating and flatulence

52
Q

What is the half-life of PPIs

A

1 hour but a single dose can affect secretion for 2-3 days as it irreversibly blocks the proton pump

53
Q

What is the mechanism of action of H.pylori

A

penetrates the mucous lining
produces an enzyme called urease
urease catalyses the hydrolysis of urea into carbondioxide and ammonia
ammonia is toxic to mucosal epithelial cells and neutralises pH at mucosa, allowing survival of bacteria

54
Q

What is the mechanism of action of H2 receptor antagonists

A

inhibits H2 receptors on parietal cells
inhibit histamine and gastrin stimulated acid secretion (and pepsin release)
promote healing of gastric ulcers

55
Q

What is the mechanism of action of proton pump inhibitors

A

inhibits K+, H+ ATPase proton pump on parietal cells which reduces acid secretion

56
Q

What is the mechanism of action of sucralfate

A

the residual anionic complex binds to cationic glycoproteins/proteins in mucous and decreased their degradtion by pepsin
stimulates secretion of mucous, bicarbonate, and prostaglandins from gastric mucoisa (increasing the protective layer)

57
Q

What is the MOA of bismuth subsalicylate

A

precipitates in acidic pH and binds to the ulcer base
when used in combination H. pylorin regimens, it has a toxic effect on the bacillus by inhibiting bacterial adherence to the mucosal
inhibit the bacterial enzymes

58
Q

What is the one regulatory molecule that inhibits acid secretion?

A

Somatostatin
Released from D cells and acts on G cells, ECL cells and parietal cells to inhibit gastrin, histamine and HCl secretion respectively

59
Q

What leads to the pathogenesis often observed in gastric mucosal injurt

A

Disturbance in protective mechanisms and excessive gastric secretions

60
Q

What method of administration is available for H2 receptor antagonists

A

orally (well absorbed by GI tract)
IM and IV preparations available
low dose over the counter available

61
Q

What type of drugs provide th simplest way to treat symptoms of excessive gastic acid secretion, provide quick relief and have a prolonged effect after food?

A

antacids

62
Q

Why are NSAIDs like aspirin a risk factor for peptic ulcers

A

they are acidic molecules which directly irritate gastric mucosa
inhibition of COX-1 and 2 which reduces the levels of protective prostaglandins

63
Q

With a positive h. pylori test, the organism can be eradicated in 2 weeks using what kind or therapy

A

triple therapy:
PPI ( decrease gastric acid secretion)
anti-bacterials (amoxicillin, clarithomycin/metronidazole)
bismuth subsalicylate (cytoprotective drug- prevent adhesion to mucosa and inhibits the bacterial enzymes

HHD and Pharmacology from Anki (1 decks)

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