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Flashcards in Gastic Pharmacology Deck (18):
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Gastro-oesophageal reflux disease

Leads too oesophagitis
Risk increased by:
Obesity
Pregnancy
Drugs
Burning pain that gets worse on bending down
Causes:
Weak sphincter
Relaxation of sphincter by drugs
Increased intra abdo pressure

1

Peptic ulceration signs and symptoms

Epigastic pain-> variable in relation to food
Hunger pain which is relieved by eating
Night pain which is relived by food
Water brash
Nausea
Haematemesis

2

Peptic ulceration causes

Caused by helicobacter pylori infection in 70% of cases
Remainder mostly NSAID induced
May lead to chronic inflammation and gastric damage

3

Test for H pylori

Urea breath test
Drink C13
C13 urea is broken down by urease (H.pylori) to produce NH3 and CO2
Biopsy for urease activity
H pylori antigens/antibodies in the blood

4

Warning signs for poetic ulceration

Aged 55 and over
Weight loss
Anaemia
Dysphagia
Haematemesis
Melaena
Upper abdominal masses
Persistant symptoms
Onset of new symptoms

5

Control of acid secretion

Increased:
Gastrin
Histamine
Acetylcholine
Decreased:
Prostaglandins
Bicarbonate and mucous release

6

Goals of treatment

Symptomatic relief or cure
Life style changes:
Avoidance of causative drugs
Avoidance of causative factors
GORD propping up bed, removing belts
Suppression of acid release
Mucosal protection
Cure may involve suppression of acid release to allow natural healing and irradiation of H pylori

7

Antacids

OTC
raise pH
Sodium bicarbonate, magnesium hydroxide, aluminium-> buffer H

8

Aliginates

Aliginic acid combines with saliva to form a viscous foam which floats on the gastric contents-> protects oesophagus during reflux

9

H2 receptor antagonists

Antagonise histamine
Cimetidine, ranitidine (2 weeks OTC) famotidine
Low does short term OTC, referred if over 45
Decrease proton pump action-> decrease cAMP-> decrease acid production
Symptomatic relief-> haven't removed cause
Reduce he need for surgery
Take at night

10

Cimetidine

Inhibits cytochrome p450 and therefore the metabolism of other drugs-> important drug interactions
Oral anticoagulants
Carbamezepine
Tricyclics antidepressants

11

Proton pump inhibitors

Omeprazole (low does OTC),pentoprazole, lensoprazole
Irreversible inhibition of the proton pump-> H/K ATPase
Activated by acid
Inhibit H secretion by more than 90%-> achlorhydria
Increased risk of infection

12

Prokinetic drugs

Cause gastric emptying
Used for GORD
Domeperidine-> increased closer of oesophageal sphincter->opens lower sphincter
Metocloperamide-> locally increase gastric motility

13

Helicobacter pylori eradication

Most effective treatment for long term cure
2 antibiotics:
Metronidazole
Amoxicillin
Clarithromycin
PPI or H2 antagonist
Sometimes bismuth chelate-> kills Hpylori,coats ulcer, absorbs pepsin, increases prostaglandin production, increases HCO3 secretion

14

Non H pylori dyspepsia

Stepping approach
1 Antacid or Aliginates+antacid
2 H2 antagonists
3 PPI

15

Ulcerogenic effects of NSAIDS

Inhibit the arachidonic acid pathway
Steroids-> lipocortin-> inhibit PLA2 so arachidonic acid can't be produced
NSAIDS-> inhibit COX-> arachidonic acid can't be converted to prostaglandins (protective)

16

Cyclooxygenesis-> COX

Exists as two isoforms
COX-1-> physiological->gastric protection
COX-2->pathological-> inflammation
Most NSAIDS inhibit both
COX-2 selective-> less GI side effects celecoxb

17

Minimising GI damage

Prophylaxis with PPI
H2 antagonists less or ineffective
Give in combination with misoprostol-> stable PGE analogue-> acts on prostanoid receptors to inhibit gastric H secretion
Take with food