Gastic Pharmacology

Question 0

Peptic ulceration signs and symptoms

Answer 0

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

Question 1

Gastro-oesophageal reflux disease

Answer 1

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

Question 2

Peptic ulceration causes

Answer 2

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

Question 3

Test for H pylori

Answer 3

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

Question 4

Warning signs for poetic ulceration

Answer 4

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

Question 5

Control of acid secretion

Answer 5

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

Question 6

Goals of treatment

Answer 6

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

Question 7

Antacids

Answer 7

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

Question 8

Aliginates

Answer 8

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

Question 9

H2 receptor antagonists

Answer 9

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

Question 10

Cimetidine

Answer 10

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

Question 11

Proton pump inhibitors

Answer 11

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

Question 12

Prokinetic drugs

Answer 12

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

Question 13

Helicobacter pylori eradication

Answer 13

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

Question 14

Non H pylori dyspepsia

Answer 14

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

Question 15

Ulcerogenic effects of NSAIDS

Answer 15

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)

Question 16

Cyclooxygenesis-> COX

Answer 16

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

Question 17

Minimising GI damage

Answer 17

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