Drugs affecting the GI Tract

Question 1

What are the outcomes of GORD?

Answer 1

Oesophagitis
Stricture
BM (barretts metaplasia
OAC (oesophageal adenocarcinoma

Question 2

How is acid secretion suppressed via drugs?

Answer 2

Proton pump inhibitors (omeprazole)
H2 blockers (ranitidine)
Antacids increase pH
Alginates (Gaviscon)

Question 3

What is the active ingredient in Gaviscon?

Answer 3

Sodium alginate

Question 4

How does Gaviscon work?

Answer 4

Calcium mediated polymerisation forms a hydrogel which floats to the surface due to CO2 created by the neutralisation of the stomach acid.

Question 5

What is helicobacter pyori?

Answer 5

Gram-negative microaerophilic bacterium.
Colonises the stomach of 40% of humans.
Leads to cause of peptic ulceration and thus can cause gastritis.

Question 6

What can helicobacter pylori cause?

Answer 6

Gastritis
Gastric + Duodenal ulcers
Gastric Cancer (WHO) Class 1 carcinogen

Question 7

How does helicobacter pylori cause disease?

Answer 7

Urease produced by HP converts
Urea —> H3 + CO2+ H20 —-> NH4+ + HCO3-
HCO3- Neutralises the stomach acid

Question 8

How is helicobacter pylori treated?

Answer 8

Triple therapy of antibiotics amoxicillin, Clarithromycin and a Proton pump inhibitor

Question 9

What does Hp infection cause?

Answer 9

Hp infection in the antrum:
G-cells to hypersecrete gastrin 
Decrease antral D-cell somotastatin release
hypergastrinaemia
ultimately duodenal ulcers

Hp infection of the corpus
leads to reduced acid secretion
Hypochlorhydria.
This is largely associated with gastric ulcers

Question 10

What is Creon?

Answer 10

Enzymes that are synthetic which are packaged into enteric capsules and hence are protected from the stomach pH. This allows them to get into the small intestine where the capsule ruptures and the enzymes are released.

Question 11

What is Creon used to treat?

Answer 11

Exocrine Pancreatic Insufficiency (EPI) caused by:
Cystic fibrosis
Chronic pancreatitis where the pancreas doesn’t make enough enzymes.

Question 12

What is IBD?

Answer 12

2 forms:
Ulcerative colitis (superficial inflammation)
Chrons Disease

Question 13

What are 5-aminosalicylic acid (5-ASA)?

Answer 13

Used to treat IBD ulcerative colitis.

works by interacting with the damage epithelium to repair it by blocking production and chemotaxis of leukotrienes

Question 14

What are immunomodulators?

Answer 14

Azathioprine:
Inhibits proliferation of quickly rapidly dividing cells of the immune system and used to treat IBD by interfering with DNA synthesis

Question 15

What are biologics?

Answer 15

TNF-alpha inhibitors - an inflammatory cytokine that is involved in host defence.
Used to treat IBD
Infliximab, adalimumab, golimumab

Question 16

What are corticosteroids?

Answer 16

Bind to receptors to suppress inflammation expressed by genes or can also induce anti-imflammatory signals.

Question 17

What drugs treat IBD?

Answer 17

5-ASAs
immunomodulators
biologics
Corticosteroids

Question 18

What drugs are used to treat constipation?

Answer 18

Laxatives:
stimulant - senna, cascara

Saline (osmotic) - Mg, sulphate

Emollient (fecal softener)

Bulk forming - Bran, Methylcellulose

Question 19

Name an anti-diarrhoeal?

Answer 19

Loperamide

Question 20

How does loperamide work in preventing diarrhoea?

Answer 20

Suppresses the myenteric plexus which decreases the motility of the circular and longitudinal smooth muscles. This increases the amount of time substances stay in the intestine allowing for more water to be absorbed out of fecal matter
Also supresses the Gastrocolic reflex

Question 21

How can patients with cholera absorb nutrients?

Answer 21

Cholera toxin inhibits electroneutral Na absorption

Rely on Oral rehydration therapy where Na is absorbed through the SGLT1 transporter along with glucose.

Question 22

How is anaemia treated?

Answer 22

Treated by ferrous sulphate to remedy their Iron deficiency anaemia