Gastrointestinal Drugs

Question 1

Drug interactions with gaviscon?

Answer 1

may reduce serum concentrations e.g. ACEi, bisphosphonates, PPIs so ideally take at different times.

Question 2

Ranitidine > what class of drug? When used? Excreted via..?

Answer 2

H2-receptor antagonists reduce gastric acid secretion

Use: peptic ulcer disease (to treat and prevent, although PPIs usually used) and GORD & dyspepsia to relieve symptoms

SEs: few, bowel disturbance (diarrhoea/constipation), headache, dizziness

Excreted by kidneys (renal impairment), disguise symptoms of gastric cancer (like PPIs)

Question 3

Omeprazole, Lansoprazole, uses? Interactions? Warning?

Answer 3

First line treatment for: peptic ulcer disease including NSAID-associated ulcers, symptomatic relief of dyspepsia/GORD and eradication of H.pylori (+2 Ab’s)

Warning: may disguise symptoms of gastric cancer, may increase fracture risk in patients w/ osteoporosis.
Interactions: omeprazole may reduce antiplatelet effect of clopidogrel (via CYT P450)

Question 4

Loperamide?

Works how?

Answer 4

As a symptomatic treatment of diarrhoea (IBS, gastroenteritis)

An opioid but does not penetrate CNS so no analgesic effect, an agonist of opioid μ-receptors in the GI tract decreasing contractions so transit of bowel contents is slowed and anal sphincter tone increased

Question 5

Name one stimulant laxative and one osmotic?

Answer 5

Stimulant - senna

Osmotic - Lactulose

Question 6

Mesalazine used to treat..?

Answer 6

first line for mild-moderate UC

Mechanism: release 5-aminosalicyclic acid (5-ASA) which has anti-inflammatory and immunosuppressive effects

Question 7

Metoclopramide.. ?

Works how?

Avoid in who?

Answer 7

Anti-emetic

Mechanism: Dopamine D2 receptor antagonists, D2 is the main R in the chemoreceptor trigger zone (vomiting centre), drugs that block these receptors have a prokinetic effect, promoting gastric emptying
SEs: Diarrhoea, extrapyramidal symptoms (movement abnormalities) via same mechanism as anti-psychotics (avoid in children and young adults). Can also cause acute dystonic reaction.
Avoid in GI obstruction and perforation
Interaction: extrapyramidal SEs risk increased w/ antipsychotics. Will antagonise (oppose) dopaminergic agents for PD