Gastro pharmacology

Question 1

Aminosalicylate drugs

treatment of what disease

Answer 1

5-aminosalicyclic acid (5-ASA) is released in the colon and is not absorbed. It acts locally as an anti-inflammatory. The mechanism of action is not fully understood but 5-ASA may inhibit prostaglandin synthesis

treat inflammation and ulcerative colitis

Question 2

Sulphasalazine side effects

a combination of sulphapyridine (a sulphonamide) and 5-ASA

Answer 2

rashes
oligospermia
headache
Heinz body anaemia
megaloblastic anaemia
lung fibrosis

Question 3

Mesalazine
a delayed release form of 5-ASA

pancreatitis is more common mesalazine and sulphasalazine

Answer 3

pancreatitis is 7 times more common in patients taking mesalazine than sulfasalazine

Olsalazine
two molecules of 5-ASA linked by a diazo bond, which is broken by colonic bacteria

Question 4

Metoclopramide

MOA used in management of what

Answer 4

D2 receptor antagonist* mainly used in the management of nausea

also has an agonist effect on peripheral 5HT3

antagonist effect on muscarinic receptors to promote gastric emptying

In intestinal obstruction, gastric emptying is not possible and this effect is undesirable.

Question 5

gastro-oesophageal reflux disease
prokinetic action is useful in gastroparesis secondary to diabetic neuropathy
often combined with analgesics for the treatment of migraine (migraine attacks result in gastroparesis, slowing the absorption of analgesics)

what other drug treats this

Answer 5

Metoclopramide

Question 6

side effects of metoclopramide

Answer 6

extrapyramidal effects: oculogyric crisis. This is particularly a problem in children and young adults
hyperprolactinaemia
tardive dyskinesia
parkinsonism

Question 7

When should metoclopramide be avoided

Answer 7

Metoclopramide should be avoided in bowel obstruction, but may be helpful in paralytic ileus.

Question 8

Megaloblastic anaemia is an adverse effect of what drug

Answer 8

sulfasalazine

past history of ulcerative colitis

Poor iron intake leads to iron deficiency which is a common cause of microcytic anaemia.

Sickle cell anaemia causes microcytic anaemia.

hypothyroidism causes macrocyclic anaemia but thyroid tests are normal

Question 9

omeprazole is a PPI what is its MOA

Answer 9

Proton pump inhibitors (PPI) cause irreversible blockade of H+/K+ ATPase of the gastric parietal cell.

Question 10

side effects of omeprazole

Answer 10

hyponatraemia, hypomagnasaemia
osteoporosis → increased risk of fractures
microscopic colitis
increased risk of Clostridium difficile infections

Question 11

what drug MoA is to act on μ-opioid receptors in the myenteric plexus of the large intestine and in antidioarrhoel

Answer 11

loperamide

Question 12

4 types of laxatives

Answer 12

The BNF divides laxatives into the following groups:
osmotic laxatives
stimulant
bulk-forming
faecal softners

Osmotic laxatives
examples include lactulose, macrogols and rectal phosphates

Stimulant laxatives
examples include senna, docusate, bisacodyl and glycerol
co-danthramer should only be prescribed to palliative patients due to its carcinogenic potential

Bulk-forming laxatives
examples include ispaghula husk and methylcellulose

Faecal softners
include arachis oil enemas
not commonly prescribed

Question 13

heparin can cause what at low doses

Answer 13

Heparin causes hyperkalemia by

inhibiting aldosterone synthesis even at lower doses

Question 14

what stimulant laxative should only be prescribed to palliative patients due to carcinogenic potential

Answer 14

co-danthramer should only be prescribed to palliative patients due to its carcinogenic potential

Question 15

Which of the following antiemetics promotes gastric emptying?

Answer 15

metoclopramide

Question 16

what drug is first line for Wilsons disease

Answer 16

pencillamine

Question 17

Cholestyramine treats what

Answer 17

hyperlipidemia

bile-acid sequestrant and affects the absorption of fat-soluble vitamins, namely; vitamin A, D, E, and K. Vitamin K is crucial for the production of factors II, VII, IX and X. Vitamin K deficiency can, therefore, lead to clotting abnormalities.

Question 18

side effects of cholestyramine

Answer 18

abdominal cramps and constipation
decreases absorption of fat-soluble vitamins
cholesterol gallstones
may raise level of triglycerides

Question 19

Diphenoxylate does what

Answer 19

Diphenoxylate acts on μ-opioid receptors in the GI tract to slow down peristalsis.

Activation of muscarinic receptors would cause a positive cholinergic effect resulting in increased gut motility.

antidiarrhoeal

Question 20

You are an FY2 on the oncology ward. A 33-year-old patient being treated for melanoma complains of vomiting. After weighing up the potential anti-emetics, your consultant asks you to start the patient on metoclopramide, as he thinks it will be effective in this case due to it’s unique mechanism of action.

What is the mechanism of action of this anti-emetic?

Answer 20

blocks dopamine receptors on CTZ and acts on 5-HT receptors

Question 21

A 16-year-old girl is admitted to hospital with severe nausea and vomiting. She has not been able to eat or drink in 48 hours and has not passed urine in 24 hours. An antiemetic is prescribed. Which antiemetic should be avoided in this case?

Answer 21

Metoclopramide should be avoided in children and young adults due to the risk of developing oculogyric crisis.

Question 22

A 78-year-old male with Parkinson’s disease (PD) presents to the emergency department following acute chest pain. You suspect a myocardial infarction. Which of the following treatments is contraindicated in the care of this patient?

Answer 22

metoclopramide

Question 23

Clopidogrel

Answer 23

anitplatelt actions

Question 24

when is GTN used

Answer 24

Glyceryl trinitrate (GTN) is used in angina, GTN causes vasodilation relieving the symptoms of chest pain in angina.

Question 25

A 24-year-old man presents to you with his partner concerned that they haven’t been able to conceive despite trying for the past 14 months. He denies problems getting aroused and maintaining erections.

He has a past medical history of depression, ulcerative colitis, recurrent sinusitis and hypertrophic cardiac myopathy. His partner has been tested and had no abnormalities detected.

His semen analysis results show a low sperm count.

Which one of the following medications may have caused this?

Answer 25

Sulphasalazine can cause oligospermia and infertility in men

Question 26

An 18-year-old girl presents to the emergency department with nausea and vomiting. She is seen by a medical trainee, who has just started her emergency attachment. She prescribes metoclopramide to help with nausea and vomiting before ordering some investigations.

The nurse reminds the doctor that metoclopramide is contraindicated in young female patients, and should be switched to cyclizine.

Why is metoclopramide contraindicated in this patient?

Answer 26

Use of metoclopramide in children and young adults is associated with the risk of oculogyric crisis - a dystonic reaction characterised by a prolonged involuntary upward gaze of the eyes.

Question 27

oculogyric crisis characterised by

Answer 27

upward gaze of the eyes

Question 28

A 57-year-old man and his wife present to their family physician. His wife has recently noticed a change in the size of his chest and feels that he might be growing breast tissue. She says his nipples look bigger and are quite obvious when he wears a fitting t-shirt. The husband doesn’t seem to be bothered. The husband has been well in himself and has a medical history of osteoarthritis of the knee, benign prostate hypertrophy, and gastroesophageal reflux disease. He can’t remember the names of his medications and has forgotten the list at home.

Which one of the following medications is likely to have caused his gynaecomastia?

Answer 28

ranitidine

off market now

H2 receptor antagonist second to PPIs