Gastro pharmacology Flashcards
Aminosalicylate drugs
treatment of what disease
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
Sulphasalazine side effects
a combination of sulphapyridine (a sulphonamide) and 5-ASA
rashes oligospermia headache Heinz body anaemia megaloblastic anaemia lung fibrosis
Mesalazine
a delayed release form of 5-ASA
pancreatitis is more common mesalazine and sulphasalazine
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
Metoclopramide
MOA used in management of what
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.
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
Metoclopramide
side effects of metoclopramide
extrapyramidal effects: oculogyric crisis. This is particularly a problem in children and young adults
hyperprolactinaemia
tardive dyskinesia
parkinsonism
When should metoclopramide be avoided
Metoclopramide should be avoided in bowel obstruction, but may be helpful in paralytic ileus.
Megaloblastic anaemia is an adverse effect of what drug
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
omeprazole is a PPI what is its MOA
Proton pump inhibitors (PPI) cause irreversible blockade of H+/K+ ATPase of the gastric parietal cell.
side effects of omeprazole
hyponatraemia, hypomagnasaemia
osteoporosis → increased risk of fractures
microscopic colitis
increased risk of Clostridium difficile infections
what drug MoA is to act on μ-opioid receptors in the myenteric plexus of the large intestine and in antidioarrhoel
loperamide
4 types of laxatives
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
heparin can cause what at low doses
Heparin causes hyperkalemia by
inhibiting aldosterone synthesis even at lower doses
what stimulant laxative should only be prescribed to palliative patients due to carcinogenic potential
co-danthramer should only be prescribed to palliative patients due to its carcinogenic potential
Which of the following antiemetics promotes gastric emptying?
metoclopramide
what drug is first line for Wilsons disease
pencillamine
Cholestyramine treats what
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.
side effects of cholestyramine
abdominal cramps and constipation
decreases absorption of fat-soluble vitamins
cholesterol gallstones
may raise level of triglycerides
Diphenoxylate does what
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
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?
blocks dopamine receptors on CTZ and acts on 5-HT receptors
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?
Metoclopramide should be avoided in children and young adults due to the risk of developing oculogyric crisis.
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?
metoclopramide
Clopidogrel
anitplatelt actions
when is GTN used
Glyceryl trinitrate (GTN) is used in angina, GTN causes vasodilation relieving the symptoms of chest pain in angina.
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?
Sulphasalazine can cause oligospermia and infertility in men
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?
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.
oculogyric crisis characterised by
upward gaze of the eyes
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?
ranitidine
off market now
H2 receptor antagonist second to PPIs
