Gastro Flashcards
What are the common uses of spironolactone?
to treat ascites and oedema due to liver cirrhosis
to treat chronic heart failure
to treat primary hyperaldosteronism
What is the mechanism of action of spironolactone?
Aldosterone antagonist
- increases sodium and water excretion and increases potassium retention by acting on distal tubules
What are important adverse reactions of spironolactone?
hyperkalaemia
gynaecomastia
liver impairment
jaundice
What are the warning for spironolactone?
renal impairment, hyperkalaemia, Addison’s disease, pregnant or lactating
What are important interactions for spironolactone?
any K+ elevating drugs - ACE-i, ARBs, potassium supplements
What are indications for giving azathioprine?
to maintain remission in IBD
disease modifying drug in autoimmune e.g. RA
to prevent organ rejection
What is the mechanism of action of azathioprine?
stops DNA and RNA replication in lymphocytes
What are some warnings of azathioprine?
should not be prescribed in absent TPMT activity
caution in liver or renal impairment, pregnancy
caution in previous hypersensitivity reaction
What are some interactions of azathioprine?
+corticosteroids = increased risk of infection
not prescribed with xanthine oxidase inhibitors e.g. allopurinol
trimethoprim increases chance of leukopenia
azathioprine can reduce effect of warfarin
What are examples and indications of alginates and antacids?
gaviscon or peptac
GORD, dyspepsia
What is the mechanism of alignates and antacids?
antacids - buffer stomach acids
alignates - increase viscosity of stomach contents, which reduces reflux
What are some adverse reactions of alignates and antacids?
GI upset
What are some cautions of alignates and antacids?
in children, do not give with thickened foods
caution with renal failure
can worsen hypoglycaemia
What are some interactions with alignates and antacids?
can bind to other drugs and reduce absorption so give drugs 2 hours after (esp. antibiotics, ACE-i, bisphosphonates)
can increase excretion of aspirin and lithium
What are names of aminosalicylates and how do they work?
mesalazine, sulfasalazine
they have antiinflammatory and immunosuppressive effects
What are the indications of aminosalicylates?
UC and RA
What are adverse effects of aminosalicylates?
GI upset, headache, renal impairment, oligospermia, hypersensitivity
What are warnings of aminosalicylates?
aspirin hypersensitivity - mesalazine and sulfasalazine are salicylates, like aspirin
What are important interactions of aminosalicylates?
mesalazine is pH coated so things that effect pH interact - PPIs, lactulose
What are the 3 groups of antiemetics?
Histamine antagonists - cyclizine
Serotonin antagonists - ondansteron
dopamine (D2) antagonist - domperidone, metoclopramide
DON’T USE METOCLOPRAMIDE IN PD
What are domperidone and metoclopramide used for and how do they work?
To reduce nausea and vomiting (antiemetic) especially in context of reduced gut mobility
D2 receptor antagonists
What are some SE of domperidone and metoclopramide?
diarrhoea
metoclopramide - extrapyramidal symptoms - do not give in PD
What are some warnings for D2 antagonist antiemetics?
Don’t give in young people, people at risk of cardiac problems (it prolongs QT interval)
don’t give metoclopramide in PD as it crosses blood-brain barrier
What is cyclizine and how does it work?
antiemetic - especially in context of vertigo
histamine receptor antagonist
What are some SE of cyclizine?
dry mouth
tachycardia
drowsiness
What are some warnings of cyclizine?
don’t give with hepatic encephalopathy
don’t give with other sedative drugs
don’t give in prostatic hyperplasia
Give some examples of anti-motility drugs, what they are used for and how they work?
loperamide and codeine phosphate
to treat diarrhoea
both act on u-receptors - loperamide only in gut so no analgesia (preferable)
What are some adverse effects of anti-motility drugs?
type A (augmented) effects - GI problems e.g. constipation, cramps, flatulence
What are some warnings and interactions with anti-motility drugs?
don’t give loperamide if UC, C. diff or bloody diarrhoea
Don’t give codeine unless analgesic effect is required
What is the common H2-receptor antagonist, what is it used for and how does it work?
ranitidine
peptic ulcer disease, GORD, dyspepsia
it reduces gastric acid secretion
What are adverse reactions of ranitidine?
very few SE
bowel disturbance, headache, dizziness
What are some warnings and interactions of ranitidine?
excreted by kidneys so reduce dose in renal impairment
can disguise symptoms of gastro-oesophageal cancer
no significant interactions
What are some examples of osmotic laxatives, what are they used for and how do they work?
lactulose, macrogel, phosphate enema
used for constipation, faecal impaction, bowel preparation, hepatic encephalopathy
they are osmotically active substances so hold water in stool, keeping volume and stimulating peristalsis.
Lactulose reduces ammonia absorption so good for liver failure which has led to hepatic encephalopathy
What are some adverse effects of osmotic laxatives?
flactulance, abdo cramps, nausea, diarrhoea
phosphate enema - local irriation, electrolyte disturbances
What are some cautions and important interactions of osmotic laxatives?
intestinal obstruction as risk of perforation
phosphate enemas - fluid shifts so shouldn’t be sued in heart failure, ascites, electrolyte disturbances
no significant interactions but effect of warfarin could be increased
What are some examples of stimulant laxatives, what are they used for and how do they work?
senna, bisacodyl, glycerol suppositories, docusate sodium
used for constipation, suppositories can be used for faecal impaction
encourage water and electrolyte secretion from colonic mucosa so increase volume of colonic content and stimulate peristalsis
What are some adverse effects of stimulating laxatives?
abdominal pain, cramping, diarrhoea
What are some cautions and interactions of stimulating laxatives?
don’t give when intestinal obstruction as can induce perforation, avoid suppositories in haemorrhoids and anal fissures
no interactions
