Gastrointestinal System Flashcards
Give examples of antacids
Aluminium hydroxide
Magnesium carbonate
Give an example of an alginate
Sodium alginate
What is Gaviscon?
Compound preparation of an alginate and antacid
What are adverse effects of alginates and antacids?
Magnesium salts - diarrhoea
Aluminium salts - constipation
What are the warnings and contraindications for alginates and antacids?
Caution in renal failure due to sodium and potassium in the preparations
Risk of hyperglycaemia in DM due to high sucrose content
What are some DDIs of alginates and antacids?
Can reduce absorption of many drugs (so doses should be separate)
Can increase urine alkalinity which increases aspirin excretion
What is Hyoscine hydrobromide?
A muscarinic receptor antagonist that works to reduce motion sickness, as an anti-spasmodic
What are some ADRs of Hyoscine hydrobromide?
- sedation
- memory problems
- glaucoma
- dry mouth and constipation (anti-muscarinic effects)
What is Ranitidine?
A H2 receptor antagonist used to reduce acid secretion in the stomach
What are the ADRs of Ranitidine?
Not many, well tolerated - headache and diarrhoea
What drugs have the warnings and contraindications of masking symptoms of gastro-oesphageal cancer?
Which also have the fracture risk with osteoporosis?
Ranitidine
Omeprazole
Lansoprazole
The PPIs
What are the DDIs of Ranitidine?
Few - reduced exposure to some antivirals and protein kinase inhibitors
What are two examples of PPIs?
Omeprazole
Lansoprazole
What are the ADRs of PPIs?
GI disturbance - abdo pain, constipation, diarrhoea
Headache, dizziness
Drowsiness/confusion (especially in elderly patients)
What are the DDIs of PPIs?
Omeprazole is a CYP inhibitor so reduces clopidogrel’s action (a pro-drug)
PPIs can also increase effects of warfarin and phenytoin so monitor
What are two examples of anti-motility drugs?
Codeine phosphate
Loperamide
What is the action of loperamide?
Specific to mu receptors in the myenteric plexus
What are the side effects of opioid receptor agonists like loperamide, codeine, morphine?
Paralytic ileus
Nausea and vomiting
Sedation and addiction (codeine and morphine)
What are two types of osmotic laxatives and how do each work?
- Lactulose - causes water to move into gut
* Macrogol - retains it’s water
What are 4 examples of stimulant laxatives?
- Bisacodyl
- Docusate sodium
- Glycerol suppository
- Senna
What is the action of stimulant laxatives?
Increase intestinal motility
Given orally or PR
Docusate sodium acts as a stimulant and stool softener
Glycerin suppositories cause rectal irritation and lubrication
What are the bulk forming laxatives?
Ispaghula husk
Methylcellulose
What is the mechanism of action of bulk forming laxatives?
Increase faecal bulk - hydrophilic action abusing gut lumen water retention
“Medicinal fibre”
