Alimentary Pharmacology Flashcards
What are different categories of drugs for alimentary disease?
Acid suppression
Drugs affecting GI motility
Laxatives
Drugs for inflammatory bowel disease
Drugs affecting intestinal secretions
What are examples of drugs for acid suppression?
Antacids
Alginates
H2 receptor antagonists
Proton pump inhibitors
What are examples of drugs affecting GI motility?
Anti-emetics
Anti-muscurinics/anti-spasmodics
Anti-motility
What are examples of drugs for IBD?
Aminosalicylates
Corticosteroids
Immunosteroids
Biologics
What are examples of drugs affecting intestinal secretions?
Bile acid sequestrants
Ursadeoxycholic acid
What do antacids contain?
Magnesium or aluminium
What do antacids do?
Neutralise gastric acid
When are antacids taken?
When symptoms occur
What is an example of an alginate?
Gaviscon
What is an alginate?
Form of viscous gel that floats on stomach contents and reduces influx
How do H2 receptor antagonists work?
Block histamine receptor therby reducing acid secretion
How are H2 receptor antagonists administered?
Orally or IV
What is an example of a H2 receptor antagonist?
Ranitidine
What is an example of a proton pump inhibitor?
Omeprazole
When are H2 receptor antagonists indicated?
GORD
Peptic ulcer disease
How do proton pump inhibitors work?
Block proton pump and therby reduce acid secretion
When are proton pump inhibitors indicated?
GORD
Peptic ulcer disease
How are proton pump inhibitors administered?
Oral or IV
What are side effects of proton pump inhibitors?
GI upset
Predisposition to C. Difficile infection
Hypomagnesaemia
B12 deficiency
What do prokinetic agents do?
Increase gut motility and gastric emptying
What are examples of prokinetics?
Anti-emetics such as Metoclopramide and Domperidone
What is the mechanism of action of prokinetic agents?
Not clear but involves parasympathetic nervous sytem control of smooth muscle and sphincter tone (via acetylcholine)
What is the mechanism of action for Domperidone?
Blocks dopamine receptors which inhibit post-synaptic cholinergic neurones
What is the physiology behind vomiting?
What different things can be targeted to prevent vomiting?
Chemoreceptor trigger zone
Pharynx and GIT
Vestibular neclei
Cerebral cortex
What is a possible side effect of drugs that decrease motility?
Constipation
What are examples of drugs that decrease motility?
Loperamide
Opiods
What is the clinical benefit of drugs that reduce motility?
Anti-diarrhoea
What is the mechanism of action of drugs that decrease motility?
Decrease smooth muscle contraction, increase anal sphincter tone
What are anti-spasmodics used for?
Reduce symptoms due to IBS or renal colic
What are the 3 mechanisms of anti-spasmodics?
Anti-cholinergic muscurinic antagonists (inhibit smooth muscle contraction in the gut wall)
Direct smooth muscle relaxants
Calcium channel blockers reduce calcium required for smooth muscle contraction
Why does Loperamide have few central opiate effects?
Not well absorbed across the blood brain barrier
What are the 4 types of laxitives?
Bulk
Osmotic
Stimulant
Softeners
What is an example of a bulk laxative?
Isphagula
What is an example of an osmotic laxative?
Lactulose