GI Pharmacology Flashcards
What are the drug groups used for acid suppression?
Antacids
Alginates
H2 antagonists
PPIs
What is an example of an antacid?
Maalox (aluminium + magnesium)
Rennie (calcium)
How do antacids work?
Neutralise stomach acids by the active base reacting with the acid
What is an example of an alginate?
Gaviscon
How do alginates work?
Alginate forms a gel like raft that sits on top of stomach contents
What is an example of a H2 antagonist?
Ranitidine
How do H2 antagonists work?
Block H2 histamine receptors stopping influx of hydrogen into intestinal lumen
When are H2 antagonists indicated?
Gastric ulcers
GORD
Dyspepsia
What is an example of a PPI?
Omeprazole
Lansoprazole
How do PPI’s work?
Inhibit H+/K+ ATPase proton pump to reduce acid secretion
When are PPIs indicated?
Gastric ulcers
GORD
Dyspepsia
H. pylori eradication
What are the drug groups used for nausea and vomiting?
Antiemetics
What drugs are used against the Chemoreceptor Trigger Zone (CRTZ)?
D2 (dopamine) receptors- haloperidol
5HT3 receptors- ondansetron
What drugs are used against the vomiting centre?
5HT2 receptors- levomepromazine
H1 histamine receptor- cyclizine, levomepromazine
ACH muscarinic receptor- cylcizine, levomepromazine
What drugs are used against the gut?
5HT4 agonist- metoclopramide
DT agonist- metoclopramide
Motilin- macrolide antibiotic
What are the drug groups used for GI motility?
Antispasmodics
Antidiarrheal
Laxatives
What is the function of antispasmodics?
Muscle relaxation
What are the 2 types of antispasmodics?
Antimuscarinics- Buscopan
Calcium channel blockers- peppermint oil
What is the function of antidiarrheals?
Slow down gut motility
What are the types of antidiarrheals
Opioids:
- Loperamide
- Codeine
- Morphine
What are the 4 types of laxatives?
Bulk forming- isphagula
Stool softeners- docusate
Osmotic laxatives- lactulose
Stimulant laxatives- bisacodyl
How do bulk forming laxatives work?
Increase bulk of stool which stimulates stretch receptors increasing peristalsis
How do stool softeners work?
Incorporate more water into stool
How do osmotic laxatives work?
Act as solutes in the fluid in the gut. Sets up concentration gradient for more water to stay in bowel
How do stimulant laxatives work?
Irritate bowel to stimulate it to increase peristalsis
What are the drug groups used for IBD treatment?
- Aminosalicylates
- Corticosteroids
- Immunosuppressants
- Biologics
What is an example of an aminosalicylate?
Mesalazine
What is the function of Aminosalicylates?
Induction and remission of UC
What is an example of a corticosteroid?
Prednisilone
Budseonide
What are the side effects of CORTICOSTEROIDs?
- Cushing syndrome
- Osteoporosis
- Reduced growth
- Thin skin
- Immunosuppression
- Cataracts
- Oedema
- Suppressed HP axis (foetal development)
- Teratogenic
- Emotional disturbance
- Rise in BP
- Obesity
- Increased hair growth
- Diabetes
What is the function of corticosteroids?
Induction of remission in UC and CD
What is an example of an immunosuppressant?
Azathioprine -> 6-mecaptopurine
What are the 2 methods of action of biologics?
Block cytokines
Block recruitments of WBCs
What biologics block cytokines?
Anti TNFa- Infliximab
Anti IL-12/23- Ustekinumab
What biologics block recruitment of WBCs?
Anti-integrin
Vendolizumab
What are the drug groups used for biliary secretions?
Bile acid sequestrants
Bile acid drugs
What is an example of a bile acid sequestrant?
Cholestyramine
What is the indication for bile acid sequestrants?
Pruritis from a biliary cause
What is an example of a bile drug?
Ursodeoxycholic acid
How does ursodeoxycholic acid work?
Inibits enzyme involved in formation of cholesterol and therefore restores the ratio of cholesterol to bile salts so non-calcified gallstones will slowly dissolve
What is the indication for ursodeoxycholic acid?
Non calcified gall stones
Primary biliary cirrhosis
