GI Therapeutics Flashcards
Name 5 different types of anti-emetics and give an example for each one.
Ouch!
mACH antagonist - Hyoscine H1 antagonist - Promethazine D2 antagonist - Metaclopramide NK1 antagonist - Aprepipant 5HT2 antagonist - Ondanzetron
Types of laxatives
Bulk-forming laxatives Osmotic laxatives Stimulant laxatives Stool softeners Methylnaltrexone Prokinetic agents
What types of drugs may be used to control gastric acid secretion and treat peptic ulcers? Give an example for each treatment
Antacids - aluminium hydroxide, magnesium hydroxide
H2 antagonists - cimetidine, ranitidine, famitidine
PPIs - omeprazole, esomeprazole, pantoprazole
Antibiotics - amoxicillin, clorithromycin
Prostaglandin analogue - misoprostol
Physical agents - sucralfate, bismuth
How do you treat vomiting that is due to pain?
You treat the pain. When the pain subsides nausea goes with its.
Antiemetics that can be used in pregnancy
Promethazine (H1 receptor antagonist)
What anti-emitics are used for chemotherapy?
Ondansetron - 5HT3 antagonist
cannabinoids
What drugs can be used to treat motion sickness?
Hyoscine - H1 antagonist
Promethazine - mAch antagonist
What anti-emetics are used for post-operative nausea?
Ondansetron - 5HT3 antagonist
Antidiarrhoeals
Opioids (eg codeine, loperamide)
Oral rehydration salts
Antispasmotics (cisapride, hyoscine butylbromide, meverine)
Peppermint oil
Bismuth subcitrate mechanism of action
Forms acid-resistant protective coating on ulcer site.
Also had antibacterial properties against H. Pylori.
Use: H. Pylori eradication after fairer of first line treatments
Name 3 kinds of antacids
- Mg2+/Al3+ compounds
- Carbonate/bicarbonates
- Alignates or simeticone
Name 3 H2 antagonist drugs
- Famotidine
- Rantitide
- Cimetidine
Name 5 proton pump inhibitors
- Omeprazole
- Esomeprazole
- Lansoprazole
- Pantoprazole
- Rabeprazole
Name three classes of drugs used to control gastric acid
- Antacids
- Proton pump inhibitors
- H2 antagonists
What are the two major causes associated with peptic ulcer disease?
- Helicobacter pylori
- NSAIDS
How do H. pylori infections lead to peptic ulcers?
Loss of D cells -> decreased somatostatin secretion -> excess gastrin release from G cells -> excess H+ release from parietal cells
Excess acid leads to inflammation and damage -> ulcers
How do NSAIDS lead to ulcer disease?
Systemic effect:
NSAID -> inhibit COX1/2 -> prostaglandin suppression -> loss of prostaglandin-mediated inhibition of acid secretion -> increased acid secretion
Topical effect:
Interaction between NSAID and gastric epithelium -> damage protective mucous barrier
How do prostaglandins protect gastric mucosa?
Stimulate:
- bicarbonate secretion
- mucus secretion
- blood flow
What is the mechanism of action of Antacids?
Neutralise HCl secreted by parietal cells
What is the mechanism of action of H2 antagonists?
Competitively block H2 receptors on parietal cells -> reduced H+ secretion
What is the mechanism of action of PPIs?
IRREVERSIBLY inactivate the hydrogen/potassium ATPase enzyme system (proton pump) -> suppressing both stimulated and basal acid secretion.
(when PPIs are stopped -> synthesis of new hydrogen/potassium ATPase
Prostaglandin analogue used in the treatment of hyper acid secretion
Misoprostol
Treatment for Helicobacter Pylori
PPI + clarithromycin + amoxyiclin
How does H. Pylori cause ulcers?
Causes a loss of somatostatin producing D cells which means gastrin production is no longer inhibited by somatostatin. Increased gastrin results in increased H+ production.
bulk forming laxatives mechanism & example
draw water out of tissues and increases faecal bulk (stimulates peristaltic activity).
eg. fibre
osmotic laxatives mechanism & example
draws water into lumen via osmotic gradient.
eg. sorbitol
lactulose
macrogol
saline laxativesStimulant laxatives mechanism & example
direct stimulation of nerve endings in colonic mucosa (increased motility)
eg. bisacodyl
senna
sodium picosulfate
Stool softeners mechanism & example
softens stool by helping mix water into faeces
eg. docusate
liquid paraffin
poloxamer
prokinetic agents mechanism & example
stimulates motility by increase strength of contractions (5HT4 receptor agonist)
eg. prucalopride
methylnaltrexone
peripherally acting competitive mu opioid receptor antagonist.
blocks constipating effects of opoid.
Doesn’t cross BBB
–> doesn’t inhibit analgesic effects
use when regular laxatives are inadequate
