Drugs and the GIT Flashcards
How is acid secretion suppressed?
- Proton pump inhibitors
- H2 blockers
- Antacids increase pH
- Alginates
What is Helicobacter pylori and what does it cause?
Gram-negative, microaerophilic bacterium. Acid loving disease colonises the stomach of 40% humans.
Causes peptic ulceration due to acid production and barrier damage. This cause gastritis, gastric+ duodenal ulcers and gastric cancer - Class 1 carcinogen
HP produces urea goes to NH3 + CO2 + H2O goes to NH4+ and HCO3-.
HCO3- neutralises the stomach acid.
Helicobacter pylori infection in the antrum causes?
G-cells to hypersecrete gastrin and decreases antral D-cell somotastatin release.
This leads to hypergastrinaemia and ultimately duodenal ulcers.
Helicobacter pylori infection in the corpus leads to?
Reduced acid secretion and hypochlorhydria. This is highly associated with gastric ulcers.
How to treat Helicobacter pylori infection
Triple-therapy consisting of antibiotics ampicillin, clarithromycin and a proton pump inhibitor.
What does IBD stand for?
Inflammatory Bowel Disease
What does Aminosalicylates treat?
Aminosalicylates treats ulcerative colitis. However the treatment is linked to life-threatening adverse reactions (fever, liver damage). Its therapeutic effects act on the inflamed mucosa of the colon by interacting with damaged epithelium.
Exact mechanism is not known however it is a scavenger of free oxygen-radicals.
Also treats Chron’s disease.
What is the effect of Azathoprine on DNA synthesis?
Azathroprine is a purine analogue that interferes with DNA synthesis and inhibits the proliferation of quickly rapidly dividing cells, especially cells of the immune system.
What is TNF-alpha?
TNF-alpha is the most important inflammatory cytokine involved in host defence, inflammation, apoptosis and activation of immune cell functions. In IBD, TNF expression increases.
Lymphocyte migration within the intestinal mucosa is important in maintaining inflammation mediated by adhesion molecules. Inhibitors to these molecules interfere with the adhesive interactions of endothelial cells and circulating immune cells.
How does inflammation arise on a protein level and how does Corticosteroids regulate it?
Inflammation arises due to an increase in expression of multiple inflammatory proteins. The increased expression is regulated at the level of gene expression through activation of proinflammatory transcription factors.
Corticosteroids regulate this gene expression by binding to glucocorticoid receptor (GP) in the cytoplasm that translocate to the nucleus and binds to glucocorticoid response elements (GRE) in the premotor region of steroid-sensitive genes thereby supressing activation of proinflammatory transcription factors.
What different laxatives are present?
- Stimulant laxatives = increase motility through chemoreceptor activation and the myenteric nerve plexus
- Saline (osmotic) laxatives = Draw water into the bowel through osmosis due to high concentration of osmotic particles.
- Emollient (faecal softener) laxatives = non absorbent lubricants.
- Bulk-forming laxatives = dietary fibre, and products based on fibre i.e. methyl cellulose. (safest and most preferred laxative)
How do anti-diarrhoeals work? Especially how does Loperamide work?
Prolongs transit time of intestinal content. Reduce daily faecal volume, increase viscosity and bulk density and decreases the loss of fluid and electrolytes.
Loperamide is an opioid receptor agonist and acts of the opioid receptors in the myenteric plexus large intestines decrease activity of the myenteric plexus which decreases the motility of the circular and longitudinal smooth muscles of the intestinal, this allows for a longer time substances stay in the intestine, allowing for more water to be absorbed.
How do enterotoxins cause secretory diarrhoea?
The enterotoxin induces intracellular concentrations of cAMP which increases Cl and K secretion and inhibits electroneutral NaCl absorption. Because the secondary messenger doe not alter the function of nutrient-coupled Na+ absorption, administration of an oral rehydration solution containing glucose and Na+ is effective in the treatment of enterotoxin-mediated diarrhoea.
How is anaemia treated?
Ferrous sulphate is a common treatment. Tea and coffee should be avoided and vitamin C should be taken with the iron pill.
