Drugs affecting the GI Tract Flashcards
What are the outcomes of GORD?
Oesophagitis
Stricture
BM (barretts metaplasia
OAC (oesophageal adenocarcinoma
How is acid secretion suppressed via drugs?
Proton pump inhibitors (omeprazole)
H2 blockers (ranitidine)
Antacids increase pH
Alginates (Gaviscon)
What is the active ingredient in Gaviscon?
Sodium alginate
How does Gaviscon work?
Calcium mediated polymerisation forms a hydrogel which floats to the surface due to CO2 created by the neutralisation of the stomach acid.
What is helicobacter pyori?
Gram-negative microaerophilic bacterium.
Colonises the stomach of 40% of humans.
Leads to cause of peptic ulceration and thus can cause gastritis.
What can helicobacter pylori cause?
Gastritis
Gastric + Duodenal ulcers
Gastric Cancer (WHO) Class 1 carcinogen
How does helicobacter pylori cause disease?
Urease produced by HP converts
Urea —> H3 + CO2+ H20 —-> NH4+ + HCO3-
HCO3- Neutralises the stomach acid
How is helicobacter pylori treated?
Triple therapy of antibiotics amoxicillin, Clarithromycin and a Proton pump inhibitor
What does Hp infection cause?
Hp infection in the antrum: G-cells to hypersecrete gastrin Decrease antral D-cell somotastatin release hypergastrinaemia ultimately duodenal ulcers
Hp infection of the corpus
leads to reduced acid secretion
Hypochlorhydria.
This is largely associated with gastric ulcers
What is Creon?
Enzymes that are synthetic which are packaged into enteric capsules and hence are protected from the stomach pH. This allows them to get into the small intestine where the capsule ruptures and the enzymes are released.
What is Creon used to treat?
Exocrine Pancreatic Insufficiency (EPI) caused by:
Cystic fibrosis
Chronic pancreatitis where the pancreas doesn’t make enough enzymes.
What is IBD?
2 forms:
Ulcerative colitis (superficial inflammation)
Chrons Disease
What are 5-aminosalicylic acid (5-ASA)?
Used to treat IBD ulcerative colitis.
works by interacting with the damage epithelium to repair it by blocking production and chemotaxis of leukotrienes
What are immunomodulators?
Azathioprine:
Inhibits proliferation of quickly rapidly dividing cells of the immune system and used to treat IBD by interfering with DNA synthesis
What are biologics?
TNF-alpha inhibitors - an inflammatory cytokine that is involved in host defence.
Used to treat IBD
Infliximab, adalimumab, golimumab
What are corticosteroids?
Bind to receptors to suppress inflammation expressed by genes or can also induce anti-imflammatory signals.
What drugs treat IBD?
5-ASAs
immunomodulators
biologics
Corticosteroids
What drugs are used to treat constipation?
Laxatives:
stimulant - senna, cascara
Saline (osmotic) - Mg, sulphate
Emollient (fecal softener)
Bulk forming - Bran, Methylcellulose
Name an anti-diarrhoeal?
Loperamide
How does loperamide work in preventing diarrhoea?
Suppresses the myenteric plexus which decreases the motility of the circular and longitudinal smooth muscles. This increases the amount of time substances stay in the intestine allowing for more water to be absorbed out of fecal matter
Also supresses the Gastrocolic reflex
How can patients with cholera absorb nutrients?
Cholera toxin inhibits electroneutral Na absorption
Rely on Oral rehydration therapy where Na is absorbed through the SGLT1 transporter along with glucose.
How is anaemia treated?
Treated by ferrous sulphate to remedy their Iron deficiency anaemia
