Therapeutic options and referral Flashcards
What are antacids made of and what are some of the brand names?
Antacids consists of magnesium, aluminium, sodium and calcium salts
Brand names include:
Rennies, Tums and Settlers
How do antacids work?
Antacid salts bind to acid within the stomach causing a neutralisation reactions causing release of CO2 (burp).
Alkalinisation can increase the LOS sphincter pressure (reducing GORD) and induce mucosal protection by stimulation of prostaglandin synthesis (allowing ulcer healing).
What are some of the key counselling points for antacids use?
Liquids work more effectively, increased surface area
Tablets should be chewed
Take one after a meal due to reduced gastric emptying (3 hours effect compared to 1hour if not taken after a meal)
Short term use
Not be used as a preventative
Why are antacids limited to short term use?
Presence of antacids causes an increase in pH within the stomach. Acid production increases with pH and therefore can cause acid rebound.
What are some of the indications of antacids?
Functional dyspepsia
Gastric and duodenal ulcers
Oesophagitis
GORD
What are some of the main side effects of antacids?
Aluminium:
Constipation
Osteoporosis (binding to phosphate in the gut)
Neurotoxicity (absorbed)
Magnesium:
Diarrhoea
All can cause acid rebound, therefore only short-term use
When should excessive sodium based antacids be avoided?
In hypertensive / cardiac patients
Are antacids safe for use in pregnancy?
Yes but mindful of sodium content
What drug interactions should you be mindful of with antacid use?
Antacids will damage the enteric coating of some drugs
Binding with tetracyclines and iron based drugs
How do alginates work?
Alginates are formulated with an antacid and once they reach the acidic pH within the stomach they form a high pH viscous mass, essentially a ‘raft’ which traps air and bubbles (due to the antacid reaction causing the release of carbon dioxide which is trapped within the raft).
This rafts sits on top of the stomach and protects the oesophageal mucosa from reflux.
What is the purpose of Simethicone (Dimeticone)?
It is an anti-foaming agent which reduces the surface tension of intra-gastric air bubbles, breaks down the bubble and lets smaller bubbles escape (reducing the feeling of bloatedness).
What are some examples of H2 antagonists?
Cimetidine, Ranotidine, Famotidine, Nizatidine
How do H2 antagonists work?
Compete for H2 receptor binding on parietal cells, preventing activation by histamine and hence acid secretion.
Large stimulus such as a large meal will override these effects.
How does the DOA/onset time compare to that of antacids?
Longer duration of action and time of onset
What are the beneficial outcomes of H2 antagonists on peptic ulcer disease?
High healing rates
However does not affect relapse (has H pylori been eradicated)
What are the beneficial outcomes of H2 antagonists on GORD?
80-90% mild oesophagitis improvement after 12 weeks
Not used for moderate to severe disease
PPI is first line so would only expect use is PPI was not effective
What is the side effect profile like for H2 antagonists?
Only 1-7% experience side effects