What is the mechanism of action of Gaviscon?
It is a weak alkali so it neutralises stomach acid
Alginate component increases stomach content viscosity to decrease acid reflux
What are the indications for gaviscon?
Pit is symptomatic relief for:
- gastric/duodenal ulcers
- gastro-oesophageal reflux
- non-ulcer dyspepsia
What are the contra-indications for gaviscon?
Hypophosphataemia (Al/Mg salts)
Renal impairment (Mg salts)
What are the side-effects of gaviscon?
Magnesium salts = diarrhoea
Aluminium salts = constipation
What are the interactions of gaviscon?
It decreases absorption of = ACE inhibitors, antibacterials, digoxin, iron
It increases excretion of Lithium
What class of drug is ranitidine?
H2 antagonist
What is the mechanism of action of ranitidine?
It competitively inhibits histamine actions at all H2 receptors, mainly inhibiting gastric acid secretions
Inhibits histamine/gastrin-stimulated secretions
What are the indications for Ranitidine?
Benign gastric/duodenal ulcers
Chronic episodic dyspepsia
GORD
What are the side effects of ranitidine?
Diarrhoea
GI/LFT disturbances
Headache/dizziness/fatigue
Rash
Rare: pancreatitis, bradycardia, AV block
What are the interactions of ranitidine?
Cimetidine: inhibits P450 enzymes ⬇️ metabolism of oral anticoagulants, phenytoin, carbamazepine, quinidine, nifedipine, theophylline, TCAs
What class of drug is omeprazole?
Proton Pump Inhibitor
What is the mechanism of action of omeprazole?
Inhibits gastric acid secretion by dose-dependent inhibition of proton pump of gastric parietal cells
(blocks the hydrogen/potassium pump ATPase enzyme in parietal cells)
90% effective inhibition
What are the indications for omeprazole?
GORD dyspepsia Oesophagitis Gastric/duodenal ulcers H. Pylori eradication Zollinger-Ellison syndrome
What are the cautions of omeprazole?
Liver disease
Breast feeding/pregnancy
May mask symptoms of gastric cancer
What are the side-effects of omeprazole?
GI disturbances
Headache
Rare: dry mouth, peripheral oedema, pruritis
What are the interactions of omeprazole?
Inhibits cytochrome p450 = ⬆️ plasma concentration of phenytoin, warfarin
Where is omeprazole eliminated?
80% renal
20% faecal
What class of drug is loperamide?
Anti-diarrhoeal agent
What is the mechanism of action of loperamide?
It acts on opioid u receptors in the my enteric plexus
Inhibits acetylcholine release = inhibits peristalsis
What are the indications for loperamide?
Acute diarrhoea
Chronic diarrhoea
What are the contra-indications for using loperamide?
Active ulcerative colitis
Antibiotics associated colitis
Dysentery
What are the side-effects of loperamide?
Abdominal cramps Dizziness/fatigue Skin reactions (urticaria)
What are the interactions of loperamide?
Desmopressin
What class of drug is Senna?
Stimulant laxative
What is the mechanism of action of Senna?
It is hydrolysed in the colon to produce anthracine glycoside derivatives
These directly stimulate the myenteric plexus = smooth muscle activity and defaecation
What are the indications for Senna?
Constipation
What are the contra-indications of Senna?
Intestinal obstruction
What are the side effects of Senna?
Common: abdominal cramps/diarrhoea
Rare: hypokalaemia, colonic atony
What class of drug is mesalazine?
Aminosalicylate
What is the mechanism of action of mesalazine?
Releases 5-Aminosalicylate acid in the bowel
Unknown mechanism
What are the indications for mesalazine?
Mild-moderate ulcerative colitis
Maintenance of remission
Rheumatoid arthritis
What are the contra-indications of mesalazine?
Salicylate hypersensitivity
Renal impairment
What are the side- effects of mesalazine?
GI effects:
Diarrhoea, nausea, vomiting, abdo discomfort
Rare: blood dyscrasias, low sperm count, tinnitus
What class of drug is gaviscon?
Antacids