GI Drugs Flashcards
Antacids and Alginates Example
Gavsicon
Antacids and Alginates mechanism of action
Antacids buffer stomach acid by increasing the pH and alginic acid increases stomach content viscosity and reduces reflex
Antacids and Alginates ADRs
Antacids such as aluminium salts cuase constipation
Antacids such as magnesium salts cause diarrhoea
Antacids and Alginates Drug interactions
Can reduce absorption of many drugs so doses should be separated
Increases urine alkalinity which increases aspiin excretion
Antacids and Alginates contra-indications
Patients with renal failure
Patients with diabetes mellitus
Muscarinic receptor antagonist example
Hyoscine hydrobromide
Muscarinic receptor Antagonists mechanism of action
Competitively blocks muscarinic acetylcholine receptors in the vestibular nuclei and at the chemoreceptor trigger zone
Muscarinic receptor Antagonists ADR
Sedation
Memory problems
Glaucoma
Dry mouth
Constipation
Muscarinic receptor Antagonists indications
Motion sickness
H2 receptor antagonists example
Ranitidine
H2 receptor antagonists mechanism of action
Inhibition of histmine 2 receptors which decreases acid secretion
H2 receptor antagonist ADR
Diarrhoea
Headache
However usually well tolerated
H2 receptor antagonist contra-indications
It may mask symptoms of gastro-oesophageal cancer
Renal impairment
Proton pump inhibitor examples
Lansoprazole
Omeprazole
Proton pump inhibitor mechanism of action
They irreversibly inhibit H+ / K+ ATPase in gatsric parietal cells and significantly decreases gastric acid secretions
Antacids and alginates indications
GORD
Indigestion
H2 receptor antagonists inidcation
Gastric ulcers
Duodenal ulcers
Indigestion
GORD
Proton pump inhibitor ADRs
Abdominal pain
Constipation
Diarrhoea
Headache
Dizziness
Confusion and drowsiness
Proton pump inhibitor drug interactions
Omeprazole is a CYP inhibitor
Decreases clopidogrel action
Increases effects of warfarin and phenytoin
Proton pump inhibitor indications
H.pylori eradication
Gastric ulcers
Duodenal ulcers
GORD
Opoid receptor agonist ( anti motility ) examples
Loperamide
Codeine
Morphine
Opoid receptor agonist ( anti motility ) indications
Diarrhoea
Faecal incontinence
Opoid receptor agonist ( anti motility ) mechanism of action
Binds to µ and δ receptors. This decreases tone of longitudinal and circular smooth muscle. It also reduces peristalsis but increases segmental contractions.
There is decreased colonic mass movement by supressing the gastrocolic reflex.
Opiod receptor agonist ( anti-motility ) ADRs
Paralytic ileus
Nausea and vomiting
Sedation
Addiction
Opiod receptor agonist ( anti - motility ) drug interactions
Other pain medications
Osmotic laxatives examples
Lactulose
Movicol
Cosmocol
Osmotic laxatives mechanism of action
Increase the amount of water in the large bowel
Lactulose - draw fluid in
Macrogols - retain water they came in with
Osmotic laxative indications
Constipation
Osmotic laxatives ADRs
Electrolyte imbalance
Flatulence
Nausea
Vomiting
Stimulant laxatives indication
Constipation
Stimulant laxative examples
Bisacodyl
Senna - over the counter
Docusate sodium
Stimulant laxatives mechanism of action
Increases intestinal motility
Stimulant laxatives ADRs
Nausea
Vomiting
Bulk forming laxatives examples
Ispaghula husk
Methylcellulose
Bulk forming laxatives mechanism of action
Increase faecal mass stimulating peristalsis
Bulk forming laxatives indications
Constipation
Bulk forming laxatives ADRs
Abdominal distension
Bulk forming laxatives cautions
Adequate fluid intake should be maintained to avoid obstructions