Dugga 3 - Antiulcer Flashcards
What are peptic ulcers?
A localised erosion of the mucuos membranes of the stomach (or duodenum)
Where does the pain of ulcers come from?
Irritation of exposed surfaces by stomach acid
What is believed to cause ulcers?
The use of non-steroidal anti-inflammatories (NSAIDS) or the presence of the bacterium called Helicobacter pyroli
How could NSAIDS cause ulcers?
Aspirin for instance inhibit the enzyme cylcooxygenase 1 (COX-1) which is an enzyme responsible for the synthesis of prostaglandins that inhibit acid secretion and protect gastric mucosa
Which drugs are used to treat ulcers?
Cimetidine, ranitidine and proton pump inhibitors (PPIs)
What is omeprazole an example of?
a proton pump inhibitor
Which antibiotics are used against ulcers?
Amoxicillin and metronidazole (against the bacterium Helicobacter pyroli)
Which chemical messengers stimulate the release of hydrochloric acid from stomach parietal cells by acting on receptors?
Histamine, acetylcholine and gastrin
What are H2 antagonists?
Anti ulcer drugs that act on H2 receptors present on parietal cells, they reduce the amount of acid released
What is the proton pump responsible for?
Pumping protons out of the parietal cell in exchange for potassium ions (K+) that are pumped in. It requires ATP.
What advantage does PPIs have over H2 antagonists?
They act on the final stage of hydrochloric acid release
What are PPIs activated by?
The acidic conditions found in canaliculi of parietal cells
What is canaliculi?
It is a deep infolding, or little channel, which serves to increase the surface area, e.g. for secretion.
What are parietal cells?
Parietal cells are responsible for gastric acid secretion, which aids in the digestion of food, absorption of minerals, and control of harmful bacteria.
How are PPI prodrugs activated?
By acid-catalysed rearrangement to form reactive tetracyclic pyridinium sulphenamide which act as irreversible inhibitor. Forms covalent bonds between cysteine and the drug
