38- drugs used to treat GI disorders Flashcards
what are gastric antacids? (Antacids)
Gastric antacids are weak bases that react with gastric hydrochloric acid to form a salt and water. The net result is increased gastric pH.
Name the active ingredients of antacids? (Antacids)
Calcium carbonate (tums) Aluminum hydroxide Magnesium hydroxide (milk og Magnesia)
List of major side effects of each. (Antacids)
Calcium carbonate´s side effects include nephrolithiasis and fecal compaction.
Aluminium hydroxide reacts with hydrochloric acid to form aluminium chloride, with is insoluble and causes constipation.
Magnesium hydroxide produces magnesium salt, which, because they are poorly absorbed, cause the diarrhea commonly associated with this compound .
What facts increase gastric acids secretion?
Three principal agonists control gastric acid secretion: histamine, acetylcholine and gastrin.
What biochemical mechanism do these three factors share? (H2-receptor blockers)
the final common pathway of these compounds is through activation of the H+/K+ - ATPase proton pump.
How effective are H2-receptor blockers in reducing gastric acid? (H2-receptor blockers)
H2-receptor blockers are capable of reducing more than 90% of basal secretions of gastric acid after a single dose.
Do these agents have additional therapeutic value? (H2-receptor blockers)
They have been shown to be effective in promoting the healing of duodenal and gastric ulcers as well as relieving esophageal reflux disease.
Name four H2.receptor blockers (H2-receptor blockers)
- Cime tidine (Tagamet)-prototype
- Ranitidine (Zantac)
- Famotidine (pepcid)
Nizatidine(Axid)
How can H2-blockers be given? (H2-receptor blockers)
IV or PO
What are the side effects of H2-receptor blockers?
In genral they are well tolerated longest clinical experience is with cimetidine, but the other drugs associated with this class are similar. Most common side effects include nausea headache, dizziness. Cimetidline is known to create unwanted endocrinological effects such as gynecomastia and elevated serum prolactin levels (resulting in galactorrhea). Confusional states in the elderly may be seen.
Are there any important drug-drug interactions associates with H2-blockers? (H2-receptor blockers)
Yes. Cimetidine is a strong inhibitor of cytochrome p-450 system and therefor can slow the metabolism of drugs normally broken down through this system. Examples include warfarin, quinidine, benzodiazepine, procainamide, and phenytoin.
Name five prion pump inhibitors(Proton pump inhibitors)
Omeperazole (Prilosec)-prrototype Lansoprazole (Prevacid) Rabeprazole (aciphex) Pantaoprazole (protonix) Esomeprazole (Nexium)
Explain how these drugs work. (Proton pump inhibitors)
these drugs become active in an acidic environment and irreversibly inhibit the H+/K+- ATPase proton pump on the luminal surface of parietal cells.
When would administering this type of drug be useful? (Proton pump inhibitors)
for patients with esophageal reflex, duodenal or gastric ulcer, multiple endocrine neoplasia (MEN), or a hypersecretory condition such as Zollinger - Ellison syndrome. Also used in combination with antibiotics to eradicate H. pylori
How effective are proton pump inhibitors?(Proton pump inhibitors)
they can inhibit 100% of gastric acid secretion with a singe daily dose.
How are the potential side effects?(Proton pump inhibitors)
most commonly these drugs are well tolerated but they can cause nausea or diarrhea. in animal (not human) studies, long-term administration of large doses of omperazole has caused development of gastric carcinoid tumors.
How are they administrated? (Proton pump inhibitors)
PO og IV
Name the drugs belonging to this class. (Mucosal protective agents)
Sucralfate (carafate)
Bismuth
Misoprostol (Cytotee)
What is Sucralfate?
sucralfate is a sulfated disaccharide developed for use in treating peptic ulcer disease.
What is its major mechanism of action? (Sucralfate)
polymerization and selective binding to necrotic ulcer tissue, where it acts as a barrier to acid , pepsin and bile.
what other action is possible? (Sucralfate)
Sucralfate may also directly absorb bile salts and may stimulate endogenous prostaglandin synthesis.
can sucralfate be taken with H2.receptor blockers or proton pump inhibitors? (Sucralfate)
No. Sucralfate requires an acid pH to be activated and should not be administered simultaneously with either H₂-receptor blockers or proton pump inhibitors.