GI (pt 2/5) Antacids, H2 Blockers Flashcards
What are the 4 goals of Antacid Therapy?
1) Reduction of intragastric acidity
-Neutralize the pH of stomach contents already there
-Decrease further production of gastric acid
-Stomach pH is between 1-3; Antacid therapy increases pH to 4-5
2) Mucosal protection:
-Reinforce the lining of the stomach
-Allow ulcerations to heal
-Prevent further bleeding/re-bleeding
3) Stimulation of GI motility and tighten the LES
-Keep gastric contents in the stomach
4) Prevention and treatment of nausea and vomiting, regardless of etiology
-PONV
-Block the central receptors in the Chemoreceptor Trigger Zone and the Vomiting Center
What 3 things stimulate the secretion of HCl?
-Ach
-Gastrin
-Histamine
Gastric secretions can be up to ___ L/day.
2
pH in the stomach is?
1.0 - 3.5
pH of a molecule of HCl acid is?
0.8
An increase in gastric pH should _______ the chance of aspiration pneumonitis.
An increase in gastric pH should decrease the chance of aspiration pneumonitis
Inhalation of gastric fluid causes what?
Aspiration pneumonitis.
-Particulate or liquid stomach contents in the lung hurts the trachea, lung tissue and inhibits gas exchange.
What is the pH of saliva?
6.7
What is the pH of the small intestine?
6.5-7.5
What are antacids?
Drugs that neutralize the acid of gastric contents.
-Were the primary agent for acid-peptic disorders until the release of H2 antagonists and PPIs.
-Nonprescription remedies for the treatment of dyspepsia and acid-peptic disorders.
-Effects last 1-2 hours
Weak bases that react with HCl to form a salt and water.
-Reduce gastric acidity.
Antacids (!!)
Antacids are ___ bases that react with HCl to form ____ and ____.
Antacids are weak bases that react with HCl to form a salt and water. (!! blue box)
-Reduce gastric acidity
What is dyspepsia?
Indigestion
-Upper abdominal discomfort described as a burning sensation, bloating or gassiness or feeling of nausea
What is Pepsin?
An endogenous chemical that increases gastric production.
What physiologic effects happen if the stomach pH is increased to >4.5 ?
-Inactivate pepsin
-Increase gastric motility
-Increase lower esophageal sphincter tone
Why are Particulate Antacids NOT used for pre-op?
!!! Blue Box:
If aspirated, can cause inflammation and granulation tissue.
-Produce a foreign body reaction if aspirated
-Airway mucosa inflammation
-Granulation tissue forms around the particulates leading to a lung infection
-Clinical reports suggest that the inhalation of particulates is as bad as inhalation of acid.
What are the 3 examples of Particulate Antacids?
1) Sodium Bicarbonate (Alka Seltzer)
2) Calcium Carbonate (Tums)
3) Magnesium Hydroxide and Aluminum Hydroxide (Mylanta/Maalox)
What is the example drug of Sodium Bicarbonate (Particulate Antacid)?
Alka Seltzer
What is the MOA of Sodium Bicarbonate Antacids (Alka Seltzer)?
Reacts with HCL to produce carbon dioxide & sodium chloride.
-Belching (from the CO2)
-Metabolic alkalosis
What is the example drug of Calcium Carbonate (Particulate Antacid)?
Tums
What is the MOA of Calcium Carbonate Antacids (Tums)?
Reacts with HCL to form carbon dioxide & calcium chloride (CaCl2).
-Belching (from the CO2)
-Metabolic alkalosis
What is the example drug of Magnesium Hydroxide & Aluminum Hydroxide Particulate Antacids?
Mylanta & Maalox
What is the MOA of Magnesium Hydroxide & Aluminum Hydroxide Antacids (Mylanta & Maalox)?
Reacts slowly with HCL to form magnesium chloride or aluminum chloride and water.
What is the unique side effect associated with Magnesium Hydroxide?
Mg = must go
Diarrhea