Pharmacology Final Study Guide

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Pharm Final
Ch 50- Acid Controlling Drugs
* Pathophysiology
* Stomachglands
* Cardiac
* Cardiac sphincter (gastroesophageal)
* Cardiac glands
* Fundic
* Gastric glands- most numerous
* Highly specialized secretory glands composed of: * Parietal cells
* Produce and secrete HCl
* What stimulates? food, chocolate, alcohol, large fatty meals, stress * Chief cells
* Secrete pepsinogen- becomes pepsin breaks down proteins * Mucous cells (surface epithelial cells)
* Secrete mucous that acts as protective coating against the digestive action of HCl and digestive enzymes * Pyloric
* Pyloric glands
* Imbalance in these cells causes disease- hypersecretion: PUD, esophageal cancer, GERD * Over time can lead to: Barrett esophagus
* Acidity of stomach (1-4)= digest food and protect against microbial infection * H. Pylori- 90% pts w/ duodenal ulcer; 70% gastric ulcer * ICU
* Stress ulcer prophylaxis
* NG tubes, ventilator, stay longer than 1wk, occult bleeding, GI bleed, sepsis, steroids= risk for GI lesions * Overview
* Antacids
* MOA
* Neutralize gastric acidity
* Low dose- promote defenses by stimulating secretion of mucus, prostaglandins, HCO3 from cells inside gastric glands * Indications
* ACUTE relief of peptic ulcer, gastritis, gastric hyperacidity, heartburn * Contraindications
* Severe renal failure
* Electrolyte disturbances
* GI obs
* Adv
* Milk of Mag- diarrhea
* Al- constipation
* Ca- constipation, kidney stones, hyperacidity
* NaHCO3- systemic alkalosis, high Na- exacerbate HTN, HF, renal insufficiency * ALL- long term self-medication can mask symptoms of underlying disease like bleeding ulcer or malignancy * Interactions

* Adsorption- antacid absorbs so less of other drug available for body * Chelation- chemical inactivation of other drugs that produces insoluble complexes * Inc stomach pH- inc absorption of basic drugs and dec absorption of acidic drugs * Inc urinary pH- inc excretion of acidic drugs and dec excretion of basic drugs * Quinolones!!- can reduce absorption by 50%

* Drugs
* MANY OTC
* Preg ok- consult doc
* Al- based for renal compromise- more easily excreted * CaCO3- can produce belching/gas- use w/ simethicone * Mg- laxative
* Ca/Mg- accumulate to toxic levels in renal pts * Ca- r/f rebound hyperactidity, milk-alkali syndrome, changes in systemic pH- esp w/ renal dysfunction * H2 Receptor Antagonists

* MOA
* Competitively block H2 receptor of acid-producing parietal cells * Reduce H+ secretion f/ parietal cells inc in pH of stomach and relief of symptoms * Widely used- efficacy, OTC availability, excellent safety profile * Indications

* GERD, PUD, erosive esophagitis
* Stress ulcer prophylaxis
* Adjunct: upper GI bleed, Zollinger-Ellison syndrome * Smoking decreases effectiveness
* Contraindications
* Relative: liver/kidney dysfunction- dosage adj * Adv
* Elderly- confusion, AMS
* Interactions
* Smoking dec effectiveness
* Take 1-2hr b4 antacid
* Drugs
* Cimetidine (Tagamet)
* Largely replaced by other 2
* Treat certain allergic reactions only
* Impotence/gynecomastia...
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