G.I. Flashcards

1
Q

Peptic Ulcer Disease

A

10-15% of people

Can occur anywhere in the upper GI exposed to stomach acid and pepsin.

Occurs when corrosive action of gastric acid overcomes the protection of mucous.

Helicobacter Pylori and overuse of NSAIDs.

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2
Q

Acid Production

A

Proton from dissociated carbonic anhydrase is pumped from the parietal cell to the lumen of the stomach. Chloride ion follows producing HCL.

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3
Q

Control of Acid Secretion

A

Gastrin produced on the duodenum and stomach stimulating acid secretion by stimulating receptors on parietal cells.

Parasympathetic nerves increases acid production.

Histamine produced near the parietal cells and promote acid production. Histamine is required for the other two mechanisms.

H2 histamine receptor.

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4
Q

Mucosal Defense

A

Mucous secreted by goblet cells

Made up of glycoproteins, water and electrolytes.

Protects from acid and pepsin

Prostaglandins inhibits acid secretion and stimulates mucous production.

Can be inhibited by chemotherapy and extreme stress

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5
Q

H. Pylori

A

Can cause spontaneous ulcers

Antimicrobials are curative

Weakens mucous defense mechanism

Found using endoscopy

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6
Q

Rationale For Therapy

A

Neutralize Acid (antacids)

Inhibit Secretion
- H2 antagonists
-Proton pump inhibitors

Enhance Defense
-Sucralfate
-Misoprostol

Eradicate H. Pylori
-Antimicrobials.

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7
Q

Sodium Bicarbonate

A

Alka Seltzer

HCl + NaHCO3 -> NaCl + H2O + CO2

Possible distension and metabolic alkalosis

Rapid onset

High sodium content

Adequate for occasional relief but not long term treatment

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8
Q

Calcium Carbonate

A

Tums

CaCO3 + 2HCl -> CaCl2 + H2O + CO2

Can cause systemic alkalosis. Less Distension

High Ca intake or poor renal function can cause “milk alkali” including hypercalcemia, kidney stones, and renal damage

Acid rebound

Occasional management

Can decrease bioavailability or glycosides, tetracyclines, and phenytoin.

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9
Q

Magnesium Hydroxide

A

Mg(OH2) + 2HCL -> MgCl2 + 2H2O

Rarely causes alkalosis with magnesium remaining in the lumen

Diarrhea is a common side effect, so coadminister with something with a constipating effect

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10
Q

Aluminum Hydroxide

A

Very much the same as Magnesium Hydroxide, except cause constipation due to astringent effect

Reduces absorption of phosphate causing hypophosphatemia.

Possible development of Alzheimer’s

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11
Q

Maalox

A

Magnesium + Aluminum

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12
Q

Use of Neutralizing Agents

A

Symptomatic relief and act quickly

Not primary for PUD

Many contain significant sodium

Can affect drug dissolution in the stomach and delay gastric emptying.

Na and Ca can raise urinary pH and alter excretion of drugs

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13
Q

H2 Antagonists

A

Cimetidine
- Inhibits CYP450 so drug interactions
-Can have anti androgen effect causing gyno
Famotidine
Nizatidine

Reduce acid secreted in response to histamine.

Used for both acute treatment and prevention of relapse

Zollinger Ellison Syndrome and Reflux -esophagitis

Doesn’t interact with other histamine receptors

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14
Q

Proton Pump Inhibitors

A

-azole

Very effective at reducing acid secretion and have some effect on H. Pylori as well

Inactive prodrugs converted to active form in the parietal cell canniculus. Inactivates H+/K+ ATPase irreversibly.

Effective at treating many acid related conditions

Potential for drug interactions

AE: Possible microbial overgrowth of the upper GI and carcinoid tumors of the stomach.

Osteopenia in women and possible vitamin B12 deficiency

Interaction with Clopidogrel, particularly with Omeprazole and Esomeprazole. Pantoprazole has the least effect. Clopidogrel requires activation by CYP2C19.

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15
Q

Sucralfate

A

Enhance Mucous defense

Polymerizes and forms a coating that binds to proteins in the ulcer.

Should be taken before meals

AE: Constipation

Al is present, so can decrease effectiveness of glycosides and other meds and effect renal function.

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16
Q

Misoprostol

A

Prostaglandin analogue

Increases mucous production

Used to prevent NSAID ulcers

Can induce uterine contractions and and abortions so contraindicated in pregnancy.

Diarrhea, headache and abdominal distress are side effects.

17
Q

Colloidal Bismuth

A

Pepto-Bismal

Coating action to protect stomach and can inhibit pepsin

Has antimicrobial effects that fight H. Pylori.

Can cause Reye’s in children or allergic reactions in those allergic to salicylate.

18
Q

H. Pylori Treatments.

A

Metronidazole with penicillin, tetracycline, or clarithromycin and colloidal bismuth. Need multiple modalities to eradicate.

Helidac therapy is a combined dose pack.

Coadministered with PPI as decreasing stomach acid increases effectiveness of antimicrobials.