Gastrointestinal

Question 1

Name the weak base antacids

Answer 1

• Aluminum hydroxide, Cause constipation
• Magnesium hydroxide, Cause diarrhea
• Commonly combined

Question 2

Stomach mucus secretion pathway

Answer 2

-Gastrin or Ach stimulate mast cells which produce histamine-> bind H2 receptors on parietal cells-> mucus secretion

Question 3

Cimetidine

Answer 3

• H2 receptor antagonist (first)

- Inhibits P450-> effects other drugs

Question 4

Ranitidine

Answer 4

• H2 blocker antacid second generation
• does not effect P450
• Other: Nizatidine, Famotidine

Question 5

Omeprazole

Answer 5

• Antacid, irreversibly inhibit H/K ATPase pump in parietal cells
• Weak base activated in stomach acid, activity restricted to stomach
• obliterates stomach acid production for 24-48hr
• Primary treatment for Gastroesophageal reflux disease(GERD)
• Other: lansoprazole, Esomeprazole, Rabeprazole

Question 6

Misoprostol

Answer 6

• Mucosal protective agent, Prostoglandin E1 analog
• Increase in mucus and bicarbonate production
• used when NSAID treatment inhibits endogenous Prostoglandin levels

Question 7

Sucralfate

Answer 7

• Mucosal protective agent
• aluminum hydroxide and sulfated sucrose
• Forms gel with mucus preventing Proton release
• every 6hrs, not absorbed free of side effects

Question 8

Factors effecting peptic ulcers

Answer 8

• Helicobacter pylori, gram negative bacteria-> breakdown mucus layer, immune response-> increased urease-> CO2 & ammonia-> toxic to mucosa
• NSAIDS-> inhibit prostaglandins-> stimulate bicarbonate & mucus
• Gastric acid-> activates pepsin, injures mucosa
• Decreased blood flow-> increase gastric acid secretion, decrease mucus & bicarbonate
• Smoking-> stimulates gastric acid production

Question 9

Bismuth

Answer 9

• Antibacterial treatment of peptic ulcer
• disrupts cell wall of H. Pylori
• Amoxicillin, disrupts cell wall of gram negative bacteria

Question 10

Clarithromycin

Answer 10

• Antibiotic, disrupts protein synthesis

- Tetracylin

Question 11

Metronidazole

Answer 11

-Antibiotic used due to resistance to Amoxicillin or Tetracycline, or patient intolerance

Question 12

Peptic Ulcer standard treatment

Answer 12

-Omeprazole, amoxicillin, metronidazole

Question 13

Types of bulk laxatives

Answer 13

• Carbohydrate based

- osmotically active, mgso4, na2so4

Question 14

Ricinoleic Acid

Answer 14

• Small bowel irritant, Castor oil
• triglyceride oil activated, acid released through lipase activity
• Must be purified, contains Ricin potent toxin that inhibits protein synthesis

Question 15

Irritant laxative mechanism

Answer 15

-Irritates enteric mucosa–> more water secreted than absorbed–> softer bowel content, increased volume-> increased peristalsis

Question 16

Anthraquinones

Answer 16

• Large bowel irritants, Senna and Rheum, contain inactive glycosides
• Active Anthraquinones released in colon 6-10 hrs

Question 17

Diphenolmethanes

Answer 17

• Large bowel irritants, derivative of phenolphthalein (pyridine attached by methane to 2 benzenes)
• Bisacodyl, Sodium picosulfate

Question 18

How does laxative abuse develop causing constipation?

Answer 18

• entire colon emptied vice just descending colon–> repeated use
• Enteral loss of H2O, salts-> release of aldosterone-> renal reabsorption-> loss of K-> hypokalemia-> reduced peristalsis-> repeated use

Question 19

Loperamide

Answer 19

• Antimotility agent, opiate
• Selective to GI tract
• Combined with Dimethicone(silicon based gs absorbent)