GI - stomach acid crap

Question 1

H2 receptor Antagonists

Answer 1

Cimetidine, Ranitidine (ZANTAC), Famotidine (PEPCID), Nizatidine (AXID)

Question 2

H2 receptor antagonists

Answer 2

1. antagonize H2 receptors (dec cAMP production, and dec production and dec the activity of the H+/K+ ATP-ase
2. Indications:
   - used for gastric, and duodenal ulcers
   - adjunts to gastoesophageal reflux
   - tx zollinger ellison syndrome
   - tx nocturnal acid secretion
   - given pre-op to dec the acid content of the stomach
   - prevent development of ulcers in response to stress
   - tx severe allergic reactions (dec H2 mediated vasodilation in conjunction with H1 antagonists)
   - High doses of cimetidine can be used to tx masculinization (at high doses cimetidine is anti-androgenic)
3. metabolized by the liver
   - cimetidine, ranititinde, and famotidine have injectable forms
4. SE
   - HA, dizziness, nausea, myalgia, itching, rash- seen in elderly pts with impaired renal function
   - chronic cimetidine- with high doses: anti-androgen - loss of libido, impotence, and gynecomastia
5. Drug Interactions
   - Cimetidine inhibits CYP3A4- therefore dec. metabolism of warfarin, phenytoin, etc. (see list on ho pg. 6)
   - Other H2 inhibitors do not inhibit CYP34A
   - alteration of the gastric pH may alter bioavailability of drugs that are absorbed at a low ph

Question 3

Proton pump inhibitors (drug list)

Answer 3

Omeprazole (PRILOSEC), esomeprazole (nexium), lansoprazole (PREVACID), rabeprazole (aciphex), pantoprazole (PROTONIX)

Question 4

Proton Pump Inhibitors

Answer 4

1. irreversibly inhibit the proton pump the final stage of acid production by binding to the H+/K+ ATP-ase in the parietal cell
2. Indications
   - DOC for GERD (administer for a minimum of 1-2 months for tx, maintenance of GERD)
   - Tx for gastric and duodenal ulcers and prevent development of ulcers in ppl using NSAIDs
   - high doses tx zollinger ellison syndrome
3. Prodrugs- administered in the inactive form- which is highly lipophilic- activated in the parietal cells to the active sulfenamide in the presence of gastric acid- become trapped in the cell (irreversible)
   - effect lasts 24-48hrs and takes 2-5days to produce a significant effect
   - take on an empty stomach
   - metabolized in the liver microsomal enzymes
4. SE
   - nausea, vomiting, diarrhea, abdominal colic
   - dec. absorption of calcium: osteoporosis
   - dec absorption of mg: hypomagnesemia- muscle spasms
   - inc. cough and URI esp pneumonia,
   - potential for bacterial overgrowth with long term use (bc of change in pH)
5. Drug interactions
   - omeprazole (prilosec)- inhibits CYP2C19- dec met. of phenytoin, cyclosporine, diazepam, and warfarin
   - omeprazole inhibits conversion of clopidrogel to action compound
   - All other PPI: warfarin interaction

Question 5

Sucralfate

Answer 5

1. cyroprotective agent- Al salt of sulfated sucrose-
2. Indications
   - form protective barrier on the epithelium and exposed proteins in the crater of a stomach ulcer
3. Most effective when taken before meals
4. SE
   - constipation, dry mouth, abdominal discomfort
5. Drug interactions
   - inc absorption of digitalis, tetracycline, and phenytoin
   - avoid antacids 1hr before and after taking sucralfate

Question 6

Misprostol

Answer 6

1. Cytoprotective Agents - prostaglandins E1 analogue- inc secretion of mucus, decreases acid secretion
2. used to prevent ulceration induced by NSAID’s
   - used in conjunction with dinoprostone to induce abortions
3. SE
   - diarrhea, abdominal distress, headache, and dizziness

Question 7

Antimicrobial agents and tx of peptic ulcer

Answer 7

• specifically tx against helibacter pylori drugs: metridonazole, amoxicillin, tetracycline, and clarithromycin
  antibiotic and anti-ulcer drugs combo paks: helidac, tritec