Gastrointestinal Drugs: Peptic Ulcer Disease - Ch. 82 Flashcards
Which cells secrete hydrochloric acid and pepsinogen?
HCl = Perietal cells
Pepsinogen = Chief cells
What is the purpose of parietal cells?
Produce and secrete HCl to keep stomach at pH of 1 to 2
What cells are the primary site of action for many acid-controller drugs?
Parietal cells
What do ECL stomach cells secrete?
Secrete histamine which stimulate parietal cells
What are stomach acid-related diseases?
Action of acidity on digestive tract integrity?
What is the purpose of drug therapies for stomach acid related diseases?
Eradicate H. pylori if present in the stomach
Reduce gastric acidity
Enhance mucosal defenses
90% of clients with what are found to have H. pylori?
Duodenal ulcers
70% of clients with what are found to have H. pylori?
gastric ulcers
What is used to eradicate H. pylori?
Antibacterials
Rates of what is much less when H. pylori is eradicated?
Recurrence rates are much lower
What are the inhibitors of Gastric acid secretion/action?
H2 antagonists
proton pump inhibitors
Antacids
other agents - protect mucosa
What are kinds of antacids?
Magnesium salts
Calcium salts
Sodium bicarbonate
Aluminum salts
What are H2 antagonists?
Reduce acid secretion
All available in OTC in lower dosage forms
Most popular drugs for treatment of acid-related disorders
Examples of H2 antagonists?
Cimetidine (Tagamet)
Famotidine (Pepcid)
Ranitidine (Zantac)
Nizatidine (Axid)
What is the mechanism of action of H2 antagonists?
Block histamine H2 receptors of acid-producing parietal cells
(receptor antagonist)
-Decreases HCl production
What are H2 antagonists used for?
GERD (gastro-esophogeal reflux disease) -erosive esophagitis
PUD (peptic ulcer disease)
Adjunct therapy in control of upper GI bleeding
Pathological gastric hypersecretory
conditions
What adverse effects are associated with h2 antagonists?
Low incidence of AEs
Cimetidine may induce impotence and gynecomastia (antiandrogenic effect)
In elderly; CNS depression, lethargy, confusion, renal/hepatic impairment
What interactions does H2 antagonist: Cimetidine have?
Inhibits liver cytochrome P-450
Affects metabolism of ofter drugs causing increased drug levels e.g, warfarin
extra care should be taken for patients with what who are taking Cimetidine?
Impaired renal or liver function
Cimetidine should be used with caution in what group of patients?
Confused, disorientated or elderly patients
Cimetidine should be taken 1 hour before what?
Antacids
-Affects absorption
What are Proton pump inhibitors (PPI)?
Inhibits the pump that moves H+ into the stomach lumen
more effective than H2 antagonists
What is the mechanism of action of PPIs?
Irreverisbly bind to H+/K+ ATPase enzyme (proton pump)
What does normal acid secretion require?
Normal acid secretion needs parietal cell to synthesise new H+/K+ ATPase
Examples of PPI?
Omeprazole
lansoprazole
rabeprazole
pantoprazole (Pantoloc) -IV option
esomeprazole
(all very similar)
Describe Omeprazole?
Enteric coated
Broken down by acid
What are proton pump inhibitors used for?
GERD maintenance therapy
Erosive esophagitis
Short-term treatment of active duodenal and benign gastric ulcers
Zollinger-Ellison syndrome (gastrin-producing tumour)
What are PPI safe for?
Short-term therapy
- 4-8 weeks
What adverse effects are associated with PPI?
Incidence of AE low and uncommon
-Headaches, Nausea, vomiting, diarrhea
When should you use PPI with caution?
Liver disease pt
What drug interactions do PPI have?
May inhibit the absorption of drugs that require an acidic GI environment for absorption
e.g, Ketoconazole (anti fungal)
What is the typical therapy for H. pylori infection?
“triple therapy”
-Antibiotics e.g, amoxicillin + clarithromycin
-Proton pump inhibitor e.g, omeprazole
7-14 days
proton pump inhibitors may cause increase serum levels of what?
Diazepam
phenytoin
increased chance for bleeding with warfarin (P450 inhibition)
What should you teach a client if they are taking omeprazole?
Swallow it whole
-Not crushed, opened or chewed because of the enteric coating
It may be given with antacids
Short term treatment only
What is the mechanism of action of Antacids?
Chemically neutralise acid
-Do not prevent acid production
What OTC formulations of Antacids are available?
Capsules, tablets
Powders
Chewable tablets
Suspensions
Effervescent granules and tablets
What are the salts in aluminium salts?
Carbonate, hydroxide salts
What can aluminium salts may cause?
constipation
Often with magnesium salts to counteract constipation (can cause diarrhea)
Examples of aluminium salts?
aluminum hydroxide (amphogel)
Aluminum carbonate
Combination products (aluminium and magnesium)
What are the salts in magnesium salts?
Carbonate, hydroxide and oxide trisilicate
What do magnesium salts commonly cause?
Diarrhea
(usually used with other agents to contract diarrhea)
When is magnesium slat use dangerous?
If you have renal failure
-accumulation
Examples of magnesium salts?
Hydroxide salt; Magnesium hydroxide
Carbonate salt
combination products (Al + Mg)
What salts are Calcium salts?
many but carbonate is most common
What may be caused by calcium salts?
Constipation
Kidney stones
How is calcium salts often advertised?
Extra source of dietary calcium
Example of calcium salts?
Calcium carbonate (TUMS)
Describe sodium bicarbonate?
Highly soluble
Quick onset, short duration
What may be caused by sodium bicarbonate?
May cause metabolic alkalosis
The sodium content in sodium bicarbonate may cause problems in clients with what conditions ?
heart failure
hypertension
renal insufficiency
What adverse effects are associated with antacids?
Minimal and depend on compound used
Aluminum and calcium salts = constipation
Magnesium salts = diarrhea
Calcium carbonate = constipation, gas and belching
What drug interactions do antacids have?
May reduce absorption of other drugs if given at the same time
Can cause chelation
What is chelation?
Chemical binding, or inactivation, of another drug
- Produces insoluble complexes
- reduced drug absorption
eg tetracycline
What should be assessed for before antacid administration?
Allergies
preexisting conditions such as:
Fluid imbalances
Renal disease
HF
Pregnancy
GI obstruction
Clients with heart failure and hypertension should use which antacids?
Low sodium antacids
Most medications should be given how many hours after an antacid?
1-2 hours after giving an antacid
Antacids may cause ____________ _______________ of enteric coating meds
Premature dissolving
Antacids should be administered with what to enhance dispersion?
At least 240 mL of water
-Not needed for rapid dissolving forms
What may aggregate underlying GI conditions when using antacids?
Caffeine
alcohol
harsh spices
black pepper
What are the other agents that protect the mucosa?
Sucralfate
Misoprostol (Cytotec)
What is sucralfate?
Cytoprotective agent
Forms gel with mucus in low pH
Attracted to and binds to the base of ulcers and erosions (forms a protective barrier)
Inhibits pepsin
What is sucralfate used for?
Intestinal erosions
What may be caused by sucralfate?
Constipation
Nausea
Dry mouth
There is little absorption of sucralfate in what area?
gut
Sucralfate may impair the absorption of what the drugs?
Tetracycline
Digoxin
Why might sucralfate be used in chronic renal failure?
Reduce phosphate levels because it binds with phosphate
What is Misoprostol?
Synthetic prostaglandin (PGE1) analogue
-Does the job of endogenous PGs (PHI2 and PGE2)
Prostaglandins have cytoprotective activity
What does cytoprotective activity do?
Production of mucous and bicarbonate
Reduce acid secretion
Promote local cell regeneration
help maintain mucosal blood flow
What is misoprostol used for?
Reduce gastric effects of NSAIDs
When is misoprostol not used?
Pregnancy
-Terminates pregnancy
Example of misoprostol combination tablets?
Arthrotec
= Diclofenac + misoprostol
What adverse effects are associated with misoprostol?
Therapeutic doses for duodenal ulcers often produce:
abdominal cramps
diarrhea
PGE may cause contraction of smooth muscle-containing tissues
