Acid Control

Question 1

What are the two main stomach secretions, and what cells produce them?

Answer 1

HCL - parietal cells
Pepsinogen - chief cells

Also mucus, bicarbonate, prostaglandins

Question 2

What are the differences between parietal and ECL cells?

Answer 2

Parietal

• Function is to keep pH at 1-2
• Primary site of action for acid-controlling drugs

ECL

• Secrete histamine
• Stimulate parietal cells

Question 3

Helicobacter pylori (H. pylori) disease incidence and treatment

Answer 3

• Found in 90% of clients with duodenal ulcers and 70% with gastric ulcers
• Antibiotics used to eradicate
• Recurrence rates lowered with eradication

Triple therapy

• Antibacterials (amoxicillin + clarithromycin)
• Proton pump inhibitor (omeprazole)
• 7-14 days

Question 4

What are the 3 inhibitors of gastric secretion/action?

Answer 4

H2 antagonists
Proton pump inhibitors
Antacids (Mg/Ca/Al salts, sodium bicarbonate

Question 5

What is the function of H2 antagonists and what is an example?

Answer 5

• Cimetidine (Tagamet)

Most popular drugs for treatment of acid-related disorders

Reduces acid secretion by blocking histamine (H2) receptors in parietal cells. Leads to decreased production of HCL

Question 6

When should H2 antagonists be used?

Answer 6

GERD (gastro-esophogeal reflux disease)
PUD (peptic ulcer disease)
To control upper GI bleeding, and hypersecretory conditions

Question 7

What are the adverse effects of H2 antagonists?

Answer 7

Low incidence of adverse effects

Cimetidine may cause impotence and gynecomastia (enlarged breast tissue in men)

The elderly may see CNS depression, confusion, renal/hepatic impairment.

Question 8

What are some drug interactions with cimetidine?

Answer 8

Inhibits liver cytochrome P-450

Affects metabolism of other drugs like warfarin. This can cause increased chance for bleeding

Question 9

When should you be cautious when using H2 antagonists?

Answer 9

• With patients who have impaired renal or liver function
• Patients who are confused, disoriented, or elderly
• Take 1 hour before or after antacids*

Question 10

What is the function and an example of proton pump inhibitors (PPI)?

Answer 10

• Omeprazole (Losec or Prilosec)
• Enteric coated, broken down by acid
• Inhibits the pump that moves H+ into stomach lumen, reducing gastric secretion
• It irreversibly binds to H+/K+ ATPase enzyme (proton pump)
• Normal acid secretion requires parietal cells to synthesize new H+/K+ ATPase

Question 11

When should you use PPI’s?

Answer 11

GERD maintenance therapy
Erosive esophagitis
- *Short-term treatment of active duodenal and benign gastric ulcers
- Zollinger-Ellison syndrome (gastrin-producing tumour)

Question 12

What are the adverse effects of PPI’s?

Answer 12

• Only safe for short term therapy (4-8 weeks)
• Low incidence of headaches, GI (nausea, vomiting, diarrhea)
• Use cautioned in patients with liver disease

Question 13

What is a drug interaction that could occur with PPI’s?

Answer 13

May inhibit drugs that require an acidic environment for absorption
eg. Ketoconazole (antifungal)

Question 14

Drug interactions for PPI’s?

Answer 14

Diazepam
- BZD used in many CNS condition

Phenytoin used in epilepsy

Causes an increased chance of bleeding with warfarin

Question 15

Antacids: Aluminum Salts

Answer 15

*Aluminum hydroxide (Amphogel)

Salts - carbonate, hydroxide
May cause constipation, but use with magnesium salts to counteract constipation

Question 16

Antacids: Magnesium Salts

Answer 16

*Magnesium hydroxide

Salts: carbonate, hydroxide, oxide, trisilicate

• Commonly causes diarrhea
• Dangerous when used with renal failure (accumulation)

Question 17

Antacids: Calcium salts

Answer 17

*Calcium carbonate (TUMS)

Salts: many but carbonate is most common

• May cause constipation
• Possible kidney stones

Question 18

Antacids: Sodium Bicarbonate

Answer 18

• Highly soluble
• Quick onset, but short duration
• May cause metabolic alkalosis
• Sodium content may cause problems in clients with HF, hypertension, or renal insufficiency

Question 19

What are some adverse effects of antacids?

Answer 19

Minimal depending on compound

Al and Ca
- Constipation

Mg
- Diarrhea

Calcium Carbonate

• Constipation
• Gas and belching
• often combined with simethicone

Question 20

What are some drug interactions with antacids?

Answer 20

May impact absorption of other drugs (gastric motility)

• Chelation
• Chemical binding, or inactivation of another drug
• Produces insoluble complexes . (reduced drug absorption eg tetracycline)

Question 21

What are some care implications for antacids?

Answer 21

Clients with HF or hypertension should use low-sodium antacids

Most medications should be given 1-2 hours after giving an antacid

Administer with at least 240 mL of water to enhance dispersion

Question 22

What two drugs protect the mucosa?

Answer 22

• Sucralfate
• Binds directly to ulcer surface and forms a protective barrier
• Used for stress ulcers, erosions, PUD
• Forms gel with mucus in low pH
• Do not administer with antacids
• Inhibits pepsin
• May cause constipation, nausea, and dry mouth
• May impair absorption of other drugs
• Binds with phosphate, may be used in chronic renal failure to reduce phosphate levels
• Misoprostol (Cytotec)
• Prostaglandin (PGE1)
• Prostaglandins have cytoprotective activity
• Production of mucus and bicarbonate
• Reduces gastric effects of NSAID’S
• Used to terminate pregnancy
• Can produce abdominal cramps and diarrhea