Exam 4-4 Acid Controlling Drugs Flashcards Preview

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Flashcards in Exam 4-4 Acid Controlling Drugs Deck (43):
1

Cells of the gastric gland

*Parietal Cells
*Mucous Cells

2

Parietal Cells

*Produce and secrete HCI
*Primary site of action for many acid-controller drugs

3

Mucous Cells

*Mucus-secreting cells (surface epithelial cells)
*Provide a protective mucus coat
*Protect against self-digestion by HCL

4

Hydrochloric Acid

*Secreted by the parietal cells when stimulated by food
*Maintains stomach pH 1-4
*Secretion also stimulated by:
large fatty meals
excessive amounts of alcohol
emotional stress

5

Acid-Related Diseases: Characteristics

*Caused by imbalance of the three cells of the gastric gland and their secretions
*Most common: hyperacidity
*Lay terms for overproduction of HCI by the parietal cells:
-ingestion, sour stomach, heartburn, acid stomach

6

Acid-Related Disease:

PUD- peptic ulcer disease
GERD- gastoesophageal reflux disease
Helicobacter pylori (H. pylori)

7

Helicobacter pylori (H. pylori)

*Bacterium found in GI tract of 90% of patients with duodenal ulcers and 70% of those with gastric ulcers
*Can be detected by serum antibody tests
*Antibiotics are used to eradicate H. pylori

8

Types of Acid-Controlling Drugs

*Antacids
*H2 antagonists
*Proton pump inhibitors

9

Antacids: Mechanism of Action

*Neutralize stomach acid
-promote gastric mucosal defense mechanisms
Secretion of:
-Mucus protective barrier against HCI
-Bicarbonate helps buffer acidic properties of HCI
-Prostaglandins: prevent activation of proton pump

10

Antacids do not prevent

the overproduction of acid

11

Antacids neutralize the

acid once it is in the stomach

12

Antacids: Drug Effects

Reduction of pain associated with acid-related disorders:
-Raising gastric pH from 1.3 to 1.6 neutralizes 50% of the gastric acid
-Raising gastric pH 1 point (1.3 to 2.3) neutralizes 90% of the gastric acid
-Reducing acidity reduces pain

13

Antacids

*OTC formulations available as:
-Capsules and tablets
-Powders
-Chewable tablets
-Suspensions
-Effervescent granules and tablets

14

Antacids used alone or in combination with:

-Aluminum salts
-Magnesium salts
-Calcium salts
-Sodium bicarbonate

15

Antacids: Aluminum Salts

*Have constipating effects
*Often used with magnesium to counteract contispation
*Often recommended for patients with renal disease (More easily excreted)
-examples
aluminum carbonate: Basaljel
Hydroxide salt AlternaGEL
Combination Maalox, Mylanta, Di-Gel

16

Antacids: Magnesium Salts

*Commonly cause diarrhea: usually used with other drugs to counteract this effect
*Dangerous when used with renal failure- the failing kidney cannot excrete extra magnesium, resulting in accumulation

17

Magnesium Salts-Examples

-Hydroxide salt- magnesium hydroxide (MOM)
-Carbonate salt- Gaviscon (also a combination product)
-Combination products such Maalox, Mylanta (aluminum and magnesium)

18

Antacids: Calcium Salts/Characteristics

*Many forms, but carbonate is most common
*May cause constipation, kidney stones
*Also not recommended for patients with renal disease- may accumulate to toxic levels
*Long duration of acid action-may cause increased gastric acid secretion (Hyperacidity rebound)
*Often advertised as an extra source of dietary calcium
-example: Tums (calcium carbonate)

19

Antacid: Sodium Bicarbonate/Characteristics

*Highly soluble
*Buffers the acidic properties of HCL
*Quick, onset, but short duration
*May cause metabolic alkalosis
*Sodium content may cause problems in patients with HF, hypertension, or renal insufficiency

20

Antiflatulents are used for

to relieve the painful symptoms associated with gas
-drugs are used to bind or alter intestinal gas and are often added to antacid combination products

21

OTC antiflatulents

*Activated charcoal
*Simethicone
-alters elasticity of mucus-coated bubbles, causing them to break
-used often, but there are limited data to support effectiveness

22

Antacids: Adverse Effects

*Aluminum and calcium
-constipation
*Magnesium
-diarrhea
*Calcium carbonate
-produces gas and belching often combined with simethicone

23

Antacids: Drug Interactions

*Absorption of other drugs to antacids
-reduces the ability of the other drug to be absorbed into the body
Chelation
-chemical binding, or inactivation, of another drug
-produces insoluble complexes
-result reduced absorption

24

Antacids: Drug Interactions-Increased stomach pH-

*increased absorption of basic drugs
*decreased absorption of acidic drugs

25

Antacids: Drug Interactions-Increased Urinary pH-

*increased excretion of acidic drugs
*decreased excretion of basic drugs

26

Histamine 2 (H2) Antagonists

*Reduce acid secretion
*All available OTC in lower dosage forms
*Most popular drugs for treatment of acid-related disorders
-cimetidine (Tagamet)
-nizatidine (Axid)
-famotidine (Pepcid)
-ranitidine (Zantac)

27

H2 Antagonists: Mechanism of Action

*Block histamine at the (H2) receptors of acid-producing parietal cells
*Production of hydrogen ions is reduced, resulting in decreased production of HCl

28

H2 Antagonists: Drug Effect

Suppressed acid secretion in the stomach

29

H2 Antagonists: Indications

*GERD
*PUD
*Erosive esophagitis
*Adjunct therapy in control of upper GI bleeding
*Pathologic gastric hypersecretory conditions

30

H2 Antagonist: Adverse Effects

*Overall very few adverse effects
*Cimetidine may induce impotence and gynecomastia
May see:
-Headaches, lethargy, confusion, diarrhea, urticaria, sweating, flushing

31

H2 Antagonists: Drug Interactions/cimetidine

*Binds with P-450 microsomal oxidase system in the liver, inhibiting oxidation of many drugs and increasing drug levels
*All H2 antagonists may inhibit the absorption of drugs that require an acidic GI environment for absorption

32

Smoking has been shown to-

decrease the effectiveness of H2 blockers

33

Proton Pump Inhibitors

*The parietal cells release positive hydrogen ions (protons) during HCI production
*This process is called the proton pump
*H2 blockers and antihistamines do not stop the action of this pump

34

Proton Pump Inhibitors: Mechanism of Action

Irreversibly bind to H+/K+ ATPase enzyme
-this bond prevents the movement of hydrogen ions from the parietal cell into the stomach
-result achlorhydria-gastric acid secretion is temporarily blocked
*in order to return to normal acid secretion, the parietal cells must synthesize new H+/K+ ATPase

35

Proton Pump Inhibitors: Drug Effect

*Inhibition of gastric acid secretion
-lansoprazole (Prevacid)
-omeprazole (Prilosec)
-rabeprazole (Aciphex)
-pantopraxole (Protonix), (IV form available)
-esomeprazole (Nexium)

36

Proton Pump Inhibitors: Indications

*GERD maintenance therapy
*Erosive esophagitis
*Short term treatment of active duodenal and benign gastric ulcers
*Zollinger-Ellison syndrome
*Treatment of H. pylori- induced ulcers
-Administered with an antibiotic

37

Proton Pump Inhibitors: Adverse Effects

Adverse effects uncommon

38

Other Durgs

*sucralfate (Carafate)
*misoprostol (Cytotec)
*simethicone (Mylicon)

39

Sucralfate (Carafate)/Characteristics

*Cytoprotective drug
*Used for stress ulcers, PUD
*Attracted to and binds to the base of ulcers and erosions, forming a protective barrier over these areas
*Protects these areas from pepsin, which normally breaks down proteins (Making ulcers worse)

40

Sucralfate (Carafate)/Characteristics continued

*Little absorption from the gut
*May cause constipation, nausea and dry mouth
*May impair absorption of other drugs-give other drugs at least 2 hours before sucralfate
*Do not administer with other medications
*Binds with phosphate; may be used in chronic renal failure to reduce phosphate levels

41

Misoprostol (Cytotec)

*Synthetic prostaglandin analog
*Prostaglandins have cytoprotective activity
-Protect gastric mucosa from injury by enhancing local production of mucus or bicarbonate
-Promote local cell regeneration
-Help to maintain mucosal blood flow

42

Misoprostol (Cytotec) is used for

prevention of NSAIDS -induced gastric ulcers

43

Simethicone

*Antiflatulent drug
*Used to reduce the discomforts of gastric or intestinal gas (flatulence)
*Alters elasticity of mucus-coated gas bubbles, breaking them into smaller ones
*Decreases gas pain and increases expulsion via mouth or rectum