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Drugs act onhyperacidity
AZL & ZRDep. Farmakologi & Terapeutik,
Fakultas KedokteranUniversitas Sumatera Utara
Oktober 2008 KBK Block GIS
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Acid-Related Pathophysiology
The stomach secretes:
Hydrochloric acid (HCl)
Bicarbonate
Pepsinogen Pepsin breaks down proteins (proteolytic)
Intrinsic factor
Mucus Provide a protective mucous coat Protect against self-digestion by HCl
Prostaglandins
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Drugs used in dyspepsia
Anti-acid agents
Antacids / Alginates
H2As
PPIs
Mucosal Protectants
Misoprostol/Prostaglandin
(Sucralfate)
(Bismuth)
Prokinetic Agents
Cisapride - withdrawn
Metoclopramide /
Domperidone
Helicobacter Pylori Agents,
Antibiotics - Hpylori
Amoxycillin
Clarithromycin
Metronidazole
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Antacids: General
Neutralize acid
Prevent/treat PUD, GERD, Esophagitis,
heartburn, gastritis, GI Bleeding and stressulcers.
Separate administration from other drugs
by 1 to 2 hours
For treating of PUD, 1 &3 hours after
meals and at bedtime
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Antacids: Mechanism of Action
Promote gastric mucosal defense
mechanisms, secretion of: Mucus: protective barrier against HCl
Bicarbonate: helps buffer acidic properties ofHCl
Prostaglandins: prevent activation of proton
pump
Antacids DO NOT prevent theoverproduction of acid
Antacids DO neutralize the acid once its
in the stomach
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Antacids
Used alone or in
combination
Aluminum salts Magnesium salts
Calcium salts
Sodiumbicarbonate
OTC formulations
available as:
Capsules and tablets
Powders
Chewable tablets
Suspensions
Effervescent granules
and tablets
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Magnesium Hydroxide/
Aluminum Hydroxide Treatment of PUD pain and to promote
healing Neutralizes gastric acid and inactivating
pepsin Magnesium Hydroxide
Contraindicated with impaired renal function the failing kidney cannot excrete extra
magnesium, resulting in accumulation Aluminum Hydroxide gel (Amphogel)
Choice for clients with chronic renal failure Aluminum does not accumulate
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Antacids: Calcium Salts
May cause constipation
Their use may result in kidney stones
Long duration of acid action may causeincreased gastric acid secretion(hyperacidity rebound)
Often advertised as an extra source of
dietary calcium
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Antacids: Sodium Bicarbonate
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 CHF, hypertension, or renalinsufficiency
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Antacid-Drug Interactions
Adsorption 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 drug absorption
Increased stomach pH
Increased absorption of basic drugs Decreased absorption of acidic drugs
Increased urinary pH Increased excretion of acidic drugs
Decreased excretion of basic drugs
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Patient Teaching: Antacids
Magnesium may cause diarrhea
Calcium or aluminum may cause constipation
Renal patients should not take products
containing Magnesium
Take 1-2 hours or after other medications
1 & 3 hours PC and HS
Antacids may cause premature dissolving ofenteric-coated medications, resulting in stomach
upset
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Histamine Receptor Antagonists
Ex. Cimetidine, ranitidine, famotidine,
nizatidine
Prevention & treatment of PUD,Esophagitis, GI bleeding, stress ulcers,
and Zollinger-Ellison Syndrome
May alter the effects of other drugs
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H2 Antagonists:
Mechanism of Action Block histamine (H2) at the receptors of
acid-producing parietal cells
Production of hydrogen ions is reduced,resulting in decreased production of HCl
Inhibit secretion of gastric acid
Suppressed acid secretion in the stomach
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Famotidine
With or without food
Preferred over cimetidine
Does not inhibit the cytochrome p450system
Renal impairment monitor creatinine
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H2 Antagonists: Side Effects
Overall, less than 3% incidence of side
effects
Cimetidine may induce impotence andgynecomastia
May see:
Headaches, lethargy, confusion, diarrhea,
urticaria, sweating, flushing, other effects
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H2 Antagonists:
Drug Interactions cimetidine
Binds with P-450 microsomal oxidase
system in the liver, resulting in inhibitedoxidation of many drugs and increased
drug levels
All H2 antagonists may inhibit theabsorption of drugs that require an
acidic GI environment for absorption
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Teaching: Histamine Receptor
Antagonists OTC, do not take longer than 2 weeks
Take with or without food
Do not take an antacid for approx 1 hour
before or after taking one of these drugs
SMOKING has been shown to decrease
the effectiveness of H2 blockers
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Proton Pump Inhibitor (PPI)
The parietal cells release positivehydrogen ions (protons) during HClproduction
This process is called the proton pump H2 blockers and antihistamines do not
stop the action of this pump
Mechanism of Action of PPI:
Prevent the movement of hydrogen ions fromthe parietal cell into the stomach
Result: achlorhydria -ALL gastric acidsecretion is blocked
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Proton Pump Inhibitors
Strong inhibitors of gastric acid secretion
Bind to the gastric proton pump and
prevent pumping or release of gastricacid (24 hr action)
Indicated in PUD, Gastritis, GERD, &
Zollinder-Ellison syndrome
Faster relief and healing than H2RAs
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Proton Pump Inhibitors
Total inhibition of gastric acid secretion
lansoprazole (Prevacid)
omeprazole (Prilosec)*
rabeprazole (Aciphex)
pantoprazole (Protonix) available for parenteral administration
esomeprazole (Nexium)
*The first in this new class of drugs
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Teaching: Proton Pump Inhibitors
Instruct the patient taking omeprazole:
It should be taken before meals
The capsule should be swallowed whole, not crushed,
opened, or chewed It maybe given with antacids
Emphasize that the treatment will be short term
Take the medication for the full course prescribed
(4-8 weeks) Polymorphism in drug metabolism, then wide
interindividual variability of its efficacy
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Sulcrafate (Carafate)
Cytoprotective agent Used for stress ulcers, erosions, PUD
Attracted to and binds to the base of ulcers anderosions, forming a protective barrier over these
areas Protects these areas from pepsin, which normally
breaks down proteins (making ulcers worse)
It requires an acid pH to activate
May cause constipation, nausea, and dry mouth May impair absorption of other drugs, especiallytetracycline Binds with phosphate; may be used in chronic renal
failure to reduce phosphate levels
Do not administer with other medications
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Teaching: Sulcrafate
Give approximately 2 hours before or after
other drugs
Take on an empty stomach before mealsand @ HS
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Misoprostol (Cytotec)
Synthetic prostaglandin analog
Prostaglandins
Protect gastric mucosa from injury byenhancing local production of mucus or
bicarbonate
Promote local cell regeneration
Help to maintain mucosal blood flow
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misoprostol
Used for prevention of NSAID-induced
gastric ulcers
Doses that are therapeutic enough to treatduodenal ulcers often produce abdominal
cramps, diarrhea
Do not give to women of childbearing
years unless a reliable method of birth
control can be DOCUMENTED
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Antiflatulents
used to relieve the painful symptoms
associated with gas
several agents are used to bind or alterintestinal gas and are often added to
antacid combination products
OTC antiflatulents
Activated charcoal
Simethicone
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Simethicone
May be mixed in antacid formulation or given
alone
Causes gas bubbles to coalesce Alters elasticity of mucus-coated bubbles, causing them to
break
Used often, but there are limited data to support effectiveness
Aids in the passage of gas through the GI
Give after meal and @ HS Shake liquid preparations thoroughly
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Activated Charcoal
Absorbent Agent
Used in emergency treatment of certainpoisons
If told to give both this and ipecac syrup totreat the poisoning, do not give thismedicine until after vomiting and thevomiting has stopped. This usually takesabout 30 minutes.
Activated charcoal will cause stool to turnblack
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Syrup of Ipecac
Emetic
Use in emergency to induce vomiting
Do not give to unconscious victim
Give 1 dose if vomiting does not occur,may give second dose but no more
Do not give if ingestion of petroleum
based products has occurred
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Test Question
Sulcrafate (Carafate) is ordered. The MAR
reads to administer at 0900, 1300, 1800,
& 2200. What should the nurse do?
a. Call the MD
b. Give as written
c. Change the timesd. Hold the medication
C. Change the times because those are all after meal times!
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Test # 2
For which client diagnosis would Aluminum
Hydroxide (Amphogel) be ordered?
a. Hepatic Impairmentb. Renal impairment
c. Constipation
d. Sinusitis
A. Clients with liver impairment should not be ingesting additional magnesium
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Test #3
A nursing assessment finds the client isdifficult to awaken. The MAR shows thatDiphenoxylate (Lomotil) was given 3
times last night. What order should thenurse expect the MD to write first?
a. Draw a peak drug level
b. Naloxone (Narcan) Statc. Nalbuphine (Nubain) QID
d. D/C Diphenoxylate (Lomotil)
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B
Although Atropine has been added to the
medication to discourage abuse, you
cannot rule out the possibility of this
scenerio
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