Drugs Act on Hyper Acidity

8/7/2019 Drugs Act on Hyper Acidity

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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Cisapride - withdrawn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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Drugs Act on Hyper Acidity