drugs used in gastrointestinal disordersnur.uobasrah.edu.iq/images/pdffolder/5. git.pdf ·...

$: Drugs used in Gastrointestinal disordersnur.uobasrah.edu.iq/images/pdffolder/5. GIT.pdf · providers recommend calcium supplements during therapy to prevent these types of fractures$
L5: Drugs used in Gastrointestinal disorders

Drugs for Peptic ulcers and duodenal ulcers

Laxatives Drugs

Antiemetic Drugs

Antidiarrheal Agents

19-Mar-19

Dr. Utoor Talib

Drugs for peptic and duodenal ulcers disease

(Antiulcer Drugs)

• Peptic Ulcer Disease (PUD) refers to a group of upper

GI disorders characterized by varying degrees of erosion of

the gut wall.

• Peptic ulcers develop when there is an imbalance between

mucosal defensive factors and aggressive factors

• Gastric acid is an absolute requirement for ulcer formation.

In the absence of acid, no ulcer will form.

19-Mar-19

Dr. Utoor Talib

The most common cause of

PUD is infection with H. Pylori

and the use of NSAIDs.

• Classes of Antiulcer Drugs the antiulcer drugs fall into

five major groups:

1. Antisecretory agents (H2 receptor antagonists, proton pump

inhibitors)

2. Antibiotics

3. Antacids

4. Mucosal protectants

5. Antisecretory agents that enhance mucosal defenses

• The goal of drug therapy is to:

1. Alleviate symptoms

2. Promote healing of lesions

3. Prevent complication (hemorrhage, perforation, obstruction)

4. Prevent recurrences of lesions by decreasing cell-destructive

effects or increasing cell-protective effects.

5. Eradicate Helicobacter pylori.

19-Mar-19

Dr. Utoor Talib

19-Mar-19 Dr. Utoor Talib

Histamine2-Receptor Antagonists –

e.g., Cimetidine (Tagamet)

• Therapeutic Uses

• Drugs are effective in prevention and treatment of gastric

and duodenal ulcers.

• These drugs relief symptoms and promote healing in peptic

ulcer. Duodenal ulcers usually heal in 6 to 8 weeks, and

gastric ulcers may require up to 12 weeks of therapy.

• Drugs also used in treatment of heartburn, gastritis, reflux

esophagitis, GI bleeding, aspiration pneumonitis.

• Cimetidine is well absorbed when given orally, half-life

about 2 hours. Partly metabolized in the liver but mainly

excreted unchanged by the kidney – caution in patients with

renal or hepatic dysfunction.

19-Mar-19

• Adverse effects:

• All H2 antagonists have similar safety profiles: Adverse

effects are minor and rarely cause discontinuation of

therapy.

o Patients who are taking high doses, or those with renal or

hepatic disease, may experience CNS effects – confusion,

restlessness especially in the elderly.

o Gynecomastia due to anti-androgenic effects

o Pneumonia – decrease gastric acidity, which promotes

bacterial colonization of the stomach and secondary in

colonization of the respiratory tract.


• Drug Interactions:

• Cimetadine used less frequently than other H2 antagonists

because of numerous drug–drug interactions (it inhibits

hepatic drug-metabolizing enzymes).

• Ranitidine inhibits drug metabolism, but to a lesser degree

than cimetidine. Famotidine and nizatidine do not inhibit

drug metabolism, in addition these drugs are more potent

than cimetidine in inhibiting gastric acid secretion

• Antacids should not be taken at the same time because the

absorption of the H2 receptor antagonist will be diminished.

Advise clients to take an antacid 2 hours before or after

taking a H2 antagonist.

• H2 antagonist inhibits the metabolism of other drugs as

warfarin, phenytoin, and theophyline.


Proton Pump Inhibitors: (PPIs)

• Omeprazole: the first approved drug and is still widely used.

• Proton Pump Inhibitors used in prevention and treatment of peptic ulcer and treatment of heartburn, gastritis, esophagitis.

• They are drugs of choice for the short-term therapy: the typical length of therapy is 4-8 weeks. Most patients are symptom free after 2 weeks of therapy.

• PPIs reduce acid secretion to a greater extent than the H2-receptor antagonists and have a longer duration of action.

• PPIs promote healing of the ulcer: heal more than 90% of duodenal ulcers within 4 weeks and about 90% of gastric ulcers in 6 to 8 weeks.

• Because the proton pump is activated by food intake, the drug should be taken 20 to 30 minutes before the first major meal of the day. If possible, administer before breakfast on an empty stomach.


Adverse effects:

All PPIs have similar efficacy and adverse effects:

• Headache, abdominal pain, diarrhea, nausea, and vomiting

are the most frequently reported effects.

• Long-term therapy especially in high doses increases the

risk for osteoporosis-related fractures, probably because

they interfere with calcium absorption. Some health care

providers recommend calcium supplements during therapy

to prevent these types of fractures.

• Hypomagnesemia. With long-term use, PPIs can lower

magnesium levels, perhaps by reducing intestinal mg.

absorption.

• Chronic hypochlorhydria also ↓ the absorption of vitamin

B12 which lead to megaloblastic anemia. 19-Mar-19 Dr. Utoor Talib

• Antibiotics for H. pylori eradication

• Colonization of the stomach and duodenum occurs in

almost all patients with duodenal ulcer and in the majority

of patients with gastric ulcer.

• The chronic infection with H. pylori, which establish itself

within the mucous layers → is associated with secretion

of acid and gastrin.

• Not every patient with infection will develop ulcer, there are

other host factors that might be important.

• Antibacterial drugs should be given to all patients with

gastric or duodenal ulcers.

• Successful eradication of H. pylori usually results in long-

term remission of the ulcer, and relapse rates are low.


• The antibiotics employed are Metronidazole, Amoxicillin, Clarithromycin, Tetracycline and Bismuth salts.

• At least 2 antimicrobial drugs are used in combinations in order to

Ensure eradication

Reduce the chance of resistance

Increase efficacy

• All patients with peptic ulcers and confirmed H. pylori infections should be treated with antimicrobial in combination with an antisecretory drugs.

Examples:

• Lansoprazole 20 mg b.d + Clarithromycin 500 mg b.d + Amoxicillin 1g b.d for 10-14 day or

• Omeprazole 20 mg b.d + Clarithromycin 500 mg b.d + Metronidazole 400 mg b.d for 10-14 days


• Bismuth. Bismuth compounds act topically to disrupt the

cell wall of H. pylori, thereby causing lysis and death.

Bismuth may also inhibit urease activity and may prevent H.

pylori from adhering to the gastric surface.

• Bismuth can impart a harmless black coloration to the tongue

and stool. Patients should be forewarned. Stool discoloration

may confound interpretation of gastric bleeding.

• Antacids: alkaline compounds that neutralize stomach

acid. Antacids react directly with gastric acid to produce

neutral salts or salts of low acidity and water.

• Antacids raising gastric PH and therefore reduce irritation by

gastric acid secretion and decrease destruction of the gut

wall.

• Antacids are available in tablet and liquid formulations.

liquids (suspensions) are more effective than tablets.

• Clinical uses of antacids: The primary indication for

antacids are peptic ulcer disease and Gastro-esophageal

reflux disease.

• Antacids can produce symptomatic relief, but they do not

accelerate healing.

• Adverse Effects Some antacids (eg, aluminum hydroxide)

promote constipation, whereas others (eg, magnesium

hydroxide) promote diarrhea.

• Sodium Loading. Some antacid preparations contain

substantial amounts of sodium

• Interactions with antacids: Antacids can bind to drugs in

the GIT and reduce their absorption such as iron, H2

receptor antagonist, tetracycline and digoxin.

19-Mar-19

Dr. Utoor Talib

• Sucralfate is an effective antiulcer medication notable

for minimal side effects and lack of significant drug

interactions.

• Sucralfate produce a viscid and very sticky gel that adheres

to the ulcer crater, creating a barrier against acid and pepsin.

• Sucralfate has no acid-neutralizing capacity and does not

decrease acid secretion.

• Sucralfate is administered orally, and systemic absorption is

minimal (3% to 5%). About 90% of each dose is eliminated

in the feces.

• Adverse Effects. Sucralfate has no known serious adverse

effects. The most significant side effect is constipation,

which occurs in 2% of patients. Because sucralfate is not

absorbed, systemic effects are absent. 19-Mar-19

Dr. Utoor Talib

• Misoprostol (prostaglandin analogue) serve to prevent

peptic ulcers and reduce gastric damage by decrease acid

secretion, increase the secretion of bicarbonate and

protective mucus, and promote vasodilation to maintain

submucosal blood flow.

• Misoprostol primary use is for the prevention of peptic

ulcers in patients who are taking high doses of NSAIDS or

corticosteroids.

• Diarrhea and abdominal cramping are relatively common

adverse effects. Classified as a pregnancy category X drug,

misoprostol is contraindicated during pregnancy.


Laxatives (Purgatives) • Drugs used to promote the evacuation of the bowel, or stimulate

defecation, and are widely used to prevent and treat constipation.

• These agents can soften the stool, increase stool volume, hasten fecal passage through the intestine, and facilitate evacuation from the rectum. When properly employed, laxatives are valuable medications. However, these agents are also subject to abuse.

• The term laxatives implies mild and slower effects and elimination of soft, formed stool over a period of 1 or more days.

• In contrast, the term catharsis refers to a fast and intense effects, and a prompt fluid evacuation of the bowel.

• Most purgatives are available in OTC preparations, including tablet, liquid, and suppository formulations, and they are often abused by people who then become dependent on them for stimulation of GI movement. Such individuals may develop chronic intestinal disorders as a result.


Classification:

• Chemical stimulant laxatives

• Bulk stimulant laxatives

• Surfactant Laxatives – Lubricants

• Osmotic laxatives

• The type of purgatives recommended depends on the condition of the patient, the speed of relief needed, and the possible implication of various adverse effects.

• Stimulant laxatives: Stimulation of intestinal peristalsis

promote peristalsis by direct irritating the bowel mucosa. They are rapid acting and more likely to cause diarrhea and cramping. Used for short-term treatment of constipation and client preparation prior to surgery or diagnostic tests such as a colonoscopy

• E.g., Bisacodyl, glycerol, Sodium picosulphate, Senna and castor oil


• Bulk-forming laxatives are the most physiologic laxatives because their effect is identical to the action of dietary fiber. These agents are largely unabsorbed from the intestine which increasing the volume and reducing the viscosity of bowel contents by pulling water into the intestinal lumen.

• E.g., Bran, methylcellulose and polycarbophil.

• Stool Softeners or Surfactant Laxatives: These agents lower surface tension of the stool to allow penetration of water lead to softening of the fecal material, and make the defecation easier without stimulating the peristalsis (Lubricants).

• Patients with hemorrhoids, anal fissure and those who have recently rectal surgery may need lubrication of the stool. Some patients who could be harmed by straining might also benefit from this type of laxative.

• E.g., Docusate, glycerin, and mineral oil.


• Osmotic laxatives: These agents are unabsorbed from the intestine. Consequently, they increase osmotic pressure and draw water into the intestine lumen to increase the mass of stool, distention of the bowel, stretching musculature leads to increased peristalsis. These laxatives are used when rapid bowel evacuation is needed, used to clear the colon in diagnostic procedures as colonoscopy or radiology or in preparation for colonic surgery. E.g., Magnesium salts, lactulose, and polyethylene glycol

Indications:

• Short-term relief or treatment of constipation

• Prophylaxis of constipation – prevent straining when it is clinically undesirable (such as after surgery, myocardial infarction, or obstetrical delivery)

• Soften the stool in painful anal conditions such as hemorrhoids and anal fissure, to evacuate the bowel for diagnostic procedures;


• Occasionally, purgatives are administered to accelerate the

movement of ingested toxins following poisoning or to

remove dead parasites in the intestinal tract following

anthelminthic therapy.

• Measures such as starting proper diet and exercise and

taking advantage of the actions of the intestinal reflexes

have eliminated the need for purgatives in many situations.

Contraindications/Precautions

• Clients with fecal impaction, bowel obstruction, and acute

surgical abdomen to prevent perforation.

Clients with nausea, cramping, and abdominal pain.

Clients with ulcerative colitis and diverticulitis with the

exception of bulk-forming laxatives .

• Use cautiously during pregnancy and lactation.


• Anti-diarrheal drugs

• Antidiarrheal drugs are used to treat diarrhea. Diarrhea is not a disease but a symptom of an underlying disorder.

• Antidiarrheal drugs fall into 2 major groups:

Specific antidiarrheal agents may be used to treat the underlying cause of diarrhea. For e.g., antibiotics may be used to treat diarrhea caused by a bacterial infection and drugs used to correct malabsorption syndromes.

Nonspecific antidiarrheal agents (decrease in frequency and fluid content of stool) and include:

1. Anti-motility drugs: e.g., Codeine, Diphenoxylate and Loperamide. These anti-motility drugs activate opioid receptors in the GI tract to intestinal motility and to the absorption of fluid and sodium in the intestine – fluid content of stool.

2. Drugs increase viscosity of faces as: Kaolin

19-Mar-19

Dr. Utoor Talib

• Diphenoxylate: it is similar to codeine, usually given

mixed with atropine (Lomotil). It can cause nausea,

vomiting, abdominal pain and CNS depression.

• Loperamide is an analog of the opioid, but it has no

narcotic effects, does not elicit morphine-like symptoms.

• Antidiarrheal drugs should never be used to treat diarrhea

caused by poisoning or infection with toxin producing

organisms. Use of antidiarrheal drugs in these

circumstances will retain harmful substances in the body.

• All the anti-motility drugs should not be given to children

with acute diarrhea it may cause paralytic ileus &

respiratory depression.


Antiemetic drugs • A large number of antiemetics are available to treat or prevent

nausea and vomiting (generally more effective in prophylaxis

than treatment).

• Selection of a particular agent depends on the experience of the

health care provider and the cause of the nausea and vomiting.

• Most antiemetic drugs relieve nausea and vomiting by acting on

the vomiting center, chemoreceptor trigger zone (CTZ), in the

brain.

• Antiemetic drugs include:


Drugs Mechanism of antiemetic

action

Therapeutic uses

Glucocorticoids:

Dexamethasone

unknown chemotherapy-induced

nausea and vomiting

Substance P/neurokinin1

antagonists: Aprepitant

Inhibits receptor for substance

P/neurokinin1 in the brain.

chemotherapy-induced

nausea and vomiting

Serotonin antagonist:

Ondansetron

Blocking the serotonin

receptors in (CTZ), and

afferent vagal neurons

chemotherapy, radiation

therapy, and postoperative

Dopamine antagonists:

Prochlorperazine

Blocking the dopamine

receptors in the CTZ.

chemotherapy, opioids, and

postoperative recovery

Anticholinergics:

Scopolamine

Blocking muscarinic receptors simple nausea, motion

sickness

Antihistamines:

Dimenhydrinate

Blocking histamine1 receptors

and muscarinic receptors

simple nausea, motion

sickness


• Nursing considerations /Interventions

Encourage the patients for appropriate lifestyle changes.

Teach the patients carefully about the drugs for accurate administration, including the drug name and prescribed dosage, measures to help avoid adverse effects and to follow appropriate administration guidelines, include:

H2 -receptor blockers: May be taken without regard to mealtimes. Do not take concurrently with antacids unless the drug is available in a combination product.

Proton pump inhibitors: Take 30 minutes before meals. If once-a-day dosing is ordered, take the drug in the morning before breakfast. Do not continue taking the drug beyond 3 to 4 months unless directed by the health care provider. Antacids: Take 2 hours before or after meals with a full glass of water. Do not take other medications concurrently unless available as a combination product or directed to do so by the health care provider

19-Mar-19

Dr. Utoor Talib

Do not administer laxatives if bowel obstruction is possible.

Do not administer antidiarrheal drugs if infection is possible.

Administer antiemetics 30 to 60 minutes before anticipated

nausea-inducing travel or drug administration (e.g.,

chemotherapy) –Antiemetics are most effective when taken

before nausea occurs.

Continue to monitor abdominal assessment findings –

immediately report to the health care provider any significant

increase or decrease in bowel sounds, distention, new onset

or increase in discomfort or pain, severe abdominal pain, or

vomiting that is coffee-ground in consistency or contains

blood or blood in stool or tarry stools (Increasing or severe

abdominal pain or blood in emesis or stool may indicate a

worsening of disease or of adverse drug effects)


drugs used in gastrointestinal disordersnur.uobasrah.edu.iq/images/pdffolder/5. git.pdf ·...

Documents