Drugs Affecting the Gastrointestinal System and Nutrition

Jan Bazner-Chandler MSN, CNS, RN, CPNP

Acid-related Pathophysiology

Hydrochloric acid (HCL) aids in digestion and serves as a barrier to infection.

Pepsinogen is an enzyme that digests dietary protein.

Mucous protects the lining of the stomach from both HCL and digestive enzymes.

Prostaglandins has an anti-inflammatory and protective function.

Antacids

Are basic compounds used to neutralize stomach acid.

OTC Products

Antacids were the most common products used for acid-indigestion until the 1970’s when histamine-2 (H2 antagonists) were developed.

Action

Primary drug effect of antacids is the reduction of symptoms associated with acid-related disorders: pain and reflux (heartburn)

Raises gastric pH from 1.3 to 1.6.

Indications

Acute relief of symptoms associated with: peptic ulcer disease (PUD) Gastritis gastric hyperacidity Heartburn or gastro esophageal reflux (GEF)

GERD

Most common disorder of esophagus Characterized by regurgitation of gastric

contents into esophagus and exposure of esophageal mucous to gastric acid and pepsin.

Main symptom is heart burn - occurs after eating

Cause is thought to be incompetent lower esophageal sphincter

GERD

Peptic Ulcer Disease

Ulcer formation in the esophagus, stomach or duodenum

Mucous exposed to gastric acid and pepsin Imbalance between cell-destructive and cell-

protective effects Gastric acid and pepsin H. pylori – infectious process

Peptic Ulcer Disease

Adverse Effects

Magnesium preparations especially milk of magnesium or MOM can cause diarrhea.

Calcium products can cause kidney stones. Sodium bicarbonate products can cause

systemic alkalosis. Self-treatment can result in masking

symptoms of a disease (bleeding ulcer or stomach cancer).

Keep away from small children Alkalosis

Contraindications

Allergy to the drug Severe renal failure Electrolyte disturbances Gastro intestinal obstruction

Interaction

May effect absorption of other drugs. Chemically inactivates certain drugs Increased stomach pH decreasing absorption

of acidic drugs

OTC Preparations

Magnesium-containing antacids Gaviscon Liquid, Milk of Magnesium

Aluminum-containing antacids Amphogel, Maalox

Sodium-containing antacids Alka-seltzer, Tums

Gelusil / Mylanta

Administration

Chewable forms needs to be thoroughly chewed.

Liquid forms need to be shaken well before taking.

Take with 8 ounces of water to enhance absorption.

Do not take within 1 to 2 hours of taking other medications – may effect absorption

H 2 Antagonists

H2 receptor blockers cimetadine (Tagamet), ranitidine (Zantac) famotidine (Pepcid) nizatidine (Axid)

H2 antagonist HAs

Action: blocks the H2 receptor of acid-producing parietal

cells Reduce hydrogen ion secretions to increase pH of

stomach

Therapeutic Uses

GERD or gastro-esophageal reflux PUD or peptic ulcer disease Zollinger-Ellison Syndrome (excessive gastric

acidity)

Adverse Effects

Overall very low incidence of adverse effects May cause some CNS effects in the geriatric

patient. Smoking reduces effectiveness H2 antagonist should be taken 1 hours before

taking any antacids

Proton Pump Inhibitors

Newest drugs used in the treatment of acid-related disorders. lansopraxole (Prevacid) omeprazole (Prilosec) rabeprzole (Acephex) pantoprazole (Protonix) exomepraxole (Nexium)

PPIs

Action: Binds directly to the hydrogen-potassium - ATPase pump mechanism, inhibiting the action of the enzyme which results in a total blockage of hydrogen ion secretion from the parietal cells.

Adverse Effects

Long term use might promote malignant gastric tumors.

Concern about over prescribing resulting in reduction of normal acid-mediated antimicrobial protection.

May need a probiotic when using PPI drug therapy.

Miscellaneous Acid-Controlling Drugs sucralfate (Carafate) Uses: long-term therapy for PUD Action: acts locally binding directly to the

surface of the ulcer. Note: not used as often due to short-term

action and multiple daily dosing.

Cytotec

Generic: misoprostol Action: acts on prostaglandin E analogue Indication: reduces the incidence of gastric

ulcers in patients taking NSAIDs.

Mylicon

Generic: simethicone Action: alters the elasticity of mucus-coated

gas bubbles, causing them to break down into smaller ones

Mylicon

Used to reduce the discomfort of gastric or intestinal gas (flatulence)

Used post-operatively and in post-partum patients to relieve gas pain.

Often used in combination with activated charcoal in oral poisoning (overdose).

Probiotics

Probiotics are live microorganisms (in most cases, bacteria) that are similar to beneficial microorganisms found in the human gut. They are also called "friendly bacteria" or "good bacteria." Probiotics are available to consumers mainly in the form of dietary supplements and foods. They can be used as complementary and alternative medicine.

Probiotics

Probiotics are available in foods and dietary supplements. Examples of foods containing probiotics are yogurt, fermented and unfermented milk, miso, and some juices and soy beverages. In probiotic foods and supplements, the bacteria may have been present originally or added during preparation.

Probiotics

Most probiotics are bacteria similar to those naturally found in people's guts, especially in those of breastfed infants (who have natural protection against many diseases). Most often, the bacteria come from two groups, Lactobacillus or Bifidobacterium. A few common probiotics, such as Saccharomyces boulardii, are yeasts, which are different from bacteria.

Uses

Chronic Diarrhea Irritable Bowel Syndrome Digestive disorders Clients on oral or IV antibiotic therapy Status post abdominal surgery

Antidiarrheals and Laxatives

Chapter 42

Antidiarrheal Drugs

Used to treat diarrhea. Adsorbents Antimotility (anticholenergic and opiates) Intestinal flora modifiers or bacterial replacement

drugs

Adsorbents

Act by coating the walls of the GI tract. Bind with the causative bacteria or toxin to

their adsorbent surface for elimination through the stool.

Pepto-Bismul and Kaoectate

Generic: bismuth subsalicylate Same chemical structure as salicylate

use with caution in children. May cause Reyes Syndrome

Use with caution in clients who are on anti-coagulation therapy.

Pepto-bismol

FDA Warning

The main ingredient, bismuth subsalicylate, has been linked with Reye Syndrome, a potentially life-threatening disorder that has been associated with kids that have viral illnesses, especially the flu and chicken pox, and who take aspirin and other salicylate containing medications, like Pepto-Bismol.

Label advises not to give to children under age 12 years.

Anticholinergics

Used either alone or in combination with other antidiarrheal drugs.

Acts by slowing GI tract motility Atropine hyoscyamine hyoscine

Opiates

Products containing Codeine Nursing consideration: clients on opioids for

post-operative pain control may suffer from constipation.

Atropine: often used to control secretions during surgical procedure – may contribute to post-operative constipation

Imodium A D

Generic name: loperamide Classification: Opiate antidiarrheal Action: inhibits both peristalsis in the intestine

and intestinal secretions, decreasing the number of stools and their water content.

Contraindications: ulcerative colitis, acute diarrhea due to E-coli (Escherichia coli)

Laxatives

Laxative act by: Affecting the consistency of the stool Increasing fecal movement through the colon Facilitating movement through the colon

Constipation

Definition: abnormally infrequent and difficult passage of feces.

Constipation is a symptom not a disease.

Bulk-forming Laxatives

Composed of water-retaining natural and synthetic cellulose derivates. Psylium is an example of natural bulk-forming

laxative. Methylcellulose is an example of a synthetic

cellulose derivative.

Bulk-forming Laxative

Action: increases water absorption, which results in greater bulk of the intestinal contents.

Tend to produce normal, formed stools. Action limited to GI tract so adverse effects

are minimal.

Citrucel (methylcellulose)

Nursing Alert

Have client take with 8 ounces of water. If powdered form needs to be mixed with 8

ounces of water. Fluid must be taken immediately to avoid

swelling of the product in the throat or esophagus or fecal impaction.

Best for clients with chronic constipation.

Emollient laxative

Generic classification: docusate salts Trade names: Colace, Surfak Action: work by lowering the surface tension

of GI fluids; more water and fat are absorbed into the stool and intestine.

Emollients

Uses: post partum postoperative patients Clients on long-term pain control

Outcomes: soft stool with easier defecation

Mineral Oil

Action: eases the passage of stool by lubricating the intestines and preventing water from escaping the stool.

Contraindications Abdominal pain Nausea and vomiting Intestinal obstruction

Hyperosmotic Laxatives

Glycerine Action: promotes bowel movement by

increasing the osmotic pressure in the intestine.

Note: given in the form of a suppository

Stimulant Laxatives

Through the use of natural plant products and synthetic chemical drugs induces intestinal peristalsis.

Note: the stimulant class is the most likely to cause dependence.

Stimulant Laxatives

Generic: senna Trade: Senokot Action: stimulates the GI tract Adverse effects: may cause abdominal pain. Onset of action: complete bowel evacuation

in 6 to 12 hours.

Irritable Bowel Syndrome IBS A condition of chronic intestinal discomfort,

including cramps, diarrhea / or constipation. Two drugs to manage symptoms:

Lotronex (alostron) – approved for women only Zelnorm (tegaserod) – approved for men and

women Action: works on serotonin receptors in the intestinal

tissue.

Antiemetic and Antinausea Drugs

Chapter 52

Chemoreceptor Trigger Zone (CTZ) The area of the brain that is involved in the

sensation of nausea and the action of vomiting.

Vomiting Center (VT)

The area of the brain that is involved in stimulating the physiologic events that lead to nausea and vomiting.

Antiemetic Drugs

Drugs used to relieve nausea and vomiting. All emetic drugs work at some site in the

vomiting pathways.

Syrup of Ipecac

AAP recommendations in 2003 issued an alert to stop the use of this drug to induce vomiting after drug overdose.

Anticholinergic Drugs

Act by binding to and blocking acetylcholine receptors (ACh) in the vestibular nuclei, located deep in the brain.

One drug scopolamine Most commonly used drug for treatment and

prevention of nausea and vomiting associated with motion sickness and postoperatively.

Antihistamines

Action: binds to H1 receptors, potentiate anticholinergic activity.

Most popular OTC medications Generic name: dimenhydrinate Trade name: Dramamine and Benadryl OTC drugs used for motion sickness

Neuroleptics

Action: antidopaminergic, antihistamine and anticholinergic properties.

Trade names: Compazine, Thorazine, Phenergan

Often given as preoperative medication. Used to treat psychotic disorders due to

effect on dopamine.

Compazine: Nursing Alert

Adverse reaction: extrapyramidal reaction--a muscle spasm of the tongue. Other typical adverse extrapyramidal reactions include tremors, drooling, and muscle spasms that usually involve muscles in the shoulders, neck, or eyes.

Antidote: Benadryl

Prokinetics

Metoclopramide Trade name: Reglan Action: promote the movement of substances

through the GI tract and increases motility. Often given in patients getting tube feeding to

promote gastric emptying time.

Serotonin Blockers

Called 5-HT3 receptor blockers because they block the 5-HT3 receptors in the GI tract, CTZ and vomiting centers VC.

Four drugs in this category

ondansetron

Trade name: Zofran is the prototype drug. Approved in 1992. Major break through in treating chemotherapy induced

nausea and vomiting and postoperative nausea and vomiting.

Approved for use in pregnancy.

Side effects from all antiemetics May cause dizziness Caution with use while driving. CNS depression Hypotension

Herbal Therapies

Ginger Root May increase absorption of all oral

mediations, may increase bleeding in clients taking Coumadin and Plavix.