Pharmacology - Chapter 47 also ATI Chapter 29

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Drugs for Gastrointestinal Tract Disorders

adsorbents

Act by coating the wall of the GI tract and adsorbing bacteria or toxins that cause diarrhea. Includes kaolin and pectin. Activated charcoal, Pepto-Bismol, Kaopectate

antidiarrheals

Relieve or control the symptoms of acute or chronic diarrhea. Include (1) opiates and opiate related agents, (2) somastatin analogue, (3) adsorbents, and (4) miscellaneous antidiarrheals.

antiemetics

Medications used to stop vomiting. Frequently used to prevent motion sickness, and for side effects of anticancer (antineoplastics) agents, radiation, and toxins

cannabinoids

Active ingredients in marijuana, were approved for clinical use in 1985 to alleviate nausea and vomiting resulting from cancer treatment.

cathartics

Used to eliminate fecal matter. Results in a soft to watery stool with some cramping. Dosage determines whether it is a laxative or a cathartic

chemoreceptor trigger zone (CTZ)

Lies near the medulla and is the area of the brain that is involved in the sensation of nausea and the action of vomiting.

constipation

Accumulation of hard fecal matter in the large intestine

diarrhea

Frequent liquid stool

emetics

Drugs used to induce vomiting

emollients

Lubricants and stool softeners (surface-acting or wetting drugs) used to prevent constipation. Decreases straining during defecation.

laxatives

Used to eliminate fecal matter. Promotes a soft stool. Dosage determines whether it is a laxative or a cathartic

opiates

Decreases intestinal motility, thereby decreasing peristalsis.

osmotics

Hyperosmolar laxatives which include sals or saline products, lactulose, and glycerin.

purgatives

Harsh cathatics that cause a watery stool with abdominal cramping

selective chloride channel activators

New category of laxatives used to treat idiopathic constipation in adults. Activates chloride channels in the lining of the small intestine, leading to an increase in intestinal fluid secretion and motility.

vomiting center

Cause vomiting when stimulated. Located in the medulla oblongata; recieves and propagates impulses to the upper GI tract organs, diaphragm, and abdominal muscles.

Gastrointestinal disorders

Vomiting - diaphragm & GI
Vomiting Center (VC)
Chemoreceptor trigger zone (CTZ)
Toxic substance ingestion
Diarrhea
Constipation

Antiemetics - Nonpharmacologic measures

Weak tea - dilute with water
Gatorade
Crackers - no butter
Toast - no butter
Ginger Ale, Sierra Mist -room temp, make it flat (shake out bubbles)

Nonprescription antiemetics -Antihistamines
Dimenhydrinate (Dramamine) - Motion sickness
Diphenhydramine (Benadryl) - Allergies

Side effects (similar to anticholinergics)
Drowsiness
Dry mouth
Constipation - urinary retention

Nonprescription antiemetics - Bismuth subsalicylate (Pepto-Bismol) - for indigestion

Action
Acts directly on gastric mucosa to suppress vomiting

Antiemetics -Prescriptive antihistamines
Hydroxyzine (Vistaril) - anti-hypnotic (has additivie effect w/Benadryl)
- Promethazine (Phenergan) - comes in suppository form

Acts on vomiting center (VC), decreases stimulation of CTZ

Antiemetics - Anticholinergic

Scopolamine (Transderm-Scop)
Acts on VC, decreases stimulation of CTZ

Antiemetics - Dopamine antagonists

Phenothiazines
Promethazine (Phenergan)

Antiemetics - Promethazine (Phenergan)

Action
Inhibit CTZ, blocks H1 receptor sites
Side effects
Drowsiness (sedative)
dry mouth, blurred vision, tachycardia, constipation, urinary retention, photosensitivity,
- EPS - extrapyramidal syndrome includes:
--- tardive dyskinesia - Involuntary repetitive movement
--- acute dystonia - sudden spasms (face,neck,back, limbs)
--- akathisia - inner restlessness

Antiemetics - Dopamine antagonists

Butyrophenones
Haloperidol (Haldol) - can be anti-hypnotic -called vitamin H
Droperidol (Inapsine)
Action
Blocks dopamine (D2) receptors in CTZ
Side effects
EPS, hypotension
Metoclopramide (Reglan) works for nausea, open heart or GI surgery - delays gastric emptying
Action
Blocks D2 receptors in CTZ
Side effects
Sedation, diarrhea, EPS

Antiemetics - Benzodiazepines - suffix -PAMs and -LAMs
Lorazepam (Ativan) - also called "Vitamin A"

Use
Cancer chemotherapy - used as a premed to avoid nausea
Used in combination with a glucocorticoid and serotonin 5-HT3 receptor antagonist

Antiemetics - Serotonin receptor antagonist
Ondansetron (Zofran) - ODT under the tongue
comes in foil package

Action
Blocks serotonin receptors in CTZ and afferent vagal nerve terminals in UGI
Use
Cancer chemotherapy - to pretreat for nausea
Side effects
Headache, diarrhea, dizziness, fatigue

Antiemetics - Glucocorticoids
Dexamethasone (Decadron) - spinal/cerebral injury
Methylprednisolone (Solu-Medrol) - COPDers

Use: cancer chemotherapy - used as a premed

Antiemetics - Cannabinoids - 1st approved medical marujuana
Dronabinol (Marinol)

Store in a refrigerator - Small white oval pill (like a tic-tac)
Side effects
Drowsiness, dizziness, dry mouth, impaired thinking, euphoria, mood changes, headaches, confusion, depersonalization, nightmares, incoordination, memory lapse, anxiety

Antiemetics - Miscellaneous
Diphenidol (Vontrol)
Trimethobenzamide (Tigan)

Action
Suppress impulses to CTZ
Side effects
Drowsiness, dry mouth, tachycardia, urine retention, constipation, diarrhea, blurred vision, hypotension, EPS

Antiemetics - Nursing interventions

Provide mouth care
Monitor vital signs, bowel sounds
Monitor for dehydration
Warn not to consume alcohol when taking an antiemetic as it depresses the CNS
Warn pregnant females to avoid antiemetics drug of choice is Zofran ODT with a Pregnancy caregory B
Avoid driving motor vehicles - causes drowsiness

Emetics - Ipecac (OTC)

- Action
---- Stimulates CTZ & acts directly on gastric mucosa
- Use
---- Induces vomiting after toxic substance
- Caution
---- Avoid vomiting if substance is caustic or petroleum
---- If vomiting contraindicated, activated charcoal is given
- Administration
---- Use ipecac syrup, not ipecac fluid extract
---- Take with a glass of water or fluid, not with milk or carbonated beverage
---- Vomiting occurs in 15 to 30 minutes (lavage likely if nothing after 15 minutes)
---- If vomiting does not occur, give activated charcoal (absorbs toxins) - It is black as grill charcoal, clothing warning
---- Gastric lavage may be needed if vomiting does not occur

Diarrhea -Causes
Diarrhea defined as 3 or more episodes per day

Spicy or spoiled foods
Bacteria (Escherichia coli)
virus
toxins
Drug reactions
Fecal impaction
laxative abuse
Malabsorption disorders
bowel tumor
inflammatory bowel disease (IBS)
Stress, anxiety

Antidiarrheals - Opiates - NO MORE than two days

Purpose
Decrease hypermotility
Caution
Should not be used for more than 2 days or if fever is present
Types
Opiates and opiate-related agents (NO MORE THAN TWO DAYS)
Somatostatin analog
Adsorbents

Antidiarrheals - Opiates and opiate-related agents
Paregoric (camporated opium tincture)
Diphenoxylate with atropine (Lomotil)
Loperamide (Imodium)

Kept in a locked drawer - controlled substance
Opiates decrease GI motility this is why they work
Opiates may cause respiratory depression
Especially children and elderly
May cause physical dependence
Atropine contraindicated in glaucoma
WATCH FOR pernicious anemia

Antidiarrheals - Somatostatin analog
Octreotide (Sandostatin) - used with cancer PTs

Use: for severe diarrhea from cancer

Antidiarrheals - Adsorbents
Bismuth salts (Pepto-Bismol)
Kaolin-pectin (Kaopectate)

Action: coats GI tract, absorbs bacteria or toxins

Antidiarrheals - Combination agents
Parepectolin (paregoric, Kaolin-pectin)

...

Antidiarrheals - Nursing interventions

Monitor BP, Respirations
Report more than 10-15 mmHg decrease in BP - HYPOTENSION
Monitor frequency of bowel movements and bowel sounds
Assess for evidence of dehydration
Monitor electrolytes
Avoid fried foods, milk, and sedatives
If diarrhea persists after 48 hrs, notify MD

Constipation

Causes
Bowel obstruction, fecal impaction _Good for MS patients
Chronic laxative use, ignoring urge to defecate
Neurologic disorders
Side effect of drugs
Lack of exercise, fiber, water

Laxatives
Laxatives: promote soft stool
Cathartics: soft to watery stool with cramping
Purgatives: watery stool with cramping

Types of laxatives
Osmotic (saline)
Stimulant (irritants)
Bulk-forming
Emollient (stool softeners)

Contraindications
Undiagnosed abdominal pain
Inflammatory disorders of the GI tract
Appendicitis (9-10 times stool is the cause of appendicitis), diverticulitis, ulcerative colitis
Spastic colon
Bowel obstruction
Pregnancy - Benefits outweigh risk when there is a risk of early delivery

Osmotic (Saline) Laxatives
Polyethylene glycol (GoLYTELY) - preps for colonoscopy
Lactulose (Chronulac) - monitor liver failure (cirrhosis)
High ammonia - confusion
encephalopathy

Action
Hyperosmolar salts pull water into colon, increase water in feces to increase bulk, which stimulates peristalsis
Side effects
Fluid and electrolyte imbalances, hypotension, weakness

Stimulant (Irritant) Laxatives
Phenolphthalein (Ex-Lax, Correctol) reddish brown color urine is mistaken for hematuria
Bisacodyl (Dulcolax)

Action
Increase peristalsis by irritating sensory nerve endings in intestinal mucosa
Results: orally 6-12 hrs, supp 15-60 min
Side effects
Abdominal cramps, weakness, reddish brown urine, diarrhea

Bulk-Forming Laxatives - Mix with water or juice
Psyllium hydrophilic mucilloid (Metamucil)
Calcium polycarbophil (Fiber-Con)

Action
Absorb water into intestines, increase bulk and peristalsis
Results
8-12 hrs

Administration
Mix in glass of water or juice, stir, drink immediately, follow with 1 glass water

Side effects
Abdominal cramps
Excess laxative
Nausea,vomiting, gas, diarrhea

Emollients (Stool Softeners)
Docusate (Colace)

Action
Lowers surface tension
Promotes water accumulation in intestine
Emulsifies and lubricates feces for easier passage

Use
Prevents constipation
Reduces straining post surgery or myocardial infarction use with fresh CABG patients, MI, CAD (no vagal)

Side effects
Abdominal cramping, nausea, vomiting, diarrhea

Q: A client complains of constipation and requires a laxative. The nurse reviews a common cause of constipation which includes?

A: Lack of Exercise

Q: A client has nausea and is taking andansetron (Zofran). The nurse explains that the action of this drug is what?

A: Block seratonin receptors in the CTZ

Q: A client who has constipation is prescribed a bisacodyl suppository. The nurse explains that bisacodyl does what?

A: Acts on smooth intestinal muscle to increase bulk and peristalsis.

Q: A client is using the scopalimine patch to prevent motion sickness. The nurse teaches the client that which is a common side effect of this drug?

A: Dry mouth

Q: When metoclopramide (Reglan) is given for nausea, the client is cautioned to avoid which substance?

A: Alcohol

Q: The nurse is administering opium tincture (paregoric) to a client. What five items should be included in the teaching regarding this medication?

1. Warn the client to avoid laxative abuse
2. Record the frequency of bowel movements
3. Encourage the client to increase fluid intake
4. Intruct avoiding this drug if the client has narrow angle glaucoma
5. Warn the client against taking sedatives concurrently.

Q: For what three conditions would a laxative be indicated?

A: (1) A young adult female who is postpartum following a vaginal delivery with an episiotomy
(2) A young adult client affected by IBS
(3) An older adult client preparing for a colonoscopy

Q: Children and older adults are usually not administered prochlorperazine (Compazine) for nausea and vomiting due to risk for which effect?

A: Extrapyrimidal symptoms such as restlessness, anxiety, and spasms of the face and neck

Q: Laxatives containing sodium are contraindicated for which of the following client conditions?

A: Hypertension

Q: A nurse is taking a history on a client with IBS and constipation. Which item in the client's history is a contraindication to lubiprostone ( Amitizal)?

A: Ulcerative colitis

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