1. Chapter 26 Drugs used to treat nausea, vomiting, constipation, and diarrhea

2. Nausea and Vomiting
nausea: sensation of abdominal discomfort that may lead to the urge or need to vomit
vomiting (emesis): expelling stomach contents through the mouth, signals illness or injury
vomitus (emesis) is the food and fluid expelled from the stomach through the mouth
nausea may occur without vomiting and vice versa
often nausea and vomiting occur together
retching: involuntary, labored, spasmodic contractions of the abdominal and respiratory muscles without vomitus, aka “dry heaves”

3. Structures Involved in Vomiting (box 26-1)
vomiting center (VC) is located in medulla, it coordinates the vomiting reflex
nerves from sensory receptors in the pharynx, stomach, intestines and other tissues connect directly with the VC through the vagus and splanchnic nerves. Nerves produce vomiting when stimulated
VC also responds to stimuli from other tissues-cerebral cortex, vestibular apparatus of inner ear, and blood
stimuli travel to the chemo-receptor trigger zone in the medulla, activates the VC to induce vomiting
when VC is stimulated nerve impulses are sent to salivary, vaso- motor and respiratory centers
reflex begins with sudden, deep inspiration that increases abdominal pressure, abdominal muscles contract
soft palate rises and the epiglottis closes, this prevents aspiration of vomitus into lungs
pyloric sphincter contracts and cardiac sphincter and esophagus relax, stomach contents are expelled. Saliva increases to aid expulsion
pallor, sweating and tachycardia also occur with vomiting

4. Common Causes of Nausea and Vomiting box (26-2)
chemotherapy
drug therapy
emotional disturbances
GI disorders (gastritis, liver, gallbladder, pancreatic diseases)
infection
mental illness
motion sickness
over-eating
pain
pregnancy
radiation therapy
stomach irritation by certain foods/liquids
surgical procedures
unpleasant sights/odors

5. constipation: passage of hard, dry stool
person usually strains to have a bowel movement
stools are large or marble-size
large stools cause pain as they pass through anus
constipation occurs when feces move slowly through the bowel, this allows more time for water absorption
common causes of constipation:
low-fiber diet
ignoring urge to defecate
decreased fluid intake
inactivity
drugs
aging
certain diseases

6. if not relieved constipation can lead to fecal impaction
constipation cont….
dietary changes, fluids, and activity prevent or relieve constipation, so do drugs and enemas
if not relieved constipation can lead to fecal impaction
fecal impaction: prolonged retention and build-up of feces in rectum
feces are hard or putty-like, person cannot defecate, more water is absorbed from the already hard feces
liquid feces pass around hardened fecal mass in the rectum, the liquid feces seep from the anus

7. Diarrhea:
diarrhea: frequent passage of liquid stools, move through intestines rapidly, reduces time for liquid absorption
abdominal cramping, nausea and vomiting may occur
causes: infections, drugs, irritating foods, microbes in food and water
diet and drugs are ordered to reduce peristalsis
fluid lost through diarrhea needs to be replaced, otherwise dehydration occurs
person has pale or flushed skin, dry skin, and a coated tongue
urine is dark and scant in amount (oliguria)

8. thirst, weakness, dizziness and confusion also occur
diarrhea cont…
thirst, weakness, dizziness and confusion also occur
falling blood pressure and increased pulse and respirations are serious signs
death can occur
nursing process focuses on meeting persons fluid needs
microbes can cause diarrhea, preventing spread of infection is important (follow standard precautions)

9. Focus On Older Persons Drugs Used to Treat Nausea, Vomiting, Constipation and Diarrhea Older persons are at risk for dehydration from diarrhea. the amount of body water decreases with aging. Many diseases common in older persons affect body fluids. So do many drugs. Report signs of diarrhea at once. Ask the nurse to observe the stool. Death is a risk when dehydration is not recognized and treated

10. Delegation Guidelines
Drugs Used to Treat Nausea, Vomiting, Constipation and Diarrhea:
Some drugs used to treat nausea, vomiting, constipation and diarrhea are given parenterally- by intramuscular or intravenous injection. Because you do NOT give parenteral dose forms, they are NOT included in this chapter. Should a nurse delegate the administration of such to you, you must:
- remember that parenteral dosages are often very different from dosages other routes
-Refuse the delegation. Make sure to explain why. Do NOT just ignore the request. Make sure the nurse knows that you cannot give drug and why

11. Drug Therapy for Nausea and Vomiting
control of vomiting is important to:
relieve the distress caused by vomiting
prevent aspiration of stomach contents into lungs
prevent dehydration
prevent electrolyte imbalance
treatment is directed at the cause (box 26-2)
treatment may involve non-drug measures and drugs
anti-emetics are drugs used to treat nausea/vomiting, generally more effective if given before onset of nausea
most anti-emetics do one of the following:
suppress action of the vomiting center
inhibit impulses going to or from the VC

12. Dopamine Antagonists:
Drug Therapy for Nausea and Vomiting
Dopamine Antagonists:
inhibits dopamine receptors that are part of pathway to VC, dopamine receptors in other parts of brain are blocked too
drugs in this class are phenothiazines, used for mild-moderate nausea and vomiting associated with:
anesthesia
surgery
radiation therapy
chemotherapy
Butyrophenones: used as anti-emetics in surgery and chemo, sedation is a side-effect
metoclopramide (Reglan): also acts on receptors in GI tract, useful for persons with GI cancers, gastritis, peptic ulcer, radiation sickness and migraines

13. Assisting With the Nursing Process dopamine antagonists:
Drug Therapy for Nausea and Vomiting cont…
Assisting With the Nursing Process
dopamine antagonists:
ASSESSMENT: observe type, amount and frequency of emesis, observe persons level of alertness
PLANNING: see table 26-1 (pg ) “Dose Forms”
IMPLEMENTATION: see table 26-1 (pg ) for “Adult Dosage Range
EVALUATION:
-see ch. 15 for phenothiazines
-see ch. 15 for haloperidol
-see ch. 25 formetoclopramide (Reglan)

14. Assisting With the Nursing Process serotonin antagonists:
Drug Therapy for Nausea and Vomiting cont…
Serotonin Antagonists:
block receptors in medulla and GI tract that cause nausea and vomiting
used to treat emesis associated with: chemo, radiation and post-operative nausea/vomiting
Assisting With the Nursing Process
serotonin antagonists:
ASSESSMENT: observe type, amount and frequency of emesis, observe persons level of alertness
PLANNING: see table 26-1 (pg ) “Dose Forms”
IMPLEMENTATION: see table 26-1 (pg ) for “Adult Dosage Range
EVALUATION:
-headache, diarrhea, constipation: usually mild
-sedation: provide for safety

15. Assisting With the Nursing Process Anti-Cholinergic Agents :
Drug Therapy for Nausea and Vomiting cont…
Anti-Cholinergic Agents:
motion sickness likely results from stimulation of structures in the inner ear
stimuli are transmitted to areas near VC
excess acetylcholine is present
these drugs are used to counter-balance the excessive amounts of acetylcholine present
Assisting With the Nursing Process
Anti-Cholinergic Agents :
ASSESSMENT: observe type, amount and frequency of emesis, observe persons level of alertness
PLANNING: see table 26-1 (pg ) “Dose Forms”
IMPLEMENTATION: see table 26-1 (pg ) for “Adult Dosage Range
EVALUATION: see Ch. 14

16. Assisting With the Nursing Process
Drug Therapy for Nausea and Vomiting cont…
Cortico-Steroids:
used for nausea and vomiting, are effective alone or when used with other anti-emetics, may help the person accept and control emesis
Assisting With the Nursing Process
ASSESSMENT: observe type, amount and frequency of emesis, observe persons level of alertness
PLANNING: see table 26-1 (pg ) “Dose Forms”
IMPLEMENTATION: see table 26-1 (pg ) for “Adult Dosage Range
EVALUATION: side effects do not occur often

17. Assisting With the Nursing Process
Drug Therapy for Nausea and Vomiting cont…
Benzodiazepines:
act as anti-emetics through a combination of effects, they do the following
cause sedation, reduce anxiety, depress VC, have an amnesia effect
effective in reducing frequency of nausea/vomiting
Assisting With the Nursing Process
Benzodiazepines :
ASSESSMENT: observe type, amount and frequency of emesis, observe persons level of alertness
PLANNING: see table 26-1 (pg ) “Dose Forms”
IMPLEMENTATION: see table 26-1 (pg ) for “Adult Dosage Range
EVALUATION: see ch 15

18. Assisting With the Nursing Process
Drug Therapy for Nausea and Vomiting cont…
Neurokinin-1 Receptor Inhibitor:
act as anti-emetics used to prevent nausea/vomiting from chemo and anesthesia
aprepitant (Emend): drug blocks actions of substances that cause nausea/vomiting, used with cortico-steroid and a serotonin agonist
Assisting With the Nursing Process
aprepitant (Emend):
ASSESSMENT: observe type, amount and frequency of emesis
PLANNING: see table 26-1 (pg ) “Dose Forms”
IMPLEMENTATION: see table 26-1 (pg ) for “Adult Dosage Range
EVALUATION: report and record:
-Tiredness, nausea, hiccups, constipation, diarrhea, loss of appetite, headache, hair loss. Drug is taken for up to 3 days, minimal side effects

19. Drug Therapy for Constipation and Diarrhea
laxatives: substances that cause evacuation of the bowel
anti-diarrheals: drugs that relieve symptoms of diarrhea

20. Laxatives: types of laxatives:
stimulant laxatives: act directly on intestine, cause irritation that promotes peristalsis and evacuation, both oral (acts in 6-10 hours) and rectal (acts in mins) agents
saline laxatives: draw water into intestine from surrounding tissues, extra water affects stool consistency and distends the bowel, peristalsis increases. Usually agents act in 1-3 hours
Lubricant laxatives: contain oils, they lubricate intestinal wall and soften feces. Allows smooth passage of feces, onset is usually 6-8 hours, may be up to 48 hours. Peristalsis does NOT appear to increase, useful to prevent constipation in persons who should not strain during defecation
bulk-producing laxatives: given with a full glass of water, drug causes water to be retained in feces, increasing the bulk. Increased bulk stimulates peristalsis, onset usually hours

21. Types of laxatives cont….
Fecal softeners: draw water into feces which softens it, these do NOT stimulate peristalsis. May take 72 hours for a soft bowel movement. These are often call stool softeners, used to prevent constipation/straining
Bulk forming laxatives: soften and increase fecal mass, used to control certain types of diarrhea by absorbing the irritating substance. Substance is then removed from the bowel with defecation. Agents dispersed into water or juice
Stimulant and saline laxatives: combo of stimulant and saline laxatives, used to relieve acute constipation. Usually used as a bowel prep to remove gas and feces before x-rays of examined kidneys, intestine or gallbladder
Goals of laxatives are:
Relief from abdominal discomfort
Passage of bowel contents within a few hours of administration

22. Assisting With the Nursing Process
laxatives:
ASSESSMENT: ask about the persons bowel elimination patterns, ask person to describe any abdominal pain
PLANNING: see table 26-2(pg. 333)
IMPLEMENTATION: follow directions on MAR and container, give adequate water with bulk-forming agents. Without enough water, they can cause esophageal, gastric, intestinal, or rectal obstruction
EVALUATION: report and record:
-Griping (gripping), abdominal discomfort. Griping: sever and spasm-like pain the abdomen caused by an intestinal disorder. Can result from excessive bowel stimulation
-abdominal tenderness, pain, bleeding, vomiting, diarrhea, abdominal distention. No bowel movement or only a small stool may signal impaction, or may signal an acute abdomen. This is serious and could require surgery

23. Anti-Diarrheal Agents: 2 types of anti-diarrheal agents are:
local acting agents: absorb excess water to cause a formed stool, absorb irritants or bacteria causing the diarrhea
systemic agents: act through nervous system to reduce peristalsis and GI motility
anti-diarrheal drugs usually ordered:
when diarrhea is of sudden onset
has lasted 2-3 days and is causing significant fluid loss
when persons with inflammatory bowel disease develop diarrhea
post-op for diarrhea after GI surgery
goal of therapy is relief from diarrhea and its discomforts

24. Assisting With the Nursing Process
Anti-diarrheal:
ASSESSMENT: ask about the persons bowel elimination patterns, ask person to describe any abdominal pain
PLANNING: see table 26-3(pg ) for “Oral Dose Forms”
IMPLEMENTATION: see table 26-3(pg ) “Adult Dosage”
follow directions on MAR and container, give adequate water with bulk-forming agents. Without enough water, they can cause esophageal, gastric, intestinal, or rectal obstruction
EVALUATION: report and record:
-abdominal discomfort, nausea, constipation. These may result from the excessive use of local agents
-prolonged or worsening diarrhea, toxins may be present