Download Antiemetics: Easing Patients` Suffering

PHARMACOLOGY UPDATE
Antiemetics: Easing Patients’ Suffering
Cheryl Lehman, PhD RN CRRN-A
Nausea and vomiting makes patients
uncomfortable, miserable, and inhibits healing.
Antiemetics are often used to ease patients’
suffering, so they can eat, drink, and progress.
This column will review some of the more
commonly used medications for nausea and
vomiting, and will point out a few precautions
to take as you administer these drugs.
Conditions or treatments commonly
associated with nausea and vomiting include
chemotherapy, recovery from general
anesthesia, pregnancy, and motion sickness.
Other causes include vertigo, vestibular
neuronitis, acute labrynthitis, MI, intraabdominal inflammation, gastrointestinal (GI)
obstruction, medication, food allergies, toxin or
environmental exposure, alcohol intake, high
altitude sickness, infection, DKA, alcoholic
ketoacidosis, acute adrenal insufficiency,
intestinal endometriosis, CNS pathology,
hypercalcemia, and psychogenic origin.
It is important to assess the duration of
the nausea and vomiting, and to differentiate
acute from chronic symptoms. Acute nausea
and vomiting may have need for immediate
intervention due to consequences such as
dehydration. Lightheadedness, chest pain,
abdominal pain, cough and /or hematemesis
accompanying nausea and vomiting require
an immediate in-depth assessment to rule out
an emergent condition and to determine the
need for immediate therapeutic intervention to
correct the consequences of vomiting.
There are several drugs used to treat nausea
and vomiting. Many, if not most, are not
approved for use in pregnancy.
Dopamine antagonists
These medications (See Table 1) act to block
dopamine receptors in the brain, limiting input
to the medullary vomiting center. Most of these
medications have extensive side effects.
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Table 1. Dopamine Antagonists
Medication
Indications/Comments
Precautions
Prochlorperazine (Compazine®)
Moderate to severe nausea and vomiting Do not use with CNS depressants
Half life = 7 hours. Dopamine receptor
including alcohol. Side effects include
antagonist. PO or IV.
hypotension and antidopaminergic
effects such as dystonia and dyskinesia. Extrapyramidal side effects
related to duration and cumulative dose.
Neuroleptic malignant syndrome can
occur.
Promethazine (Phenergan®)
Prevention and control of nausea and
vomiting associated with anesthesia;
active and prophylactic treatment of
motion sickness. PO, IM, IV
Side effects include drowsiness. May
lower seizure threshold. Avoid use with
alcohol and other CNS depressants.
CAUTION with IV administration – this
vesicant can cause severe tissue damage.
Chlorpromazine (Thorazine®)
For nausea and vomiting.
Side effects include extrapyramidal
reactions and neuroleptic malignant
syndrome.
Note. One other dopamine antagonist used for nausea and vomiting is droperidol (Inapsine®) which has a risk of sudden cardiac
death.
Table 2. Antihistamines
Medication
Indications/Comments
Precautions
Meclizine (Antivert®, Dramamine II®)
For nausea, vomiting and dizziness associated with motion sickness. Also used to
treat vertigo associated with vestibular
system disturbances.
Drowsiness, dizziness, tinnitus, insomnia,
incoordination, fatigue, tremors. Avoid
use with alcohol. Use with caution with
asthma, glaucoma, and prostate gland
enlargement (anticholinergic actions).
Use with caution in older adults, may
cause confusion, constipation, urinary
retention and increase fall risk. Use with
caution in patients with liver disease and
narrow angle glaucoma. Do not use if
breastfeeding.
Diphenhydramine (Benadryl®)
Used for motion sickness.
Sedation. Caution with narrow angle
glaucoma, the elderly, stenosing peptic
ulcer, and symptomatic prostatic hypertrophy. Additive effects with alcohol and
CNS depressants.
Note. Other antihistamines used as antiemetics include buclizine (Bucladin-S®), cyclizine (Marezine®), and dimenhydrinate
(Dramamine®).
Antihistamines
These drugs (See Table 2) work at the level of
the vestibular afferents and in the brain stem.
They inhibit the action of histamine at the H1
receptor, and appear to dull how the inner ear
senses motion. Their use is limited mainly to
motion sickness and post-op emesis.
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Antiemetics: Easing Patients’ Suffering
Prokinetic agents
These are used to improve GI motility
(See Table 3).
Anticholinergics
These inhibit the action of acetylcholine at
the muscarinic receptor, and limit stimulation of
the vomiting center from the vestibular system
(See Table 4). Used for motion sickness, postop
nausea and vomiting, and the management of
intractable retching, nausea, emesis, and pain
associated with intestinal obstruction.
Continued from page 3
Table 3. Prokinetic Agents
Medication
Indications/Comments
Precautions
Bethanechol (Urecholine®)
Cholinergic agent used to enhance contractions in the GI tract. Also stimulates
saliva and gastric acid production.
Abdominal cramps, diarrhea,
salivation, flushing, bradycardia, blurred
vision.
Trimethobenzamide (Tigan®)
To treat nausea and vomiting by promoting GI tract motility and increasing
antroduodenal coordination.
Drowsiness, transient increase in
stool frequency.
Metoclopramide (Reglan®)
Dopamine receptor antagonist. PO or IV
Incidence of side effects is 10%–20%
and includes anxiety, restlessness,
depression, confusion, insomnia,
hallucinations, fatigues, and
extrapyramidal effects.
Medication
Indications/Comments
Precautions
Scopolamine (Transderm Scop®)
Medication delivery through transdermal patch, changed every three days.
Use with caution in the elderly and in
patients with pyloric or urinary bladder
neck obstruction, and in those with
intestinal obstruction. Side effects
include dry mouth, drowsiness, urinary
retention, blurred vision, and dilated
pupils.
Serotonin receptor antagonists
This class of medication is effective for use
with chemotherapy-induced emesis, radiationinduced emesis, GI motility disturbances,
carcinoid syndrome, migraine related nausea
and vomiting, and anxiety (See Table 5). This
class has become the primary treatment for a
number of causes of nausea. These are usually
given as a one-time dose before chemotherapy
is given. They are usually given with adjunct
corticosteroid.
Other
Other medications (See Table 6) that have been
reported to have a potential role in controlling
nausea and vomiting in varying conditions
include corticosteroids, megestrol acetate,
haloperidol, tetrahydrocannabinol, benzodiazepines, tricyclic antidepressants, ginger, and
neurokinin-1 antagonists.
Suggested Reading
Flake, Z.A, Scalley, R.D., & Bailey, A.G. (2004). Practical
Selection of Antiemetics. American Family
Physician, 69 (5), Retrieved online 10/31/2006.
Gralla, R.J., Osoba, D., Kris, M.G., Kirkbride, P., Hesketh,
P.J., Chinnery, L.W., et al. (1999). Recommendations
for the use of antiemetic: Evidence-based, clinical
practice guidelines. Journal of Clinical Oncology,
17(9), 2971–2994.
Institute for Safe Medical Practices. (2006). Action needed
to prevent severe tissue injury with IV promethazine.
Medication Safety Alert. Retrieved Oct. 31, 2006
from www.ismp.org/Newsletters/acutecare/archives/
Aug06.asp.
CLASSIFIED
Table 4. Anticholinergics
Table 5. Serotonin Receptor Antagonists
Medication
Indications/Comments
Precautions
Ondansetron (Zofran®)
Effective in control of chemo-induced
emesis.
Not effective with motion sickness. Side
effects include constipation and headache as well as QT prolongation, QRS
widening, and hypersensitivity reactions.
Dolasetron (Anzemet®)
As above
As above
Granisetron (Kytril®
As above
As above
Tropisetron (Navoban®)
As above
As above
Medication
Indications/Comments
Precautions
Bismuth subsalicylate
Reduces nausea by coating the stomach
lining
Pepto-bismol® contains aspirin: caution
with use in children who may have flu or
chicken pox due to a higher risk of Reye’s
Syndrome. Do not administer if patient
allergic to aspirin or salicylates. Caution
if used with anticoagulants, gout medications, arthritis medications, diabetes
medications. May cause tongue or stool
to turn dark.
Table 6. Other Medications
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