Treatment of nausea and vomiting should be tailored to the cause. There are several medications that work on different neuroreceptors that, when used, can treat nausea and vomiting. For severe cases of vomiting, intravenous fluids may also be needed to treat the accompanying dehydration. [1],[2]

Table 7.7a compares the neurotransmitters involved in the nausea and vomiting process, classes of antiemetic medication targeting these neurotransmitters, prototype antiemetic medications, and associated mechanisms of action.[3] [4][5][6] Each medication class is also discussed in more detail later in this section.

Table 7.7a Neurotransmitters and Associated Medications Used to Treat Nausea and Vomiting
Neurotransmitter Medication Class Antiemetic Drug Mechanism of Action
Acetylcholine (M1) Anticholinergics scopolamine Blocks ACh receptors in vestibular system
Histamine (H1) Antihistamines meclizine Blocks H1 receptors and thus blocks ACh in vestibular system
Dopamine (DA2) Dopamine antagonists prochlorperazine Blocks dopamine in CTZ and may block ACh
Dopamine and ACh (DA2 and M1) Prokinetics metoclopramide Blocks dopamine in CTZ and stimulates ACh in GI tract
Serotonin (5HT) Serotonin antagonists ondansetron Blocks serotonin in GI tract, CTZ, and VC
Substance P (NK1) Neurokinin antagonists aprepitant Inhibits substance P neurokinin receptors
Cannabinoid (CB1) Tetrahydrocannabinols (THC) dronabinol or medical marijuana Activated CB1 receptor leading to inhibitory effects on cerebral cortex

Anticholinergics

Scopolamine is an example of an anticholinergic medication that is often used to treat motion sickness or nausea and vomiting associated with surgical recovery from anesthesia and/or opiate analgesia.

Mechanism of Action

Anticholinergics block ACh receptors in the vestibular center and within the brain to prevent nausea-inducing stimuli to the Chemoreceptor Trigger Zone (CTZ) and the Vomiting Center (VC). They also dry GI secretions and reduce smooth muscle spasms.

Specific Administration Considerations

The scopolamine transdermal patch (see Figure 7.7a)[7] is designed for continuous release of scopolamine following the application to an area of intact skin on the head, behind the ear. The system is formulated to deliver approximately 1 mg of scopolamine to the systemic circulation over 3 days. It is contraindicated in clients with glaucoma. It has been reported to exacerbate psychosis, induce seizures, and cause drowsiness, confusion, and sedation. Due to its anticholinergic properties, scopolamine can decrease gastrointestinal motility and cause urinary retention. Nurses should perform more frequent monitoring during treatment with Transderm Scōp and discontinue Transderm Scōp in clients who develop difficulty in urination. Transderm Scōp contains an aluminized membrane; skin burns have been reported at the application site in clients wearing an aluminized transdermal system during an MRI scan. Remove Transderm Scōp before undergoing an MRI.

A person with a with transdermal patch behind their right ear.
Figure 7.7a Scopolamine Transdermal Patch

Application instructions:

  • Only wear one transdermal system at any time.
  • Do not cut the transdermal system.
  • Apply the transdermal system to the skin in the postauricular area (hairless area behind one ear).
  • After the transdermal system is applied on the dry skin behind the ear, wash hands thoroughly with soap and water and dry hands.
  • If the transdermal system becomes displaced, discard the transdermal system, and apply a new transdermal system on the hairless area behind the other ear.
  • For surgeries other than cesarean section, apply one Transderm Scōp transdermal system the evening before a scheduled surgery. Remove the transdermal system 24 hours following surgery.

Patient Teaching & Education

Transderm Scōp may impair the mental and/or physical abilities required for the performance of hazardous tasks such as driving a motor vehicle, operating machinery, or participating in underwater sports. Concomitant use of other drugs (e.g., alcohol, sedatives, hypnotics, opiates, and anxiolytics) that cause central nervous system (CNS) adverse reactions, or that have anticholinergic properties, may increase this impairment. Inform clients not to operate motor vehicles or other dangerous machinery or participate in underwater sports until they are reasonably certain that Transderm Scōp does not affect them adversely. Scopolamine can cause temporary dilation of the pupils resulting in blurred vision if it comes in contact with the eyes. Advise clients to wash their hands thoroughly with soap and water and dry their hands immediately after handling the transdermal system. Upon removal, fold the used transdermal system in half with the sticky side together, and discard in household trash in a manner that prevents accidental contact or ingestion by children, pets, or others.[8]

Antihistamines

Meclizine is an example of an antihistamine that is often used to treat motion sickness.

Mechanism of Action

Antihistamines block H1 receptors in the vestibular center and may also block acetylcholine (ACh).

Specific Administration Considerations

Antihistamines are contraindicated in clients with glaucoma or an enlarged prostate gland. Dosage should be started one hour before travel begins.

Patient Teaching & Education

  • Do not exceed recommended dosage.
  • Be advised that drowsiness may occur.
  • Avoid alcohol, sedatives, and tranquilizers, which may increase drowsiness.
  • Avoid alcoholic drinks.
  • Be careful when driving a motor vehicle or operating machinery.[9]

Dopamine Antagonists

Prochlorperazine is an example of a dopamine antagonist used to treat nausea and vomiting. It can also be used as an antipsychotic medication.

Mechanism of Action

Prochlorperazine blocks dopamine in the Chemoreceptor Trigger Zone (CTZ). It also calms the central nervous system and may also block acetylcholine.

Specific Administration Considerations

Prochlorperazine can be administered orally, intramuscularly, rectally or intravenously. It is contraindicated in children under age 2 or under 20 pounds. Severe side effects have occurred when used to treat psychosis.

Patient Teaching & Education

Clients should be instructed to take medications as prescribed.  They should avoid alcohol and other CNS depressants. Clients may experience increased photosensitivity and extreme temperatures should be avoided. Clients should be advised that urine may turn pinkish to reddish-brown.[10]

Prokinetics

Metoclopramide is an example of a prokinetic medication (see Figure 7.7b).[11]

Photo of metoclopramide vials, a prokinetic
Figure 7.7b Prokinetics

Mechanism of Action

Metoclopramide blocks dopamine and may also sensitize tissues to acetylcholine. It is used to promote peristalsis to empty the gastrointestinal tract and thus reduce nausea.

Specific Administration Considerations

Metoclopramide can be administered orally, intramuscularly, and intravenously. The onset of pharmacological action of metoclopramide is 1 to 3 minutes following an intravenous dose, 10 to 15 minutes following intramuscular administration, and 30 to 60 minutes following an oral dose. Pharmacological effects persist for 1 to 2 hours.

Metoclopramide should not be used whenever stimulation of gastrointestinal motility might be dangerous (e.g., in the presence of gastrointestinal hemorrhage, mechanical obstruction, or perforation). Metoclopramide is contraindicated in clients with pheochromocytoma because the drug may cause a hypertensive crisis. Metoclopramide should not be used in epileptics or clients receiving other drugs that are likely to cause extrapyramidal reactions because the frequency and severity of seizures or extrapyramidal reactions may be increased. Rare reports of neuromalignant syndrome have occurred.

Patient Teaching & Education

Teach clients to immediately inform the healthcare provider if they experience new feelings of depression or abnormal muscle movements they cannot control such as:

  • lip-smacking, chewing, or puckering of the mouth
  • frowning or scowling
  • sticking out the tongue
  • blinking and moving the eyes
  • shaking of the arms and legs[12]

Serotonin Antagonists

Ondansetron is an example of a serotonin (5HT) antagonist often used to treat severe nausea and vomiting associated with chemotherapy, postoperative nausea and vomiting, and hyperemesis during pregnancy. (See Figure 7.7c for an image of odansetron blocking the 5-HT3 receptor.[13])

Illustration of Ondansetron blocking serotonin receptors.
Figure 7.7c Ondansetron blocking the 5-HT3 receptor

Mechanism of Action

Ondansetron blocks serotonin receptors in the GI tract, the chemoreceptor trigger zone (CTZ), and the vomiting center (VC). See Figures 7.7d and 7.7e for images of the injectable and oral formulations of ondansetron.[14],[15]

Photo of bottle of Zofran injectable.
Figure 7.7d Ondansetron in injectable form
Photo of Zofran tablets
Figure 7.7e Ondansetron in tablet form

Specific Administration Considerations

Ondansetron is available as an orally disintegrating tablet and as an injectable for those clients too nauseated to tolerate oral medication. It is contraindicated with apomorphine. Serotonin syndrome can occur if administered concurrently with other serotonin antagonists or selective serotonin reuptake inhibitors. Ondansetron can cause headaches, drowsiness, constipation, fever, and diarrhea. A rare but serious adverse effect of ondansetron is QT prolongation that can cause an abnormal cardiac rhythm.

Patient Teaching & Education

Teach clients to immediately inform their healthcare provider if they experience a change in heart rate, lightheadedness, or feel faint or have any signs and symptoms of hypersensitivity reactions such as fever, chills, rash, or breathing problems.[16]

Neurokinin Receptor Antagonists

Aprepitant is an example of a neurokinin antagonist used to prevent nausea and vomiting associated with chemotherapy and surgery.

Mechanism of Action

Aprepitant inhibits substance-P neurokinin receptors in the brainstem.

Nursing Considerations

Aprepitant is usually administered concurrently with dexamethasone (a corticosteroid) and ondansetron. It can be administered orally or intravenously. It has clinically significant CYP3A4 drug interactions with medications such as pimozide, diltiazem, and rifampin, and can decrease INR levels when taken concurrently with warfarin. It can also reduce the effectiveness of oral contraceptives.

Patient Teaching & Education

Teach clients taking warfarin that they will need to monitor their INR levels more closely, which may require adjustment of the warfarin dosage while taking aprepitant. Teach clients using an oral contraceptive to use backup birth control.[17]

Tetrahydrocannabinoids (THC)

Dronabinol or medical marijuana is an example of a THC medication used to treat nausea in clients with cancer or AIDS (see Figures 7.7f and 7.7g).[18]

Photo of Marinol capules bottle.
Figure 7.7f Dronabinol, a THC medication

 

Photo of medical marijuana in prescription bottle
Figure 7.7g Medical Marijuana

Mechanism of Action

THC has inhibitory effects in the cerebral cortex causing an alteration in mood and the body’s perception of its surroundings, which may relieve nausea and vomiting, as well as stimulate the appetite.

Specific Administration Considerations

THC will cause a dose-related “high” (easy laughing, elation, and heightened awareness). It is abusable and, thus, is a controlled substance and scheduled medication. THC should be used cautiously in elderly clients because they may be more sensitive to the neurological, psychoactive, and postural hypotensive effects of the drug. In general, dose selection for an elderly client should be cautious, usually starting at the low end of the dosing range.

Patient Teaching & Education

Clients should not drive, operate machinery, or engage in any hazardous activity when using THC. Keep out of reach of children and pets.[19]

Herbal and Vitamin Supplements

Ginger has been used in traditional Indian and Chinese medicine as an antiemetic. Although its mechanism of action is not completely understood, ginger is thought to antagonize the 5HT and cholinergic receptors and may have direct effect on the gastrointestinal tract. Although ginger can cause reflux and heartburn and may potentially cause bleeding because of its anticoagulant effects, dosages of up to 2 g per day in divided doses of 250 mg are considered safe, even in pregnant women. Pyridoxine (vitamin B6) has also been recommended for treating nausea and vomiting in pregnancy. Typical dosages of pyridoxine, 10 to 25 mg every eight hours, cause minimal adverse effects. [20]

Antiemetics Medication Grid

Now let’s take a closer look at the medication grids comparing medications used to treat nausea and vomiting, in Table 7.7a [21].

Medication cards like this are intended to assist students to learn key points about each medication. Because information about medication is constantly changing, nurses should always consult evidence-based resources to review current recommendations before administering specific medication. Basic information related to each class of medication is outlined below. Prototype or generic medication examples are also hyperlinked to a free resource at Daily Med. On the home page, enter the drug name in the search bar to read more about the medication.

Table 7.7 Comparing Medications Used to Treat Nausea and Vomiting [22][23][24][25] scopolamine , meclizine, prochlorperazine, metoclopramide, ondansetron, aprepitant, dronabinol or medical marijuana

Table 7.7 Comparing Medications Used to Treat Nausea and Vomiting
Class Generic Prototype (Brand) Mechanism Indication & Therapeutic Effect Contraindications Side Effects Administration and Nursing Considerations
Anticholinergic Scopolamine

(Hyoscine)

(Transderm)

Inhibits postganglionic muscarinic receptor sites, and acts on smooth muscles that respond to acetylcholine Prevent or reduce N/V associated with motion sickness or surgery

 

Contraindicated in clients with glaucoma anticholinergic effects

Stop if it exacerbates psychosis or causes seizures, cognitive impairment

Apply to hairless skin behind ear for 3 days or the night before surgery and remove 24 hours later

Do not cut patch

After application, thoroughly wash and dry handsRemove before an MRI

Dopamine antagonist prochlorperazine

(Stemetil)

Depresses action on the chemo-receptor trigger zone. Control N/V associated with surgery

 

Use of other CNS depressants

Dementia-related psychosis

Drowsiness, dizziness, amenorrhea, blurred vision, skin reactions, low  Tardive dyskinesia, NMS

 

Can be administered PO, IM, PR, or IV

Not suitable for children under the age of 2

Prokinetic metoclopramide

(Maxeran)

Stimulates upper GI tract

Antagonizes dopamine receptors

GERD

N/V associated with surgery or chemo-therapy

GI hemorrhage

GI obstruction

GI perforation
History of seizures

Restlessness, drowsiness, fatigue, depression, and suicide ideation.

Tardive dyskinesia, NMS

Can be administered PO, IM, and IV

Onset: 1 to 3 mins for IV dose, 10 to 15 mins for IM admin, and 30 to 60 mins for oral dose

Serotonin antagonist ondansetron

(Zofran)

Selective 5-HT3 receptor antagonist. Prevention or treatment of severe N/V associated with surgery, chemo-therapy, or hyperemesis in pregnancy Hypersensitivity Headache, drowsiness, constipation, fever, and diarrhea

May prolong QT
serotonin syndrome if given concurrently with serotonin antagonists or SSRIs

Can be administered as oral disintegrating tablet, PO, or IV
Neurokinin receptor antagonist aprepitant

(Emend)

selective high-affinity antagonist of human substance P/neurokinin 1 (NK1) receptor Prevention of nausea and vomiting associated with chemo-therapy and surgery Clients on pimozide Hypersensitivity reaction, such as hives, rash. and itching; skin peeling or sores; or difficulty in breathing or swallowing Can be administered PO or IV

If on warfarin, increase INR monitoring

If on oral contraceptives, use backup birth control

THC dronabinol or medical marijuana central sympathomimetic activity For treatment of N/V associated with cancer chemo-therapy when other treatment fails Hypersensitivity to sesame oil. Neuropsychiatric Adverse Reactions, Hemodynamic Instability Seizures, Paradoxical Nausea, Vomiting, and Abdominal Pain Administered PO

Dosage may be escalated based on initial results
Use cautiously in elderly client

Clinical Reasoning and Decision-Making Activity 7.7Image of lightbulb in a circle

A nurse is caring for a client who underwent surgery earlier today and is experiencing nausea and vomiting. The original post-op orders included prochlorperazine, but the client continues to experience vomiting despite receiving this medication. The nurse calls the provider and receives a new order for ondansetron orally dissolving tablets, 8 mg three times daily as needed.

  1. How will the nurse assess for symptoms of dehydration?
  2. When administering the medication, the client states, “This tastes terrible! Why can’t I have a normal pill to swallow?” What is the nurse’s best response?
  3. What other measures should the nurse teach the clients to reduce feelings of nausea and avoid dehydration?

Note: Answers to the Critical Thinking activities can be found in the “Answer Key” sections at the end of the book.

 


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  2. Bashashati, M. & McCallum, R. (2014). Neurochemical mechanisms and pharmacologic strategies in managing nausea and vomiting related to cyclic vomiting syndrome and other gastrointestinal disorders. European Journal of Pharmacology, 772, p 79.
  3. Bashashati, M. and McCallum, R. (2014). Neurochemical mechanisms and pharmacologic strategies in managing nausea and vomiting related to cyclic vomiting syndrome and other gastrointestinal disorders. European Journal of Pharmacology, 772, p 79.
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  6. uCentral from Unbound Medicine. https://www.unboundmedicine.com/ucentral
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  8. This work is a derivative of Daily Med by U.S. National Library of Medicine in the public domain.
  9. This work is a derivative of Daily Med by U.S. National Library of Medicine in the public domain.
  10. uCentral from Unbound Medicine. https://www.unboundmedicine.com/ucentral
  11. "Metoclopramide" by John Campbell is licensed under CC0
  12. This work is a derivative of Daily Med by U.S. National Library of Medicine in the public domain.
  13. "Eichelbaum2.jpg" by Michel Eichelbaum is licensed under CC BY-SA 3.0 DE
  14. "000817lg Zofran 8 MG Oral Tablet.jpg" by NLM is licensed under CC0
  15. "Ondansetron (1)" by M is licensed under CC BY-NC 2.0
  16. This work is a derivative of Daily Med by U.S. National Library of Medicine in the public domain.
  17. This work is a derivative of Daily Med by U.S. National Library of Medicine in the public domain.  
  18. "Marinol - Dronabinol" by Steffen Geyer is licensed under CC BY-NC 2.0 & 7.21"Medical Marijuana" by Circe Denyer is licensed under CC0
  19. This work is a derivative of Daily Med by U.S. National Library of Medicine in the public domain.  
  20. Flake, Z., Linn, B., & Hornecker, J. (2015). Practical selection of antiemetics in the ambulatory setting. American Family Physician, 91(5): pp 293-296.
  21. This work is a derivative of Daily Med by U.S. National Library of Medicine in the public domain.
  22. This work is a derivative of  Daily Med by U.S. National Library of Medicine in the public domain.
  23. RNPedia. (2021). https://www.rnpedia.com
  24. OpenMD.Com at openmd.com
  25. uCentral from Unbound Medicine. https://www.unboundmedicine.com/ucentral
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Fundamentals of Nursing Pharmacology - Mohawk College Edition Copyright © 2023 by Chippewa Valley Technical College; Amanda Egert; Kimberly Lee; and Manu Gill is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.

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