Ondansetron is a highly potent antiemetic drug that works by blocking serotonin receptors. It is effective in preventing nausea and vomiting from chemotherapy, radiation, gastroenteritis, and post-operatively. Common side effects include headache, diarrhea, and constipation. Ondansetron is metabolized in the liver by cytochrome P450 enzymes and can have drug interactions with inducers or inhibitors of these enzymes. It is generally well-tolerated but rare serious side effects like blindness have been reported. Ondansetron requires careful use with serotonergic drugs due to risk of serotonin syndrome.

1. Joanne Gay Dishman School of Nursing
Maan, Fall 2016
Advanced Pharmacology

2. • Brand Name: Zofran, Zofran ODT, Zuplenz,
Emeset,Emetron,Emodan,Ondemet,Setronax,Ondavell
• Functional class: Antiemetic
• Chemical Class: 5-Hydroxytryptamine type 3 receptor antagonist
• Pregnancy Category: B
Ondansetron Hydrochloride

3. • Acute gastroenteritis is the most common cause of emergency room,
physician visits, and hospitalization in infants and young children (Cheng,
2011, Elliott, 2007). Ondansetron is a highly potent antiemetic drug that is
effective in preventing chemotherapy and radiation-induced nausea and
vomiting with a very low risk of adverse effects. Recently, ondansetron has
been used to control vomiting related to acute gastroenteritis (Cheng, 2011).

4. • Ondansetron is a serotonin 5-HT3 receptor antagonist used mainly as an
antiemetic to treat nausea and vomiting, often following chemotherapy. Its
effects are thought to be on both peripheral and central nerves. It reduces the
activity of the vagus nerve, which deactivates the vomiting center in the medulla
oblongata, and also blocks serotonin receptors in the chemoreceptor trigger
zone.
Pathophysiological Condition Treated

5. Vomiting Center

6. Ondansetron is a highly potent and selective serotonin 5-HT3 receptor antagonist.
The ondansetron is the most widely used drug to prevent postoperative nausea and
vomiting or chemotherapy-induced nausea and vomiting and acute gastroenteritis in
children (Cheng, 2011, Becker, 2010).
Intended Drug Response

7. Drug Interactions
Drugs Affecting Cytochrome P-450 Enzymes
Ondansetron is metabolized by hepatic cytochrome P-450 drug-metabolizing enzymes (CYP3A4, CYP2D6,
CYP1A2), inducers or inhibitors of these enzymes may change the clearance and, hence the half-life of
ondansetron. In patients treated with potent inducers of CYP3A4 (i.e., phenytoin, carbamazepine, and rifampin),
the clearance of ondansetron was significantly increased, and ondansetron blood concentration was decreased.
Serotonergic
Serotonin syndrome (including altered mental status, autonomic instability, and neuromuscular symptoms) has
been described following concomitant use of 5-HT3 receptor antagonist and serotonergic drugs, including
selective serotonin reuptake inhibitors (SSRIs) and serotonin and noradrenaline reuptake inhibitors (SNRIs).

8. Apomorphine
Based on reports of profound hypotension and loss of consciousness when apomorphine was administered
with ondansetron, concomitant use of apomorphine with ondansetron is contraindicated.
Tramadol
When used together, Zofran may increase patient-controlled administration of tramadol. Monitor patient to
ensure adequate pain control when ondansetron is administered with tramadol.
Chemotherapy
Carmustine, etoposide, and cisplatin do not affect the phamacokinetics of ondansetron. In a crossover trial
in 76 pediatric patients, intravenous ondansetron did not increase systemic concentrations of high-dose
methotrexate.

9. Alfentanil and Atracurium
Ondansetron does not alter the respiratory depressant effects produced by alfentanil or the
degree of neuromuscular blockade produced by atracurium (Cerenex Pharmaceutical, n.d.,
Strativa Pharmaceutical, n.d.).

10. Cardiovascular
Rarely and predominantly with intravenous ondansetron, transient ECG changes including QT interval
prolongation have been reported.
Adverse Drug Reaction
General
Flushing. Rare cases of hypersensitivity reactions, sometimes severe (e.g., anaphylactic reactions,
angioedema, bronchospasm, shortness of breath, hypotension, laryngeal edema, stridor) have also been
reported. Laryngospasm, shock, and cardiopulmonary arrest have occurred during allergic reactions in
patients receiving injectable ondansetron.
Hepatobiliary
Liver enzyme abnormalities.

11. Lower Respiratory
Hiccups
Neurology
Oculogyric crisis, appearing alone, as well as with other dystonic reactions.
Skin
Urticaria, Stevens-Johnson syndrome, and toxic epidermal necrolysis.
Eye Disorders
Cases of transient blindness predominantly during intravenous administration, have been
reported. These cases of transient blindness were reported to resolve within a few minutes up to
48 hours (Cerenex Pharmaceutical, n.d., Strativa Pharmaceutical, n.d.)

12. Side Effects
General
The most frequently reported side effects are a headache, constipation, and diarrhea.
Nervous system
Dizziness occurred during rapid IV administration.
Headache occurred more often in the oral dissolving tablet formulation when taken with water.
Other
Wound problem occurred at the surgical site in patients given this drug for the treatment of
postoperative nausea and vomiting.

13. Ocular
Transient visual disturbances, blurred vision, and temporary blindness occurred
predominantly during rapid IV administration. Many of the cases of blindness resolved within a
few minutes to approximately 28 hours. Most patients were receiving concomitant chemotherapy
with cisplatin.
Respiratory
Laryngospasm occurred during allergic reactions in patients given the IV formulation
Psychiatric
Anxiety/agitation, disturbance in behavior /conduct, sleep disturbance (Cerenex
Pharmaceutical, n.d., Strativa Pharmaceutical, n.d.).

14. Ondansetron clinical pharmacokinetics
Ondansetron is a potent and highly selective serotonin 5-HT3-receptor antagonist which is
completely and rapidly absorbed from the gastrointestinal tract after oral administration and does
not accumulate with repeated oral administration. Owing to hepatic first-pass metabolism, its
bioavailability is only about 60% compared with ondansetron administered by infusion over 15
minutes.
Ondansetron is widely distributed (volume of distribution approximately 160L) and binds
moderately (70 to 76%) to plasma protein. The elimination half-life averages about 3.8 +/- 1
hours. Clearance occurs by hepatic metabolism (95%) rather than renal excretion.

15. Drug Binding Issue
Fentanyl
Concomitant use of 5-HT3 receptor antagonist with agents that possess or enhance
serotonergic activity such as selective serotonin reuptake inhibitors (SSRIs), selective serotonin-
norepinephrine reuptake inhibitors (SNRIs), monoamine oxidase inhibitors (MAOIs), tricyclic
antidepressants (TCAs), 5-HT1 receptors agonist (triptans), ergot alkaloids, St. John’s Wort,
tramadol may potentiate the risk of serotonin syndrome, which is a rare but severe and potentially
fatal condition thought to result from hyperstimulation of brainstem 5-HT1A and 2A receptors.

16. Interdisciplinary teamwork is an important model for delivering effective and safe health care to the
patients. Nurses and pharmacist are essential members of one team. Through team efforts, nurses and
pharmacist can enhance medication safety. Through collaboration, the team can face and resolve issues with
unity and patient advocacy.
Antiemetic agents are among the most frequently prescribed medication in the emergency department (ED),
both pediatrics, adults and geriatrics. Based on the safety and efficacy of ondansetron, it may be used as a
first-line agent for relief of nausea and vomiting in the ED (Patanwala, Amini, Hays, & Rosen, 2010).
It is the premise of this drug study and application to equipped nurses with pharmacological and
pharmacotherapeutic information and knowledge necessary for the delivery of a safe patient care in
emergency setting.
Findings/Conclusion:

17. References
ASHP: American Society of Health-System Pharmacist Council on Pharmacy Practice. (2008). ASHP
statement on pharmacy services to the emergency department. American Journal Health-System
Pharmacy, 65, 2380-2383.
Becker, D. E. (2010). Nausea, vomiting, and hiccups: A review of mechanism and treatment. Anesthesia
Progress, 57(4), 150-157. doi: 10.2344/0003-3006-57.4.15
Cerenex Pharmaceuticals. (n.d.). Product information zofran ondansetron. NC: Research Triangle Pk.
Cheng, A. (2011). Emergency department use of oral ondansetron for acute gastroenteritis related
vomiting in infants and children. Paediatric Child Health, 16(3), 177-179. Retrieved from
https://www.cps.ca/documents/position/oral-ondansetron
Elliott, E. J. (2011). Acute gastroenteritis in children. British Medical Journal, 334, 35-40.
Patanwala, A.E., Amini, R., Hays, D.P., & Rosen, P. (2010). Antiemetic therapy for vomiting in the
emergency department. Journal of Emergency Medicine, 39(3),330-336.
doi:10.1016/j.jemermed.2009.08.060
Strativa Pharmaceuticals, a Division of Par Pharmaceuticals, Inc. (n.d.). Product information zuplenz
ondansetron. Woodcliff Lake, NJ.
Zofran-Novartis. (1991). Highlights of prescribing information. Retrieved from
http://www.pharma.us.novartis.com//product/pi/pdf/zofran.pdf