Antiemetic of Choice for an Aeromedical Pediatric Retrieval Team - Essay Example

? Antiemetic of choice for an aeromedical paediatric retrieval team of the Health sciences and medicine of the July 23, 2012 You are the Medical Director for an aeromedical paediatric retrieval team staffed by critical care paramedics. Which, if any, anti-emetic would you choose, and why? Include basic pharmacology of the drug, dosages, indications, contraindications, advantages, disadvantages and potential side effects. Antiemetic of choice for an aeromedical paediatric retrieval team Introduction Paediatric patients undergoing aeromedical transfer are prone to motion sickness resulting in a higher incidence of nausea and vomiting as compared to adults. In addition, the underlying disease process itself, such as gastroenteritis, chemotherapy or a perioperative state of the patient may mandate use of antiemetics (Antonarakis & Hain, 2004; Bolton, Myles, Carlin & Nolan, 2007; Levine, 2009). Various groups of antiemetics such as antihistamines (promethazine, dimenhydrinate), 5-HT3 receptor antagonists (Ondansetron), dopamine antagonists (metoclopramide, domperidone), anticholinergics (hyoscine, scopolamine) etc have been studied in the adult population and have well documented and evidence based indications and adverse effects (Enarson, Gouin & Goldman, 2011). However, as most of these medications have side effects in children, they are either not recommended in children or are not licensed for paediatric use (Harris C, Wilkinson F, Mazza D, Turner T, 2008). Despite this, antiemetics are routinely prescribed for paediatric nausea and vomiting (Manteuffel, 2009). In motion sickness, labyrinthine mediated pathways are very effectively abolished by antihistamines and anticholinergics. Therefore, these are very effective as prophylaxis against motion sickness in adults. Nevertheless, adverse effects of these drugs are not acceptable in paediatric patient population and thus 5 HT3 antagonists, despite being less effective, are far safer to use in this age group. Ondansetron, the representative and first drug of 5 HT3 receptor antagonist group has been used in paediatric patients for quite some time now and no serious adverse effects have been noted (Apfel, 2010; Cohen, 2007). It is one of the most common drugs used for paediatric emergency department nausea and vomiting (Mee, Egerton-Warburton & Meek, 2011). Moreover, its efficacy in chemotherapy and radiation induced vomiting and postoperative nausea and vomiting is well proven. This article will discuss ondansetron as the drug of choice in motion induced and other causes of nausea and vomiting in an aeromedical paediatric retrieval team. Pathophysiology of emesis The basic mechanism for induction of emesis is stimulation of vomiting centre present in the medulla which is done by various neurotransmitters such as serotonin, dopamine, histamine, acetylcholine and neurokinin (NK1). These neurotransmitters act at various receptors located at chemoreceptor trigger zone (CTZ), gastrointestinal tract, vestibular apparatus and cerebrum, which transmit information to vomiting centre via vagus nerve. CTZ itself can be stimulated chemically or through vagus nerve. Thus, central or peripheral stimulation via complex neural and humoral mechanism, leads to nausea and vomiting (Cohen, 2007). Motion sickness particularly results from afferents from vestibular apparatus and is a risk factor predictive of postoperative and chemotherapy induced vomiting (Antonarakis & Hain, 2004). Therefore, Ondansetron, which is effective for post operative and chemotherapy induced vomiting, must be effective as corollary in the management of motion sickness, although Golding & Gresty (2005) mentioned in their review on motion sickness that Ondansetron is not effective in motion sickness. Ondansetron: Basic pharmacology Ondansetron is a selective antagonist at the serotoninergic 5HT3 receptors present at the vagus nerve and CTZ. Oral bioavailability is good and half life in plasma is 4 hours. The drug is well absorbed and extensively metabolised in the body. Its dose should be reduced in hepatic failure patients. Ondansetron is metabolised by CYP2D6 enzyme system. Genetic polymorphism may result in a faster metabolism so that the drug may be rendered less effective (Apfel, 2010). Ondansetron: Dosage Oral tablets as well as parenteral solutions for intramuscular and intravenous injection are available. Paediatric dose is 0.1 to 0.15 mg/kg and adult dose is usually 4 mg, up to a maximum of 8 mg (Levine, 2009). Ondansetron: Indications Ondansetron hydrochloride is an antiemetic which is indicated in the prevention and management of nausea and vomiting caused by highly and moderately emetogenic chemotherapy, surgery and exposure to anaesthetic agents, acute gastroenteritis and motion sickness. Ondansetron: Contraindications Ondansetron is contraindicated in persons with a known hypersensitivity to the drug. Also, United States food and drug administration has issued a contraindication for the use of Ondansetron with apomorphine. This combination has resulted in severe hypotension and loss of consciousness (FDA, 2010). Ondansetron: Advantages & Disadvantages Lack of any major side effect has proven advantageous. Moreover, it is useful in preventing dehydration and further fluid loss in patients with gastroenteritis (Levine; 2009; Levine, 2011; Simpson & Teach, 2011). As an antiemetic agent, it finds its use in preventing airway contamination in children with depressed consciousness. It was found superior to metoclopramide in reducing vomiting in postoperative children (Bolton et al, 2007). There is minimal chance of drug interactions and no sedation and no extrapyramidal or dystonic reactions (Levine; 2009). Very rare significant electrocardiographic abnormalities occur and therapeutic index is favourable (Cohen, 2007). However, caution is still to be exercised in vulnerable population where QT prolongation can occur. Also, the drug is available at a much lesser cost so that it can be widely used. In children at a high risk of nausea and vomiting, combination therapy has been found to be more effective. Ondansetron in combination with dexamethasone is superior to single drug prophylaxis in high risk patients (Cohen, 2007). Ondansetron: Potential side effects Side effects with Ondansetron are minor and include headache, flushing and diarrhoea or constipation, urticaria and fever (Antonarakis & Hain, 2004; Levine 2009; Fedorowicz, Jagannath & Carter, 2011). Rare but serious adverse effects include ECG changes involving sodium channels and raised liver enzymes. Incidence of acute dystonic reactions is very less as compared to dopamine antagonists. Conclusion Aeromedical transport is associated with nausea and vomiting in paediatric patients. As ondansetron, a 5HT3 antagonist, has been found effective in children in various settings including motion sickness, it is the drug of choice for an aeromedical paediatric retrieval team. It plays a role in almost all types of nausea and vomiting, has a low incidence of side effects and thus, has an advantage over other drugs used for the same purpose such as Metoclopramide or antihistamines. As more evidence regarding its efficacy and safety in this particular age group comes into light, it is likely to be formally recommended for this use. References Antonarakis, E. S., & Hain, R. D. W. (2004). Nausea and vomiting associated with cancer chemotherapy: drug management in theory and in practice. Archives of Diseases of Childhood, 89, 877–880. doi: 10.1136/adc.2003.037341. Apfel, C. C. (2010). Postoperative nausea and vomiting. In R. D. Miller, L. I. Eriksson, L. A. Fleisher, J. P. Wiener-Kronish & W. L. Young (Eds.), Miller’s Anesthesia (pp. 2729 -2755). Philadelphia: Churchill Livingstone Elsevier. Bolton, C. M., Myles, P. S., Carlin, J. B., & Nolan, T. (2007). Randomized, double-blind study comparing the efficacy of moderate-dose metoclopramide and ondansetron for the prophylactic control of postoperative vomiting in children after tonsillectomy. British Journal of Anaesthesia, 99(5), 699–703. doi:10.1093/bja/aem236. Cohen, I. T. (2007). An overview of the clinical use of ondansetron in preschool age children. Therapeutics and Clinical Risk Management, 3(2), 333–339. Enarson, P., Gouin, S., & Goldman, R. D. (2011). Dimenhydrinate use for children with vomiting. Canadian Family Physician, 57, 431-432. Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3076472/pdf/0570431.pdf Fedorowicz, Z., Jagannath, V. A., & Carter, B. (2011). Antiemetics for reducing vomiting related to acute gastroenteritis in children and adolescents. Cochrane Database of Systematic Reviews, 9, CD005506. doi: 10.1002/14651858.CD005506.pub5. Golding, J. F., & Gresty, M. A. (2005). Motion sickness. Current Opinion in Neurology, 18, 29–34. Retrieved from http://graphics.tx.ovid.com/ovftpdfs/FPDDNCFBGEPLPB00/fs047/ovft/live/gv024/ 0019052/00019052-200502000-00007.pdf Harris, C., Wilkinson, F., Mazza, D., Turner, T. (2008). Evidence based guideline for the management of diarrhoea with or without vomiting in children. The Royal Australian College of General Practitioners, 37(6), 22-29. Retrieved from http://www.racgp.org.au/Content/NavigationMenu/Publications/AustralianFamilyPh s/20 8issues/afp200806paediatricconditions/200806supplementdiarrhoea.pdf Levine, D. A. (2009). Antiemetics for acute gastroenteritis in children. Current Opinion in Pediatrics, 21, 294–298. doi:10.1097/MOP.0b013e32832b104b. Levine, D. A. (2011). Oral ondansetron decreases vomiting, as well as the need for intravenous fluids and hospital admission, in children with acute gastroenteritis. Evidence-Based Medicine (2011). doi:10.1136/ebmed.2011.100355 Manteuffel, J. (2009). Use of antiemetics in children with acute gastroenteritis: Are they safe and effective? Journal of Emergencies, Trauma and Shock, 2(1), 3-5. Retrieved from http://www.onlinejets.org/article.asp?issn=0974- 2700;year=2009;volume=2;issue=1;spage=3;epage=5;aulast=Manteuffel Mee, M. J., Egerton-Warburton, D., & Meek, R. (2011). Treatment and assessment of emergency department nausea and vomiting in Australasia: a survey of anti-emetic management. Emergency Medicine Australasia, 23(2), 162-168. doi: 10.1111/j.1742 6723.2011.01386.x. Simpson, J. N., & Teach, S. J. (2011). Pediatric rapid fluid resuscitation. Current Opinion in Pediatrics, 23, 286–292. doi:10.1097/MOP.0b013e3283460599. U. S. Food and Drug Administration (FDA) (2010). Safety label changes. Retrieved from http://www.fda.gov/Safety/MedWatch/SafetyInformation/ucm230231.htm Read More

 

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