Ondansetron: a review of its use as an antiemetic in children

Amino acids in transmembrane domain two influence anesthetic enhancement of serotonin-3A receptor function

Alcohols and volatile anesthetics affect the function of members of the nicotinic acetylcholine (nACh) superfamily of receptors. Studies on glycine and GABA(A) receptors implicate amino acid residues within transmembrane (TM) regions two and three of these receptors as critical for alcohol and anesthetic enhancement of receptor function. The serotonin-3 (5-HT(3)) receptor is a member of the nicotinic acetylcholine receptor superfamily, sharing sequence and structural homology with the other members. We tested the hypothesis that amino acids of the 5-HT(3) receptor homologous to those shown to affect alcohol and anesthetic potentiation in GABA(A) and glycine receptors also determine the effects of these compounds on the 5-HT(3) receptor. Six 5-HT(3A) mutant cDNAs were generated by site-directed mutagenesis of two amino acids, phenylalanine-269 (14') and lecucine-270 (15') in transmembrane domain two (TM2). When assayed electrophysiologically in Xenopus oocytes, wild-type 5-HT(3) receptors exhibit enhancement of function by enflurane, halothane, isoflurane, chloroform and ethanol, but not by decanol and propofol. Mutations in transmembrane domain two markedly affected alcohol and anesthetic enhancement of 5-HT(3) receptor function. Some mutations had differential effects on the abilities of the isomers enflurane and isoflurane to potentiate 5-HT(3) receptor function.

Options for the prevention and management of acute chemotherapy-induced nausea and vomiting in children

The current standard of care with respect to preventing acute chemotherapy-induced nausea and vomiting (CINV) in children includes the administration of a 5-HT(3) antagonist with or without a corticosteroid, depending on the emetogenicity of the chemotherapy to be given. Problems in assessing the emetogenicity of chemotherapy regimens and nausea severity in children may influence the degree of success of CINV prophylaxis. Nevertheless, the majority of children who receive chemotherapy today experience moderate to complete control of acute CINV when given appropriate antiemetic prophylaxis. If children vomit or experience nausea despite appropriate prophylaxis, then measures must be taken to treat these symptoms since these children are likely to go on to experience delayed or anticipatory CINV. However, appropriate selection of interventions to treat acute CINV in children is limited by the lack of rigorous evidence to support one approach over another. Lorazepam is suggested as an immediate agent for the treatment of acute CINV. Doses and frequencies of the 5-HT(3) antagonist and corticosteroid administered for initial prophylaxis should also be maximized. Further treatment must be tailored to the circumstances and preferences of each child and family. Options include crossover to another 5-HT(3) antagonist, or administration of an adjunctive antiemetic such as metopimazine, low dose metoclopramide, domperidone, alizapride, nabilone, scopolamine, prochlorperazine, or chlorpromazine. Complementary interventions such as acupuncture, hypnosis, counseling, or ginger may also be of benefit. Further study is required to establish optimal antiemetic strategies in children.

Management of postoperative nausea and vomiting in children

In spite of improvements in anesthesia techniques, the 'big little problem' of postoperative nausea and vomiting (PONV) still exists. PONV can prolong recovery room stay and hospitalization, and is one of the most common causes of hospital readmission after day surgery. While there is little evidence to support prophylactic administration of antiemetics in patients at low risk of PONV, the higher risk population could benefit from the use of adequate antiemetic drugs. A wide variety of pharmacological approaches have been reported to be effective, as well as some nonpharmacological approaches. Antiemetic drugs available to treat or prevent PONV include phenothiazines, antihistamines, anticholinergics, benzamides, butyrophenones and 5-HT(3) antagonists. Since available drugs still present undesired adverse effects and are not completely able to control PONV, clinical investigations are ongoing for more effective and better tolerated agents; indeed, the ideal antiemetic drug might be cost-effective for routine use.

Ondansetron for the prevention and treatment of nausea and vomiting following pediatric strabismus surgery

BACKGROUND

Neither droperidol nor ondansetron has been proven completely effective, and there are conflicting data comparing the efficacy of the two agents. The purpose of this study was to compare the efficacy, safety and cost of a combination of ondansetron administered intravenously in the operating room followed by oral ondansetron treatment at home with the more commonly used treatment of intravenous droperidol therapy and oral dimenhydrinate therapy, for the prevention and treatment of postoperative nausea and vomiting in children undergoing strabismus surgery.

METHODS

Double-blind randomized clinical trial with parallel comparison groups. All patients aged 6 months to 18 years who underwent strabismus surgery at a pediatric hospital in Montreal between Nov. 13, 2000, and June 12, 2001, were included. The exclusion criteria were nausea or vomiting, or use of antiemetics or narcotics in the 24 hours preceding surgery, and past history of hepatic, gastric or renal disease. The outcome measures were frequency of nausea and vomiting, severity of nausea and adverse effects in hospital, during transportation home and during the first 24 hours at home. Data were obtained through nursing notes and through a telephone interview conducted 24 to 48 hours after discharge.

RESULTS

Of the 208 eligible patients, 172 were randomly assigned to the study groups (88 to the ondansetron group and 84 to the droperidol/dimenhydrinate group). We found no statistically significant difference in the incidence of nausea and vomiting in hospital or at home between the two groups (25.3% vs. 31.6%, p = 0.371). There was a significant difference between the two groups in the rate of vomiting during transportation home (3.6% vs. 12.6%, p = 0.044). The incidence of severe nausea was 14.4% with ondansetron and 15.4% with droperidol, a nonsignificant difference (p = 1.00). No significant difference was observed between the two groups in the incidence of any nausea (p = 0.434) or adverse effects (p = 0.220). We calculated that the combination of droperidol and dimenhydrinate was seven times less costly than the ondansetron regimen.

INTERPRETATION

In this study, the efficacy and safety of intravenous administration of droperidol followed by oral use of dimenhydrinate did not differ from that of intravenous followed by oral use of ondansetron in children undergoing strabismus surgery. Since treatment with ondansetron is much more costly than the combination of droperidol and dimenhydrinate, at this time the use of ondansetron in the prevention and treatment of vomiting and nausea in this population may not be beneficial on a cost basis if all other variables are considered.

Pharmacotherapy of gastro-oesophageal reflux disease in children: focus on safety

Gastro-oesophageal reflux (GOR) disease is very common and, in the majority of infants, is physiological. However, untreated GOR disease in infants and children is associated with a decrease in quality of life for the child and their parents. It may also cause sometimes more severe complications, such as oesophagitis, and causing, in rare cases, failure to thrive, oesophageal stricture, apnoea and even death. Every therapeutic intervention (non-drug treatment, medical treatment and surgery) is associated with morbidity and even mortality. Moreover, efficacy data of many medications in children are non-existing, limited or disappointing. The safety profile of cisapride is comparable to that of other therapeutic interventions or to the risk of non-treatment. Therefore, the therapeutic approach of GOR disease in infants and children needs to be well-balanced, considering therapeutic efficacy and side effects. This review will focus on the side effects of the different therapeutic options.