1872 Gastrointestinal Omdom; Omecer-D; Omecid-D; Omecid-RD; Omecip-D; Orne­ Administration. Ondansetron has been successfully used cos-O; Omeezol-D; Omejel-DM; Omelax-D; Omen-D; Ome­ Uses and Administration by continuous subcutaneous infusion to control intractable praz-HP Kit; Omeraze-D; Omeris-D; Omesun-D; Omesym-D; Ondansetron is a 5-HT3 antagonist (5-HT3 -receptor nausea and vomiting.1 Despite concern about the low pH Omevar-D; Omez Insta; Omez-D; Omfact-D; Omibase-D; Ornic­ antagonist) with antiemetic activity. It is used in the of ondansetron injection there was no problem with the O; Omicas-D; Omicool-D; Omidec; Omidip; Omidom; Omiflux; management of nausea and vomiting induced by skin at the infusion site. An oral protocol for chemother­ Omig-DM; Omilee-D; Omitive-D; Omitop-DM; Omitop; Omi­ cytotoxic chemotherapy and radiotherapy. It is also used apy-induced emesis in children has been described;2 effi­ zol-D; Omkair-D; Omlink-D; Omlo-D; Ommac Plus; Omore-D; for the prevention and treatment of postoperative nausea cacy was similar to intravenous use. Omoxitin; Ompli-D; Ompraz-D; Omprest-D; Ornracap-DM; and vomiting. For the management of nausea and vomiting, Omriz-D; Omven-D; Omzee-D; Onazole-DP; Onazole-RD; 1. Mulvenna PM, Regnard CFB. Subcutaneous ondansetron. Lancet 1992; and the important role of 5-HT antagonists, see p. 1811.3. 339: 1059. Oned; Onto-D; Op-Zole D; Opaz-DM; Opel-D; Opera-D; Oraz­ 3 Ondansetron is given by intramuscular or slow 2. Walker PC, et al. Promoting the use of oral ondansetron in children D; Orole-D; Ospicid-D; Ossum-D; OTC HP Kit; OTG-D; Otto-D; 58: intravenous injection or infusion as the hydrochloride, receiving cancer chemotherapy. Am J Health-Syst Pharm 2001; 598- Ozed-D; Ozodom; Ozol-D; Pacidom-0; Malaysia: Pylobact 602. Combi; Mex. : Pridamiral Pack; NZ: Losee Hp7; Philipp.: OAC orally as the hydrochloride or base, or rectally as the base. Hp7t; Rus.: Domstal-0 (,[\oMCTIUI-0); Omez D (0Me3 ,[(); Pylo­ Doses are expressed in terms of the base. Ondansetron bact (IImm6rucr); Ukr.: Limzer (JiiM3ep); Omez-D (0Me3-,[(); hydrochloride 4. 99 mg is equivalent to about 4 mg of Administration in children. Ondansetron is used in chil­ Pylobact Neo (I1rum6aKTHeo ); USA: Omeclamox-Pak; Zegerid. ondansetron base. dren for the management of nausea and vomiting induced Numerous dosing schedules of ondansetron have been by cytotoxic chemotherapy and radiotherapy. It is also used for the prevention and treatment of postoperative Arg.: Dioxaflex Protect; Philipp.: Skelan used; some typical examples are cited below. Used as an adjunct in:. nausea and vomiting. Ondansetron is given by slow intra­ Protect; UK: Axorid. For highly emetogenic chemotherapy the following dose schedules appear to be equally effective in preventing acute venous injection or infusion as the hydrochloride, or oral­ emesis: ly as the hydrochloride or base. Doses are expressed in PharmacopoeialPreparations a single dose of 8 mg by slow intravenous or terms of the base. BP 2014: Gastro-resistant Omeprazole Capsules; Gastro-resistant • In the USA a licensed regimen for chemotherapy­ Omeprazole Tablets; Omeprazole Oral Suspension; intramuscular injection immediately before treatment induced nausea and vomiting in children over 6 months of USP 36: Omeprazole Delayed-Release Capsules; Omeprazole or Oral Suspension. age is ondansetron 150 micrograms/kg by intravenous 8 mg by slow intravenous or intramuscular injection infusion 30 minutes before moderately to highly • immediately before treatment, either followed by a emetogenic chemotherapy, repeated 4 and 8 hours after continuous intravenous infusion of l mg/hour for up to the first dose. Alternatively, for children aged 4 to 11 years, 24 hours, or by a further two doses of 8 mg two to four an oral dose of 4mg may be given 30 minutes before the hours apart start of moderately emetogenic chemotherapy, with subsequent 4-mg doses given 4 and 8 hours thereafter. An or oral dose of 4mg three times daily may be given for 1 to 2 a single dose of 16 mg given by intravenous infusion over days after the end of chemotherapy. • at least 15 minutes immediately before treatment, which In the UK, ondansetron is licensed for use in children can be followed by a further 2 doses of 8 mg by slow aged from 6 months and doses are calculated using body­ intravenous or intramuscular injection four hours apart weight or body-surface; weight-based dosing results in higher daily doses compared with those based on body­ or surface. In a typical regimen based on body-surface, an 150 micrograms/kg (maximum 16 mg) by intravenous intravenous dose of ondansetron 5 mg/m2 (maximum 8 mg) • infusion over 15 minutes, beginning 30 minutes before is infused (over at least 15 minutes) immediately before chemotherapy, followed by a further 2 doses four hours chemotherapy and followed after 12 hours by oral dosing USP 36: (Ondansetron). A white to off-white powder. apart for up to 5 days: children aged from 6 months and less than 0.6 m2 body- Sparingly soluble in water; very soluble in acid solutions. or • Store in airtight containers. Protect from light. surface: 2 mg every 12 hours a 16-mg suppository rectally, given 1 to 2 hours before from 6 months and 0.6 m2 and over: 4mg every 12 hours • • treatment When using body-weight, an intravenous dose of ondan­ Ondansetron Hydrochloride or setron 150 micrograms/kg (maximum 8 mg) is given immediately before chemotherapy and repeated every 4 (BANM. USAN, r!NNM) a single oral dose of 24 mg taken 30 minutes before the • hours for up to 3 doses. This is followed after 12 hours by start of single-day chemotherapy oral dosing for up to 5 days: The efficacy of ondansetron in highly emetogenic chemo­ body-weight lO kg and less: 2 mg every l2 hours • therapy may be enhanced by giving intravenous dexa­ over lO kg: 4 mg every 12 hours • methasone sodium phosphate 20 mg before chemotherapy. The daily dose of ondansetron by any route should not Similar regimens to those given above are used for exceed 32 mg. preventing acute emesis with less emetogenic chemotherapy While ondansetron is not licensed in the UK for and/or radiotherapy and also include: radiotherapy-induced nausea and vomiting in children, 8 mg given orally or by slow intravenous injection up to 2 • the BNFC recommends the same doses as those used for hours before treatment, followed by an oral dose of 8 mg chemotherapy-induced nausea and vomiting (above). given 8 to l2 bours later A protocol for oral ondansetron dosage, with similar To protect against delayed emesis these regimens are efficacy to intravenous use, has also been described, see followed by oral ondansetron 8mg twice daily, or 16mg Administration, above. rectally once daily, for up to 5 days after the end of a course For the prevention and treatment of postoperative of chemotherapy. Pharmacopoeias. In Chin., Bur. (see p. vii), and US. nausea and vomiting in children aged from 1 month, To prevent postoperative nausea and vomiting the 100micrograms/kg may be given by slow intravenous Ph. Eur. 8: (Ondansetron Hydrochloride Dihydrate). following doses may be given: injection, up to a maximum dose of 4mg. white or almost white powder. Sparingly soluble in water 16 mg orally an hour before anaesthesia and in alcohol; slightly soluble in dichloromethane; soluble • in methyl alcohol. Protect from light. or Administration in the elderly. Most licensed product infor­ mation for ondansetron states that dose adjustments for USP 36: (Ondansetron Hydrochloride). A white to off-white 8 mg orally an hour before anaesthesia followed by 2 • patients over 65 years of age are not necessary. However, powder. Sparingly soluble in water and in alcohol; very further doses of 8 mg at 8-hour intervals slightly soluble in acetone, in chloroform, and in ethyl the product information for one preparation (Zofran; GSK, acetate; slightly soluble in dichloromethane and in or UK) recommends that patients over 7 5 years of age are given an initial dose of 8 mg by intravenous infusion over isopropyl alcohol; soluble in methyl alcohol. Store in a single dose of 4 mg by slow intravenous or • 15 minutes for the management of nausea and vomiting airtight containers at a temperature of 25 degrees, intramuscular injection at induction of anaesthesia induced by cytotoxic chemotherapy and radiotherapy; this excursions permitted between 15 degrees and 30 degrees. For the treatment of postoperative nausea and vomiting a may be followed by a further 2 infusions of 8 mg given at Protect from light. single dose of 4 mg by intramuscular or slow intravenous least four hours apart. injection is recommended. For dosing in children, elderly patients, or those with Incompatibility. Ondansetron hydrochloride and dexa­ hepatic impairment, see below. Administration in hepatic impairment. Licensed product methasone sodium phosphate were not compatible when information recommends that the dose of ondansetron high concentrations were combined in polypropylene syr­ Reviews. should not exceed 8 mg daily in patients with moderate or inges.1 Lower concentrations (up to 640 micrograms/mL of 1. Perez EA. A risk-benefit assessment of serotonin 5-HT3 recepto� severe hepatic impairment. When this dose was given ondansetron and 400 micrograms/mL of dexamethasone antagonists in antineoplastic therapy-induced emesis. Drng Safety 1998; intravenously to patients with hepatic impairment, those phosphate) were stable in 50 mL containers of infusion 18: 43-56. with severe impairment showed an increase in the area fluid for 30 days under refrigeration. Compatibility has 2. Gregory RE, Ettinger DS. 5-HT3 receptor antagonists for the prevention of chemotherapy-induced nausea and vomiting: a comparison of their under the plasma concentration/time curve and in the been reported for 24 hours in plastic syringes at 4 degrees pharmacology and clinical efficacy.