Maximum daily dose of Ondansetron

From Micromedex

Important Note
The single 32-mg IV dose is no longer an approved dose because of the risk of QT-interval prolongation and torsades de pointes. Maximum single IV dose is 16 mg

General Dosage Information
Ondansetron hydrochloride tablets and oral solution are bioequivalent and interchangeable

Chemotherapy-induced nausea and vomiting, Initial and repeat courses of highly emetogenic chemotherapy; Prophylaxis
0.15 mg/kg IV starting 30 minutes prior to chemotherapy, repeat 4 and 8 hours after the first dose; MAX single IV dose 16 mg
24 mg orally 30 minutes prior to chemotherapy

Chemotherapy-induced nausea and vomiting, Initial and repeat courses of moderately emetogenic chemotherapy; Prophylaxis
0.15 mg/kg IV infusion over 15 minutes starting 30 minutes prior to chemotherapy, repeat 4 and 8 hours after the first dose; MAX single IV dose 16 mg
8 mg orally 30 minutes prior to chemotherapy and repeat in 8 hours, then 8 mg every 12 hours for 1 to 2 days postchemotherapy

Drug-induced nausea and vomiting
8 mg OR 16 mg IV once daily (off-label dosage)

Hyperemesis gravidarum
10 mg IV administered over 30 minutes every 8 hours (off-label dosage)
8 mg IV twice daily (off-label dosage)

Injection site pain
4 mg IV pretreatment (off-label dosage)

Irritable bowel syndrome with diarrhea
Initial, 4 mg orally once daily; may titrate up to 8 mg orally 3 times per day as needed (off-label dosage)

Multiple sclerosis – Nausea
8 mg orally twice daily (off-label dosing)

Panic disorder
1 to 2 mg IV twice daily (off-label dosage)

Postoperative nausea and vomiting; Prophylaxis
4 mg IV/IM undiluted immediately prior to anesthesia induction or postoperatively; a second dose does not provide additional benefit
16 mg orally 1 hour before anesthesia induction

Pruritus
(Cholestatic itching) 8 mg orally once daily for first day and twice daily for 6 additional days (off-label dosage)
(Palmoplantar pruritus) 8 mg orally once daily. May reduce to once weekly (off-label dosage; Downs et al 1998).
(Morphine-induced) 4 mg IV or orally given once (off-label dosage)

Radiation-induced nausea and vomiting; Prophylaxis
Single high-dose fraction or daily fractionated radiotherapy to abdomen: 8 mg orally 1 to 2 hours prior to radiotherapy and every 8 hours after first dose for 1 to 2 days.
Total body irradiation radiotherapy: 8 mg orally 1 to 2 hours prior to each fraction of radiotherapy.

Schizophrenia, Refractory; Adjunct
4 to 8 mg orally once daily as an adjunct treatment (off-label dosage)

Shivering, Postanesthesia; Prophylaxis
4 mg or 8 mg IV once, usually before induction of anesthesia (off-label dosage)

As per the reference(Lexicomp Online), yes you can up to 48 mg per day divided into 3 doses, but I think for pedia patient you will not reach this dose unless obese patient more than 100 Kg.

Note: Single IV doses >16 mg are no longer recommended by the manufacturer due to the potential for QT prolongation

To avoid this risk, you may consider addition of another group of treatment such Substance P/Neurokinin 1 Receptor Antagonists per MASCC guidelines, antiemetic regimen also includes Dexamethasone and aprepitant or fosaprepitant.

The maximum daily dose of Ondansetron varies according to the condition you’re giving it for, but usually it’s 16-32 mg daily. Some factors can impact your decision, like age, indication, baseline QTc interval, and risk of emesis for chemotherapeutic agents.

Achieving your goal using 2-3 agents with different mode of action would be a good option when you evaluate the risks vs benefits of giving ondansetron at doses > 32 mg/day.

If your recommending Ondansetron as a prophylaxis against CINV, and the emetogenic chemotherapy is high, then it’s recommended to give the patient a loading dose of Ondansetron prior starting chemo (16mg), and two doses subsequently (8 mg each dose).

The previous recommendation I wrote was adopted from NCCN antiemetic guidelines. According to Ondansetron new label, hence, guideline recommendations had changed, the recommendations are as follows:

For CINV prevention, IV route:

0.15 mg/kg over 15 min administered 30 min before chemotherapy, then 4 and 8 hr after first dose; not to exceed 16 mg (32 mg no longer recommended because of increased risk of QT prolongation)

Kindly note that the risk of QT prolongation is additive, and if your patient has a low baseline QT interval, does not receive other medications that might prolong QT internal, negative CVD history, and no other antiemetics are available or contraindicated, then you might follow the 32 mg/day as long as you can monitor your patient.

You can find these recommendations on 2012 version from NCCN, antiemetic guidelines:

http://www.jnccn.org/content/10/4/456.full.pdf+html

or

https://mega.nz/file/WwZixZpb#7XglIAJF3LLfjKDwDgswjMtHZHYphya0-L6olWT9UzU

Kindly note label changed at:
http://reference.medscape.com/drug/zofran-zuplenz-ondansetron-342052

Hope that answers your question.

In lexi the dose is writen as follows

IV: 0.15mg/kg/dose (maximum : 16 mg/dose) administered over 15 minutes for 3 doses, beginning 30 minutes prior to chemotherapy, followed by subsequent doses4 and 8 hours after the first dose.

So, the maximum total dose is 48 mg divided in three doses , to cover before and during chemotherapy perfusion.

It would be prudent to review the doses based on international recommendations. Ondansetron 16mg is not longer recommended as a single dose nor is the 32mg dose daily dose. As mentioned QTc prolongation is quite with these class of medications.