THERAPEUTICS

Brands

• Zofran, Zuplenz

Generic?

• Yes

Class

• Antiemetic

Commonly Prescribed for

(FDA approved in bold)

• Prevention of nausea and vomiting (chemotherapy, radiotherapy, postoperative)

• Nausea and vomiting (pregnancy)

• Pruritus (opioid related)

• Acute gastroenteritis vomiting (children)

How the Drug Works

• Selective blocking agent of 5-HT3 receptors on both peripheral vagal nerve terminal and central chemoreceptor trigger zone (area postrema)

How Long Until It Works

• Usually works in less than 30 minutes

If It Works

• Use at lowest effective dose

If It Doesn't Work

• Increase dose, or discontinue and change to another agent

Best Augmenting Combos for Partial Response or Treatment-Resistance

• May try adding D2 antagonist, NK1 antagonist, antihistamine, benzodiazepine, or corticosteroid

Tests

• None required

ADVERSE EFFECTS (AEs)

How the Drug Causes AEs

• Blocking of 5-HT3 receptors

Notable AEs

• Headache, flushing, arrhythmia, urticaria, constipation, fever

• Transient blurred vision, elevated hepatic function tests

Life-Threatening or Dangerous AEs

• Hypersensitivity

• QTc prolongation

Weight Gain

• Unusual

Sedation

• Unusual

What to Do About AEs

• Reduce dose or discontinuation

Best Augmenting Agents to Reduce AEs

• Symptomatic management

DOSING AND USE

Usual Dosage Range

• 8–32mg

Dosage Forms

• Tablets: 4, 8, 16, 24mg

• Orally disintegrating tablet: 4, 8mg

• Film: 4, 8mg

• Injection: 2mg/mL, 4mg/5mL, 32mg/50mL

How to Dose

• For chemotherapy-induced nausea/ vomiting: 8–32mg IV or orally 15–30 minutes before chemotherapy

• Before anesthesia induction: 4mg IV undiluted over 2–5 minutes

Dosing Tips

• Should be administered 30 minutes before emetogenic cancer chemotherapy; 1–2 hours before radiotherapy; or 1 hour before induction of anesthesia

Overdose

• Sudden blindness of 2–3 minutes, hypotension, or vasovagal episode has been reported

Long-Term Use

• No long-term side effect

Habit Forming

• No

How to Stop

• No need to taper

Pharmacokinetics

• Metabolized predominantly by CYP3A4. Half-life 3–6 hours