1. 5HT3 Receptor Antagonists (not alosetron)

Question 1

MOA of 5-HT3 receptor antagonists

Answer 1

Inhibit 5-hydroxytryptamine-3 receptors; selectively blocks serotonin (an emesis inducer); acts peripherally on vagal nerve terminals; acts centrally in the chemoreceptor trigger zone

Question 2

ondansetron (brand, dosing) - common

Answer 2

Zofran (ODT, IV, IM, PO), Zuplenz (film)
PO: 16-24 mg beginning 30 min before chemo (w/ dexamethasone 12 mg PO/IV x1); 8 mg BID x1-2days after chemo
IV: 8-16 mg

Question 3

palonosetron (brand, dosing) - preferred

Answer 3

Aloxi
PO: 0.5 mg
IV: 0.25 mg

Question 4

dolasetron (brand, dosing)

Answer 4

Anzemet (PO)
100 mg
(IV not indicated for CINV due to QT prolongation risk)

Question 5

granisetron (brand, dosing)

Answer 5

Kytril (IV, PO), Sancuso (patch)
PO: 2 mg
IV: 10 mcg/kg or 1 mg IV
Patch:3.1 mg/24hr patch 24-48 hrs before chemo, leave in place up to 7 days

Question 6

5-HT3 monitoring

Answer 6

Safety: ECG (QT), Mg, K
Efficacy: N/V episodes

Question 7

5-HT3 DDIs

Answer 7

CYP2D6, CYP3A4 (bupropion, aprepitant)
SSRIs, SNRIs (serotonin syndrome)
QT-prolonging drugs (quinolones, SSRIs, TCAs)

Question 8

5-HT3 CIs, SEs

Answer 8

CI: hypersensitivity, concomitant apomorphine
SEs: headache, fatigue, dizziness, constipation, QT-elongation

Question 9

5-HT3 pregnancy category __

Answer 9

B

Question 10

5-HT3 indications

Answer 10

Acute, delayed, breakthrough N/V

Question 11

5-HT3 warnings (2)

Answer 11

–dose-dependent increase in QT interval (more common in IV)

–serotonin syndrome when used in combo with other serotonergic agents