5-HT3 Antagonists

Question 1

Mechanism of action ?

Answer 1

A vomiting center in the medulla receives signals from : CTZ, solitary tract nucleus (vague nerve) and the vestibular system. 5-hydroxytriptamine plays a key role in the two first stated pathways.

Question 2

Indications ?

Answer 2

Prophylaxis and treatment of N&V in the context of anesthesia and chemotherapy.

Question 3

Important AE ?

Answer 3

Generally tolerated, but constipation, diarrhea and headaches are a possibility.

Question 4

Important cautions ?

Answer 4

Ought to be avoided in patients with prolonged QT interval (it does that in high doses)

Question 5

Important interactions ?

Answer 5

Ought to be avoided in patients taking drugs that prolong QT interval; antipsychotics, Quinine, SSRI.

Question 6

5-HT3 antagonists ?

Answer 6

Ondansetron

Granisetron

Question 7

Howe are they prescribed ?

Answer 7

Oral, rectal, IV and IM routes are available. typical starting dose of Ondansetron 8-12 mg 12-hrly.

Question 8

Flip for a clinical tip

Answer 8

Ondansetron can be utilized in severe pregnancy morning sickness; hyperemesis gravidum.