Ondansetron, Aprepitant

[Cheryl Laubacher]

Hello.
I have a patient asking if aprepitant or ondansetron are acceptable to use since she just found out she's pregnant, although LMP not known. Her situation is complicated by GERD, poor weight gain in adolescent/adult, cyclic vomiting syndrome.
She also uses promethazine, which I know has more experience and accepting use in pregnancy.
Thank you for your advice,
Cheryl Maslouski, RPh, PharmD, BCACP

[kaytlin]

Hi Dr. Maslouski,

Promethazine and ondansetron are commonly used for pregnancy-induced nausea and vomiting. Ondansetron is typically delayed until 6-8 weeks of gestation as there is a marginally increased risk of cleft lip/palate. After the palate completes organogenesis, this is no longer a concern.

There isn't much data available on aprepitant in pregnancy. Its molecular weight (534) is low enough that transfer across the placenta, but high protein binding will probably limit the degree of transfer. Animal studies haven't observed fetal harm. After the utility of ondansetron and promethazine have been exhausted, it would be reasonable to use at the lowest dose for the shortest time to treat this mom.

Kaytlin Krutsch, PharmD, MBA, BCPS