Concerns Over Cardiac Complications With Zofran Use

Some express concern over the article citing possible cardiac complications due to the use of Zofran. However, the risk was stated by the FDA to be in patients given a single dose of 32 mg of intravenous Zofran, which is not done in pregnancy nor for HG. Studies on teratogenicity (ability to cause developmental anomalies in a fetus) of Zofran (ondansetron) have been reassuring although a few recent studies are somewhat conflicting. While safety is not proven for any drug during pregnancy, it appears that any potential risk of Zofran is quite low and needs to be assessed with an understanding of the risk of not using the medication.

Torsade de Pointes

Specifically in regards to this article by Dr. Koren**, it is important to note that the complication cited, Torsade de Pointes, has never been reported associated with ondansetron, and does not appear in the medical research database as occurring in HG mothers. Contrary to the author’s statement, ECG monitoring is not "required" by the FDA, although it is recommended in high risk patients including those with electrolyte abnormalities or preexisting cardiac disorders. It should also be emphasized that the FDA is most concerned about patients receiving a single IV dose of 32 mg of Zofran which is not done for HG. It is important to preventing electrolyte abnormalities and closely monitor women with HG on ondansetron.

[In the interest of full disclosure: Dr. Koren also serves as a paid consultant to Duchesnay Inc. in Blainville, Que. who manufactures Diclegis and Diclectin.]

Serotonin Syndrome

Further, Serotonin Syndrome as mentioned in the article, has never been reported with ondansetron alone, nor has a research paper been published citing its occurrence in HG. Women with HG are rarely on SSRIs (antidepressants) in addition to ondansetron due to inability to tolerate additional medication, but again, awareness of the potential drug interactions is important for prescribers and patients.

Preventing Adverse Reactions

  • Do not administer 32 mg IV.
  • Monitor EKG if abornmal cardiac history.
  • Replace electrolytes and vitamins intravenously.
  • Avoid use with other serotonin antagnoist medications.

Pharmaceutical Trends

NOTE: While it is true that some medications risks cannot be ascertained until the medication is widely used for some time, in the history of antiemetic medications, we have seen this before. A new branded medication gets approved and the risks of older generic medications are highlighted, ultimately limiting rather than expanding the treatment options available for pregnant women with HG. When Zofran was released, this happened to Droperidol, Reglan, and Phenergan. Now that Zofran is no longer on patent and Emend and Diclegis have been released, it seems to be happening with Zofran. We are very concerned that this will have negative effects on the treatment of HG as we are already hearing some medical professionals will no longer prescribe Zofran.

Recommendations for Zofran Usage

The health professionals associated with the HER Foundation fully agree that Zofran (ondansetron) should not generally be used as a first line treatment for nausea in pregnancy, especially before vomiting and weight loss occur in a first time mother. As Dr. Koren has stated previously, in women with a history of HG, we agree that it may be advantageous to use antiemetics (e.g. Zofran) when symptoms begin limiting intake to reduce the severity of symptoms and minimize secondary complications related to dehydration, malnutrition and debility.

We also agree that the risks and potential benefits of any medication use, especially in pregnancy, should be carefully considered prior to use. Our research data of over a 1000 HG mothers finds that ondansetron is most effective for relief of symptoms in HG. Other studies report positive outcomes from Zofran use like preventing therapeutic termination.

We encourage further evaluation of the safety of ondansetron with regards to congenital anomalies and long-term outcomes, however, recent large studies have not found evidence to suggest concern. As its use has greatly increased since the 1990’s in the US, incidence of fetal malformations and complications such as cardiac arrhythmias have not increased in our data or in any other database to our knowledge.

Risks vs Benefits

HG is an extreme form of NVP and the risks of untreated or undertreated HG for both the mother and fetus can be devastating leading even to death or long term disability of either. These clear, reported and well documented risks need to be balanced against any potential (and with ondansetron, unproven, or never reported) risks of any medication or other treatment used to treat the condition. Zofran (ondansetron) remains an important option for the treatment of HG.