Kidney malformations represent another birth defect risk associated with the off-label use of Zofran during pregnancy. An interesting Australian research showed discomforting results about the high risk of congenital renal deformities associated with the utilization of ondansetron during the first trimester of gestation, although larger studies are still required to further investigate the issue .
The off-label use in Australia and Canada
Many women who took the antiemetic during their gestational period, later gave birth to malformed children. Among the various congenital defects, however, one of the least investigated was the renal malformation. Ondansetron off-label use is not, in fact, a problem just in the U.S., but in other countries such as Canada and Australia as well. In Canada, an investigative report published in the Toronto Star in 2014 showed alarming results that may shed some light about an underinvestigated risk of kidney defects. Twenty Canadian women who took this medication to suppress vomiting during pregnancy suffered from several serious adverse reactions. Two newborns died before childbirth, and many others suffered from kidney defects and heart malformations 3.
A recent survey performed in Australia found that ondansetron represented 75% of total prescriptions for the treatment of hyperemesis gravidarum, the most severe form of nausea and vomit during pregnancy (NVP) 4. To determine the real risks associated with this widespread use of this antiemetic for the treatment of morning sickness, a group of Australian researchers led an epidemiological study on 251 pregnant women who took it 5.
The results of the Australian study
Probably the most discomforting result showed by the study was the increased risk of stillbirth associated with the use of this medicine in expectant mothers. Women who used the antiemetic showed 1.8 times higher chance of giving birth to a dead baby, but even those children who lived after birth often suffered from other serious malformation or were just sicker than their counterparts. The newborn’s health and physical conditions are usually evaluated by a test called the “APGAR score.” APGAR is an acronym that stands for Appearance, Pulse, Grimace, Activity, and Respiration. Those five parameters are used to evaluate the infant’s condition with a score that goes from 0 to 2 (with 2 meaning a very healthy baby, and 0 a very sick one). The Australian study showed that mothers who took the drug during the first trimester of pregnancy had a two-fold change to give birth to newborns with a very low APGAR score. Findings from the study also showed a 20% increased risk of congenital anomalies, including kidney defects such as the obstructive defects of renal pelvis and ureter, and hydronephrosis.
The effects of renal malformations
The kidney malformations found in the Australian studies can seriously affect the life of a baby through his whole life if left untreated. Kidneys work as “filters” in our body by cleaning our blood from every toxic substance. These organs’ primary role is to remove all the waste from our body that is then eliminated through urines via the genitourinary tract. Any congenital abnormality that could cause a blockage within the path of urine from the kidneys to the bladder, such as an ureteral obstruction, an ureterocele or a vesicoureteral reflux, will prevent urine from being drained properly.
Excess urine is then accumulated in the kidneys or inside the ureters (the tubes that connect kidneys to bladder) causing, respectively, hydronephrosis and hydroureter. Severe forms of hydronephrosis can cause renal failure as the renal function is impaired due to the progressive atrophy of the local tissues. During pregnancy, a reduced kidney output may negatively affect the baby’s growth and proper development of his organs, especially the lungs. After the baby is born, however, an obstructive kidney defect can either cause permanent organ damage, or, at least, increase the risk for chronic and recurrent urinary tract infections (UTI) 6.
Renal malformations can be diagnosed with prenatal ultrasounds or amniocentesis. Treatment usually requires surgical removal of the blockage, and subsequent implantation of a metallic shunt inside the ureters after the baby is born. More severe cases such as complete urine blockage that prevent amniotic fluid from developing may, however, require a surgical intervention during pregnancy.
Article written by: Dr. Claudio Butticè, Pharm.D.
Published: 2016/08/09
Last Updated: 2016/12/27
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