Horizant and Pregnancy
When pregnant animals were given Horizant (gabapentin enacarbil) in clinical studies, fetal problems such as kidney problems and delayed bone development were reported. Due to the potential risks, the United States Food and Drug Administration has classified this drug as a pregnancy Category C medication. However, it may still be prescribed to a pregnant woman if the benefits outweigh the risks.
Horizant™ (gabapentin enacarbil) is a prescription medication used to treat restless legs syndrome (RLS) and postherpetic neuralgia. Based on the results of animal studies (which may not reflect the true risks for humans), the drug may not be safe for use during pregnancy.
The U.S. Food and Drug Administration (FDA) uses a category system to classify the possible risks to a fetus when a specific medicine is taken during pregnancy. Pregnancy Category C is given to medicines that have not been studied in pregnant humans but did appear to cause harm to the fetus in animal studies.
In addition, medicines that have not been studied in any pregnant women or animals are automatically given a pregnancy Category C rating.
Studies of gabapentin (the active ingredient in Horizant) in pregnant rodents suggest that Horizant may delay the growth and development of the fetus, especially affecting the bones. When given to pregnant rats, gabapentin caused problems in the kidneys and urinary tract. When given to pregnant rabbits, it increased the risk of miscarriages.
One study in mice has also suggested that gabapentin may have the potential to decrease brain synapse formation, although it is unclear what, if anything, this might mean for human pregnancies.
It is important to note that animals do not always respond to medicines the same way that humans do. Therefore, a pregnancy Category C medicine such as Horizant may be given to a pregnant woman if the healthcare provider believes that the benefits to the woman outweigh any possible risks to the unborn child.