Arcalyst and Pregnancy
When Arcalyst (rilonacept) was given to pregnant animals, it caused abnormalities in fetal bone development. Due to the potential risks, the FDA classified the drug as a pregnancy Category C medicine, meaning it may not be safe for use during pregnancy. However, a healthcare provider may prescribe it during pregnancy when the benefits outweigh the risks.
Can Pregnant Women Use Arcalyst?Arcalyst® (rilonacept) is a prescription medication used in the treatment of a group of hereditary conditions known as cryopyrin-associated periodic syndromes (CAPS). CAPS include familial cold autoinflammatory syndrome (FCAS) and Muckle-Wells syndrome (MWS). Based on the results of animal studies, this medication may harm a developing fetus if used during pregnancy.
What Is Pregnancy Category C?Arcalyst is classified as a pregnancy Category C drug. 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 used during pregnancy. Pregnancy Category C is given to medicines that have not been adequately studied in pregnant humans but have caused fetal harm 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.
Arcalyst has not been studied in pregnant women. However, when the medication was given to pregnant monkeys, it appeared to cause abnormalities in fetal bone development, including the absence of ribs. A similar medicine increased the risk for miscarriage when given to pregnant mice.
However, it is important to note that animals do not always respond to medicines in the same way that humans do. Therefore, a pregnancy Category C medicine, including Arcalyst, may be given to a pregnant woman if her healthcare provider believes that the benefits to the woman outweigh any possible risks to her unborn child.