Rare Pregnancy Problem Linked to Thiopurines, FDA Says

Use of thiopurines has been linked with a rare risk of intrahepatic cholestasis of pregnancy (ICP), primarily in patients taking the drugs for inflammatory bowel disease or lupus, the FDA said in a communication to health providers this week.

“Pregnant patients should stop using thiopurines if they develop ICP,” the agency stated.

ICP impairs the normal release of bile and often manifests as intense itching on the hands and feet. It can bring serious consequences, such as preterm birth, lung problems in the offspring from breathing in meconium, or stillbirth.

Thiopurines, a class of immunosuppressants, are known to carry risks for liver toxicity and labeling for the drugs warns of potential fetal harm if used in pregnancy.

The ICP cases associated with the drugs — which include azathioprine, 6-mercaptopurine, and 6-thioguanine — have mainly been in patients with Crohn’s disease, ulcerative colitis, or systemic lupus erythematosus, conditions for which the drugs are not approved but are commonly used.

“The American Gastroenterological Association and the American College of Rheumatology have published treatment guidelines indicating that azathioprine or 6-mercaptopurine may be appropriate to continue on an individualized basis for management of some immunologic conditions during pregnancy,” the FDA stated.

FDA said it will now require new labeling on azathioprine, 6-mercaptopurine, and 6-thioguanine to warn of the risk of ICP and to note that: postmarketing cases of ICP have been reported in patients on thiopurines, ICP symptoms and elevated bile acid levels have been shown to improve after discontinuation of azathioprine, and patients should discontinue use of the immunosuppressants if ICP develops.

As always, providers and patients can report adverse events related to the use of any drugs to MedWatch, the FDA noted.

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