Iobenguane ¹²³I

Risk Summary

Radioactive iodine products cross the placenta and can permanently impair fetal thyroid function. Administration of an appropriate thyroid blocking agent is recommended before use of iobenguane ¹²³I in a pregnant woman to protect the woman and fetus from accumulation of ¹²³I.

There are no available data on iobenguane ¹²³I use in pregnant women to evaluate for a drug-associated risk of major birth defects, miscarriage or adverse maternal or fetal outcomes. Animal reproduction studies have not been conducted with iobenguane ¹²³I. All radiopharmaceuticals have the potential to cause fetal harm depending on the fetal stage of development and the magnitude of the radiation dose. Advise pregnant women of the potential risks of fetal exposure to radiation doses with administration of iobenguane ¹²³I.

The estimated background risk of major birth defects and miscarriage for the indicated population(s) is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively.

Risk Summary

Iodine 123 (¹²³I), radionuclide, is present in human milk. There is no information on the effects on the breastfed infant or on milk production. Advise a lactating woman to interrupt breastfeeding and pump and discard breastmilk for at least 6 days (>10 physical half-lives) after iobenguane ¹²³I administration in order to minimize radiation exposure to a breastfed infant.

Iobenguane hemisulfate was not mutagenic in vitro in the Ames bacterial mutation assay and in the in vitro mouse lymphoma test, and was negative in the in vivo micronucleus test in rats.

Long-term animal studies have not been conducted to evaluate iobenguane ¹²³I’s carcinogenic potential or potential effects on fertility.

Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

During clinical development 1346 patients were exposed to iobenguane ¹²³I, 251 patients with known or suspected pheochromocytoma or neuroblastoma, 985 patients with heart failure, and 110 control patients. All patients were monitored for adverse reactions over a 24 hour period following iobenguane ¹²³I administration.

Pheochromocytoma and Neuroblastoma

Serious adverse reactions were not observed in the iobenguane ¹²³I clinical study. Adverse reactions were all mild to moderate in severity and were predominantly isolated occurrences (≤2 patients) of one of the following reactions: dizziness, rash, pruritus, flushing or injection site hemorrhage.

Congestive Heart Failure

No serious adverse reactions to iobenguane ¹²³I were observed in clinical studies. Adverse reactions that occurred with a frequency >1% were associated with the injection site (1.3%), problems such as hematoma and bruising. The other most common reactions were flushing (0.3%) and headache (0.4%). The adverse reactions were predominantly of mild to moderate intensity.

Postmarketing Experience

Because postmarketing reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

Hypersensitivity reactions have uncommonly been reported during the postmarketing use of iobenguane ¹²³I.