Source: FDA, National Drug Code (US) Revision Year: 2020
HICON is contraindicated in:
Sodium iodide I 131 may cause thyroiditis with release of thyroid hormone, which may aggravate hyperthyroidism and thyrotoxic cardiac disease [see Adverse Reactions (6)]. When treating hyperthyroidism, consider pre-treatment anti-thyroid medication to help deplete the thyroid hormone. Discontinue the anti-thyroid therapy three days before administration of sodium iodide I 131 [see Drug Interactions (7)]. Consider a beta-blocker pre or post-treatment to minimize the risk of hyperthyroidism and thyroid storm.
The thyroiditis may cause gland enlargement resulting in tenderness and swelling of the neck, pain on swallowing, sore throat, and cough; which may occur approximately the third day after sodium iodide I 131 administration. Consider management with pain-reliever or anti-inflammatory medications.
Sodium Iodide I 131 may cause radiation induced toxicities [see Adverse Reactions (6)]:
Obtain a complete blood count within one month of therapy. If patients show leukopenia or thrombocytopenia, dosimetry should be used to determine a safe sodium iodide I 131 activity, while delivering less than 2 Gy to the bone marrow.
Advise good hydration for one week following sodium iodide I 131 administration and stimulate salivary flow via a sialagogue (e.g. sugar-free candy or gum, pilocarpine, and ascorbic acid) to reduce radiation exposure to the salivary glands.
Advise patients to void frequently after administration of radioiodide to enhance excretion.
Hypersensitivity reactions including anaphylaxis may occur in patients who receive sodium iodide I 131. Although iodide is not considered an allergen, hypersensitivity reactions may occur in relation with excipients or chemical component of the capsule, such as sodium thiosulfate. Obtain and document an allergy history, particularly a sulfite allergy. Emergency resuscitation equipment and personnel should be immediately available [see Adverse Reactions (6)].
HICON is contraindicated in pregnancy because sodium iodide I 131 crosses the placenta and fetal exposure can lead to neonatal hypothyroidism. Multiple reports in the published literature describe hypothyroidism in the neonates following in utero exposure to sodium iodide I 131. Some cases of neonatal hypothyroidism were severe and irreversible. Verify pregnancy status of females of reproductive potential prior to initiating HICON treatment. Advise females and males of reproductive potential to use effective contraception during treatment with HICON and for at least six months after the last dose [see Use in Specific Populations (8.1, 8.3)].
HICON is contraindicated in lactating women because sodium iodide I 131 concentrates in the breast via the increased expression of the sodium iodide symporter in breast tissue with lactation. The literature describes moderate to marked radioiodine uptake in the breast tissue for 5-32 weeks post cessation of breast feeding. Advise lactating women to discontinue breast feeding at least 6 weeks prior to administration of sodium iodide I 131 to allow sufficient time for involution to occur and to avoid excess concentration of sodium iodide I 131 in breast tissue. Consider administration of drugs to suppress lactation. Consider diagnostic scintigraphy before administration of sodium iodide I 131 to assess the persistence of uptake by breast tissue. If sodium iodide I 131 is administered in the postpartum period, the lactating mother should not breastfeed the infant [see Use in Specific Populations (8.2)].
Transient dose-related impairment of testicular function in men and transient ovarian insufficiency in women has been reported after sodium iodide I 131 therapy. Consider sperm banking for men who are anticipated to receive cumulative sodium iodide I 131 doses greater than 19,000 MBq (520 mCi) [see Use in Specific Populations (8.3)].
Instruct patients to follow radiation safety precautions after receiving HICON to minimize the radiation contamination of other persons or the environment. Patients should avoid close contact with others, especially pregnant women and children, and take care to avoid contamination of other persons or the environment with body fluids.
HICON contributes to a patient’s overall long-term cumulative radiation exposure, which is associated with an increased risk of cancer. Follow safe handling and administration to minimize radiation exposure to the patient and healthcare providers.
Certain food or drugs may alter the thyroid uptake of sodium iodide I 131 and diminish its effectiveness. Recent intake of stable iodide in any form, or the use of thyroid or anti-thyroid drugs may diminish thyroid uptake of sodium iodide I 131 [see Drug Interactions (7)].
The following serious adverse reactions are described below and elsewhere in labeling:
The following adverse reactions have been identified during post-approval use of sodium iodide I 131. Because these reactions are voluntarily reported by from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.
* In patients with iodide-avid brain metastases
** In patients with iodide-avid lung metastases
Table 3. Pharmaceuticals/OTCs/Agents Blocking Radioiodine Uptake:
| Type of Medication | Recommended time of withdrawal |
|---|---|
| Thionamide medications (e.g., propylthiouracil, methimazole, carbimazole) | 3 days |
| Multivitamins containing iodide | 10 days |
| Natural or synthetic thyroid hormones triiodothyronine thyroxine | 2 weeks 4 weeks |
| Iodide-containing foods: iodized salt, dairy products, egg yolks, seafood, turkey and liver | 2 weeks |
| Kelp, agar, carrageenan, Lugol solution | 3 weeks |
| Saturated solution of potassium iodide | 3 weeks |
| Topical iodide (e.g., surgical skin preparation) | 3 weeks |
| Intravenous radiographic contrast agents Water soluble Lipophilic | 2 months 6 months |
| Amiodarone | 6 months |
HICON is contraindicated in pregnancy because fetal exposure can lead to neonatal hypothyroidism, which in some cases is severe and irreversible. Data from the published literature describe thyroid abnormalities after fetal exposure; including agenesis of the thyroid and hypothyroidism (see Data). No animal reproductive studies have been conducted.
A fetus exposed to sodium iodide I 131 can develop neonatal hypothyroidism. Delay in diagnosis of neonatal hypothyroidism after exposure to sodium iodide I 131 in utero can result in severe sequelae such as decreased mental capacity and delayed bone age. Monitor thyroid function in any infant born after in utero exposure to sodium iodide I 131.
Sodium iodide I 131 crosses the placenta and the fetal thyroid begins to concentrate iodide during the 10-12th week of gestation. In literature reports of maternal exposures to sodium iodide I 131 at doses of 333–8325 MBq (9–225 mCi) during 4-26 weeks gestational age, the most common adverse outcomes were hypothyroid infants and children.
HICON is contraindicated during lactation because I 131 concentrates in the breast during lactation via the increased expression of the sodium iodide symporter in breast tissue [see Warnings and Precautions (5.5)]. If sodium iodide I 131 is administered in the postpartum period, the lactating mother should not breastfeed. In addition, to minimize the absorbed radiation dose to the breast tissue, breastfeeding and breast-pumping should be discontinued for at least 6 weeks before administration of sodium iodide I 131 (see Data). Women may breast feed with the birth of another child.
Infants exposed to sodium iodide I 131 through breast milk are at risk for development of hypothyroidism because sodium iodide I 131 is distributed into breast milk and may reach concentrations equal to or greater than concentrations in maternal plasma (see Data).
Limited published literature describes sodium iodide I 131 transfer into breast milk and thyroidal uptake by the breastfed infant. The amount of sodium Iodide I 131 detected in the breast milk at 36-48 hours after administration is 1-27% of the injected dose (with injected doses between 1.1–5143 MBq).
HICON is contraindicated in pregnancy because of the risk of fetal hypothyroidism [see Use in Specific Populations (8.1)].
Obtain a pregnancy test in females of reproductive potential and verify the absence of pregnancy before initiating treatment [see Dosage and Administration (2.2), Warnings and Precautions (5.4)].
Advise females and males of reproductive potential to use effective contraception during treatment with HICON and for at least six months after the last dose of HICON.
Fertility may be impaired with HICON treatment. Transient amenorrhea and ovarian insufficiency have been observed after sodium iodide I 131 therapy in females. The literature describes reports of transient menstrual cycle irregularities, including amenorrhea, and ovarian failure in females treated with cumulative doses of 1000–59,000 MBq (27–1594 mCi) sodium iodide I 131.
Fertility may be impaired with HICON treatment. Discuss sperm banking for males who are expected to receive a high cumulative dose of sodium iodide I 131. Transient dose-related impairment of testicular function after sodium iodide I 131 therapy has been reported in the published literature. The literature describes reports of males treated with sodium iodide I 131 at doses of 370 MBq–22,000 MBq (10–595 mCi) resulting in transiently impaired testicular function (including spermatogenesis). Permanent impairment is described with high cumulative doses ranging from 19,000–29,000 MBq (520–800 mCi).
Safety and efficacy in pediatric patients have not been established. Pediatric patients are at an increased lifetime risk for malignancy from radiation exposure.
Clinical experience has not identified differences in safety or effectiveness in geriatric patients compared to younger patients. However, elderly patients are more likely to have decreased renal function and radiation exposure is greater in patients with impaired renal function [see Use in Specific Populations (8.6), Clinical Pharmacology (12.3)].
HICON is primarily excreted by the kidneys. Renal function impairment decreases excretion of sodium iodide I 131 and increases the radiation exposure and risk of radiation toxicity. For patients with a history of renal impairment, evaluate renal function for therapeutic planning and consider dosimetry. Sodium Iodide I 131 is dialyzable. Hemodialysis can be used to reduce total body radiation exposure [see Clinical Pharmacology (12.3)].
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