INTERACTIONS Concomitant use of bone marrow depressants may enhance the depression of the hematopoietic system caused by the use of large doses of sodium iodide I 131 [see Warnings and Precautions (5.2 )] . Many drugs and iodide-containing foods interfere with the accumulation of radioiodide by the thyroid. Review the patients history, current medications, and recent diagnostic tests prior to the administration of sodium iodide I 131 [see Warnings and Precautions (5.8) ] . Advise patients to maintain a low-iodide diet two weeks prior to radioiodide administration and continue for several days during the uptake or imaging process and to discontinue taking the following products before they undergo the procedure as shown in Table 4.
Table
4 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 Many drugs and iodine-containing foods interfere with the accumulation of radioiodide by the thyroid. Instruct patients to maintain a low-iodide diet (2 weeks) and discontinue anti-thyroid therapy (3 days) before administration. ( 5.8 , 7 )
HICON ® is contraindicated in: Patients with vomiting and diarrhea [see Warnings and Precautions ( 5.7 )] . Patients with thyroid malignancies shown to have no iodide update, which include the majority of medullary or anaplastic carcinomas. Patients receiving concurrent anti-thyroid therapy [see Warnings and Precautions ( 5.1 ) and Drug Interactions ( 7 )] . Pregnancy [see Warnings and Precautions ( 5.4 ), Use in Specific Populations ( 8.1 )] . Lactation [see Warnings and Precautions ( 5.5 ), Use in Specific Populations ( 8.2 )] . Patients with vomiting and diarrhea. ( 4 ) Patients with thyroid malignancies shown to have no iodide uptake. ( 4 ) Patients receiving concurrent anti-thyroid therapy. ( 4 ) Pregnancy. ( 4 ) Lactation. ( 4 )
AND PRECAUTIONS Radiation-induced thyroiditis may cause or worsen hyperthyroidism. Consider pre-treatment with anti-thyroid medications. ( 5.1 ) Multiple non-thyroid radiation toxicities, including hematopoietic suppression: Individualize dose and monitor for toxicity. ( 5.2 ) Embryo-Fetal toxicity: May cause severe and irreversible hypothyroidism in the neonate. Verify pregnancy status in females of reproductive potential prior to initiating treatment. Females and males of reproductive potential should use effective contraception. ( 5.4 , 8.1 , 8.3 ) Radiation exposure to breast tissue with lactation: Sodium iodide I 131 concentrates in the breast of lactating women. Discontinue breast feeding at least 6 weeks prior to therapy. ( 5.5 , 8.2 )
5.1 Radiation-induced Thyroiditis Sodium iodide I 131 may cause thyroiditis with gland enlargement and release of thyroid hormone, which may cause or aggravate hyperthyroidism, thyroid storm and thyrotoxic cardiac disease <span class="opacity-50 text-xs">[see Adverse Reactions (6) ]</span> . When treating hyperthyroidism, consider pre-treatment anti-thyroid medication to help deplete the thyroid hormone content within the gland. Discontinue the anti-thyroid medication at least three days before administration of sodium iodide I 131 <span class="opacity-50 text-xs">[see Drug Interactions (7) ]</span>. Consider a beta-blocker pre or post-treatment to minimize the risk of hyperthyroidism and thyroid storm. 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.
5.2 Radiation-induced Toxicities Sodium Iodide I 131 may cause radiation induced toxicities <span class="opacity-50 text-xs">[see Adverse Reactions (6) ]</span> : Dose-dependent fatalities (bone marrow suppression, malignancy). Dose-dependent hematopoietic suppression which manifests as a transient thrombocytopenia or neutropenia 3 to 5 weeks following sodium iodide I 131 administrations, may lead to increased susceptibility to infections or bleeding. Salivary gland toxicity: sialadenitis, xerostomia. Lacrimal gland toxicity: conjunctivitis, xerophthalmia, and epiphora. Increased risk of developing new solid tumors and leukemias. 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.
5.3 Hypersensitivity Reactions 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 <span class="opacity-50 text-xs">[see Adverse Reactions (6) ]</span> .
5.4 Embryo-Fetal Toxicity 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 6 months after the last dose <span class="opacity-50 text-xs">[see Use in Specific Populations ( 8.1 , 8.3 )]</span> .
5.5 Increased Radiation Exposure to Breast Tissue with Lactation 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 to 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 <span class="opacity-50 text-xs">[see Use in Specific Populations ( 8.2 )]</span> .
5.6 Transient Infertility Transient dose-related impairment of testicular function in men and transient ovarian insufficiency in women has been reported after sodium iodide I 131 therapy. Sperm banking for men may be considered prior to administration of HICON ® for thyroid carcinoma <span class="opacity-50 text-xs">[see Use in Specific Populations ( 8.3 )]</span>.
5.7 Radiation Exposure to Other Individuals Household Contacts 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. Patients and Healthcare Providers 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.
5.8 Risk of Decreased Effectiveness of Therapy 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 <span class="opacity-50 text-xs">[see Drug Interactions ( 7 )]</span> .