Sodium Iodide I 131 – FDA prescribing information, side effects and uses

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Sodium Iod >Dosage Form: oral solution, concentrate

Medically reviewed by Drugs.com. Last updated on Oct 1, 2018.

Disclaimer: This drug has not been found by FDA to be safe and effective, and this labeling has not been approved by FDA. For further information about unapproved drugs, click here.

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1 INDICATIONS AND USAGE

Sodium Iodide I-131 is indicated for the treatment of hyperthyroidism and selected cases of thyroid carcinoma.

Sodium Iod >

Radiation Safety

1. Sodium Iod >[see Warning and Precautions (5.7)]
2. Use only by, or under the direction of, physicians who are qualified by specific training and experience in the safe use and handling of radioactive materials, and whose experience and training have been approved by the appropriate governmental agency authorized to license the use of radiopharmaceuticals.
3. Use waterproof gloves when handling and administering the product.
4. Maintain adequate shielding during the life of the product.
5. Measure patient dose with a suitable radioactivity calibration system immediately prior to administration.

Important Administration Instructions

  • Do not directly administer the concentrated Sodium Iod >[see Dosage and Administration (2.4)] .
  • Obtain a pregnancy test in females of reproductive potential prior to administration to verify the absence of pregnancy [see Contraindications (4) and Use in Specific Populations (8.1,8.3)] .
  • Instruct patients to fast at least 2 hours before and 2 hours after administration to ensure absorption.
  • Instruct patients to hydrate before and after administration of Sodium Iod >[see Warnings and Precautions (5.2)] .
  • Instruct patients to maintain a low-iod >[see Warnings and Precautions (5.8) and Drug Interactions (7)] .
  • Instruct patients to discontinue the anti-thyro >[see Warnings and Precautions (5.8) and Drug Interactions (7)] .
  • For patients with a history of renal impairment, evaluate renal function for therapeutic planning and cons >[see Use in Specific Populations (8.6)] .
  • 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 Iod >[see Warnings and Precautions (5.2)] .

Recommended Dosage and Administration

Individualization of Therapy
The recommended dose for orally administered Sodium Iodide I 131 capsules or solution is based on the thyroid gland uptake as well as the size of the gland. Thyroidal uptake and size should be determined by the physician prior to treatment and may be useful in calculating the therapeutic dose to be administered to the individual patient.

Treatment of Hyperthyroidism
The recommended dose is 148 to 370 MBq (4 to 10 mCi) administered orally. Toxic nodular goiter may require a larger dose.

Treatment of Thyroid Carcinoma
The recommended dose is 1100 to 3700 MBq (30 to 100 mCi) administered orally. For subsequent ablation of metastases, the recommended dose is 3700 to 7400 MBq (100 to 200 mCi) administered orally.

Dilution and Preparation Instructions

Preparation of Dilute Sodium Iodide I 131 Solution

1. Using the calibration date and radionuclidic concentration on the label of the product vial, calculate the required volume to produce the necessary dose in MBq or mCi.

2. Using a shielded syringe, remove the required volume.

3. Using the shielded syringe, transfer the required volume to a suitably shielded receiving vial.

4. Add diluent to the receiving vial to produce a final dose of the desired volume.

5. The recommended diluent is Purified Water with 300 mg of sodium phosphate dibasic anhydrous dissolved in the water. Acidic diluents should not be used as they may cause the pH to drop below 7.5 and stimulate the volatilization of Iodine I-131 hydriodic acid.

6. Present the dose in a shielded container for administration to the patient with a straw.

Preparation of Sodium Iodide I 131 Capsules

1. Use one large #1 empty gelatin capsule and one small #2 gelatin capsule for each dose to be prepared. Each large capsule is empty and each small capsule should contain approximately 300 mg of dibasic sodium phosphate anhydrous as the absorbing buffer.

2. Using the calibration date and radionuclidic concentration on the label of the sodium iodide I-131 lead shield, calculate the required volume to produce the necessary dose in MBq or mCi.

3. Open the larger #1 capsule by pulling apart the capsule into two pieces as illustrated below:


4. Insert an unopened small #2 capsule containing 300 mg of sodium phosphate dibasic anhydrous powder into the bottom half of the empty large capsule as illustrated below:

5. With an appropriate syringe, withdraw the required volume of Sodium Iodide I 131 Solution (maximum 150 microliters) from the vial as illustrated below:

6. Inject into the center of the small capsule through the top as illustrated below:

7. Slip the upper half of the large capsule over the bottom half to completely cover the small capsule and push down gently until locked as illustrated below:

8. Measure the patient dose in a suitable radioactivity calibration system immediately prior to administration.

9. Prepared capsules may be stored in a suitable polypropylene container and place inside a lead pot until use, within seven days.

Radiation Dosimetry

    The biokinetic modeling and radiation dose distributions associated with thyro >

    Table 1 *

    Blocked thyroid
    (0% A 0 )

    Low uptake †
    (16% A 0 )

    Medium uptake †
    (26% A 0 )

    High uptake †
    (36% A 0 )

    * Table 1 is not intended for treatment planning. † These columns are not applicable to estimate organ or effective doses in patients following thyroidectomy. In patients with thyroid cancer following thyroidectomy, organ and effective doses can be estimated from the “blocked”-thyroid-uptake values. ‡ These values presume unimpeded production of thyroid hormone and may not be applicable to estimate thyroid dose and effective dose in patients who have had previous treatment with I 131 for hyperthyroidism
    Absorbed dose per unit activity Sodium Iodide I 131 administered orally (mGy/MBq) in adult (73.7-kg reference model)
    Organ Thyro >0 )
    24 h after oral administration
    Adrenals 0.044 0.051 0.055 0.059
    Bone surfaces 0.089 0.12 0.16
    Brain 0.021 0.093 0.13 0.17
    Breast 0.020 0.038 0.048 0.058
    Gallbladder wall 0.037 0.043 0.046 0.049
    Gastrointestinal tract
    Esophagus 0.024 0.10 0.14 0.19
    Stomach wall 0.87 0.77 0.71 0.66
    Small intestine wall 0.035 0.033 0.032 0.032
    Colon wall 0.14 0.14 0.14 0.14
    (Upper large intestine wall) 0.12 0.12 0.12 0.12
    (Lower large intestine wall) 0.17 0.17 0.17 0.16
    Heart wall 0.062 0.089 0.10 0.12
    Kidneys 0.27 0.27 0.27 0.27
    Liver 0.050 0.093 0.12 0.14
    Lungs 0.053 0.10 0.13 0.15
    Muscles 0.026 0.084 0.12 0.15
    Ovaries 0.038 0.037 0.036 0.035
    Pancreas 0.060 0.064 0.066 0.068
    Red marrow 0.031 0.072 0.095 0.12
    Salivary glands 0.27 0.22 0.19 0.16
    Skin 0.019 0.043 0.057 0.071
    Spleen 0.064 0.069 0.072 0.075
    Testes 0.025 0.024 0.023 0.22
    Thymus 0.024 0.10 0.14 0.19
    Thyroid 2.2 280 ‡ 430 ‡ 580 ‡
    Urinary bladder wall 0.54 0.45 0.39 0.34
    Uterus 0.045 0.042 0.040 0.038
    Remaining organs 0.029 0.084 0.11 0.15
    Effective dose per administered activity (mSv/MBq) 0.28 14 ‡ 22 ‡ 29 ‡

    Dosage Forms and Strengths

    Sodium Iodide I-131 solution componentis available in customer ordered vials available in 1, 2, 3 and 5 mL V-Vials and 2 and 5 mL Serum Vials containing colorless, aqueous concentrated sodium iodide I-131 with strengths ranging between 18.5 – 129.5 GBq/mL (500 – 3500 mCi/mL) referenced to calibration time for the preparation of sodium iodide I-131 capsules, therapeutic or sodium iodide I-131 solution, therapeutic.

    Contraindications

    Sodium Iodide I-131 is contraindicated in:

    Warnings and Precautions

    Radiation-induced Thyro >Sodium Iod >[see Adverse Reactions (6)] . When treating hyperthyro >[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.

    Radiation-induced Toxicities

    • Dose-dependent fatalities (bone marrow suppression, malignancy).
    • Dose-dependent hematopoietic suppression which manifests as a transient thrombocytopenia or neutropenia 3-5 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.

    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

    Hypersensitivity reactions including anaphylaxis may occur in patients who receive Sodium Iod >[see Adverse Reactions (6)] .

    Fetal Toxicity

    Increased Radiation Exposure to Breast Tissue with Lactation

    Transient Infertility

    Transient dose-related impairment of testicular function in men and transient ovarian insufficiency in women has been reported after Sodium Iod >[see Use in Specific Populations (8.3)] .

    Risk of Radiation Exposure

    Household Contacts
    Instruct patients to follow radiation safety precautions after receiving Sodium Iodide I-131 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
    Sodium Iodide I-131 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.

    Risk of Decreased Effectiveness of Therapy

    Certain food or drugs may alter the thyro >[see Drug Interactions (7)] .

    Adverse Reactions

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

    • Gastrointestinal disorders: sialadenitis, salivary gland dysfunction, nausea, vomiting, gastritis.
    • Cardiac disorders: chest pain, tachycardia.
    • Skin and subcutaneous tissue disorders: itching, rash, hives.
    • Endocrine disorders: hypothyroidism, hyperthyroidism, thyrotoxic crisis, hypoparathyroidism
    • General disorders and administration site conditions: local swelling of thyroid or sites of iodide avid tumor.
    • Hematologic and lymphatic disorders including fatalities: bone marrow depression, anemia, leukopenia, thrombocytopenia, and blood dyscrasia.
    • Neoplasms benign, malignant and unspecified (including cysts and polyps): acute leukemia, solid cancer.
    • Eye disorders: lacrimal gland dysfunction.
    • Congenital, familial and genetic disorders: congenital hypothyroidism, chromosomal abnormalities.
    • Immune system disorders: bronchospasm.
    • Nervous system disorders: headache, *cerebral edema.
    • Respiratory, thoracic and mediastinal disorders: **radiation pneumonitis, **pulmonary fibrosis.

    * In patients with iodide-avid brain metastases
    ** In patients with iodide-avid lung metastases

    Drug Interactions

    • Concomitant use of bone marrow depressants may enhance the depression of the hematopoietic system caused by the use of large doses of Sodium Iod >[see Warnings and Precautions (5.2)] .
    • Many drugs and iod >[see Warnings and Precautions (5.8)] .
    • Advise patients to maintain a low-iod >
      Table 2 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
      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
      Amiodarone 6 months

      USE IN SPECIFIC POPULATIONS

      Risk Summary
      Sodium Iod >Data ). No animal reproductive studies have been conducted.

      Clinical Considerations .
      Fetal/ Neonatal Adverse Reactions
      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.

      Data
      Human Data
      Sodium Iod >th 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.

      Risk Summary
      Sodium Iod >[see Warnings and Precautions (5.5)] . If Sodium Iod >Data ). Women may breast feed with the birth of another child.

      Infants exposed to Sodium Iod >Data ).

      Data
      Human 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).

      Females and Males of Reproductive Potential

      Pregnancy Testing
      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) ].

      Contraception
      Advise females and males of reproductive potential to use effective contraception during treatment with Sodium Iodide I-131 and for at least six months after the last dose of Sodium Iodide I-131.

      Infertility
      Females
      Fertility may be impaired with Sodium Iodide I 131 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.

      Males
      Fertility may be impaired with Sodium Iodide I 131 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).

      Pediatric Use

      Safety and efficacy in pediatric patients have not been established. Pediatric patients are at an increased lifetime risk for malignancy from radiation exposure

      Geriatric Use

      Renal Impairment

      Overdosage

      In case of exposure to a radioactive dose of Sodium Iodide I 131 exceeding the intended therapeutic dose, provide general supportive care, promote frequent voiding, monitor for bone marrow and thyroid suppression. Consider administering a thyroid blocking agent (e.g. potassium iodide (KI) or perchlorate) promptly within 4 to 6 hours after the exposure. Assess the benefit of administering a thyroid blocking agent against the risk of failure of Sodium Iodide I 131 therapy. Appropriate replacement therapy is recommended if hypothyroidism occurs.

      Sodium Iod >The concentrated Sodium Iodide I 131 solution is available in strengths ranging from 18.5 – 129.5 GBq/mL (500 – 3500 mCi/mL) and is used for the preparation of Sodium Iodide I 131 capsules or Sodium Iodide I 131 solution of varying strengths for oral administration for therapy. Each mL of the concentrated solution contains the labeled amount of no carrier added Sodium Iodide I 131 formulated in 0.05M sodium hydroxide with 0.02M sodium thiosulfate added as a stabilizer. The sodium hydroxide maintains the pH above 7.5 to avoid the formation of volatile HI, and the sodium thiosulfate serves as a reducing agent. The pH of the Sodium Iodide I 131 solution is greater than 7.5.

      Sodium Iod >131 I and has a molecular weight of 153.99.

      Physical Characteristics

      Iodine I-131 decays by beta emission and associated gamma emission with a physical half-life of 8.025 days. The principal radiation emissions are listed in Table 3.

      Table 3 Principal Radiation Emission Data from Decay of Sodium Iodide I 131

      Radiation Mean % per
      Disintegration
      Mean Energy
      (keV)
      Beta-1 2.1% 69.4
      Beta-3 7.2% 96.6
      Beta-4 89.4% 191.6
      Gamma-7 6.1% 284.3
      Gamma-14 81.2% 364.5
      Gamma-18 7.1% 637.0

      External Radiation

      The specific gamma-ray constant for iod >-13 C·m 2 ·kg -1 ·MBq -1 ·s -1 (2.2 R·cm 2 /mCi·hr). The first half-value thickness of lead (Pb) for iodide I 131 is 0.27 cm. A range of values for the relative attenuation of the radiation emitted by iodide I 131 that results from interposition of various thicknesses of Pb is shown in Table 4. For example, the use of 2.59 cm of Pb will decrease the external radiation exposure by a factor of about 1,000.

      Shield Thickness
      (Pb) cm

      Coefficient of Attenuation 0.27 0.5 0.56 0.25 0.99 10 -1 2.59 10 -2 4.53 10 -3

      To correct for physical decay of iodine I 131, the fractions that remain at selected intervals after the time of calibration are shown in Table 5.

      Table 5 Physical Decay Chart: Iodine I-131 Half-Life 8.025 days

      *Calibration time
      Days Fraction Remaining Days Fraction Remaining Days Fraction Remaining
      0* 1.000 11 .388 22 .151
      1 .918 12 .356 23 .138
      2 .842 13 .327 24 .127
      3 .773 14 .300 25 .116
      4 .709 15 .275 26 .107
      5 .651 16 .253 27 .098
      6 .597 17 .232 28 .090
      7 .548 18 .213 29 .083
      8 .503 19 .195 30 .076
      9 .461 20 .179
      10 .423 21 .164

      Sodium Iod >

      Mechanism of Action

      Iod >+ ) which in turn iodinates tyrosine residues of thyroglobulin (tri or tetra-iodinated tyrosine). The beta emission of I 131 is responsible for the therapeutic effect.

      Pharmacodynamics

      The relationship between the extent of iodide I 131 exposure and pharmacologic effects has not been explored in clinical trials.

      Pharmacokinetics

      Absorption
      Following oral administration of Sodium Iodide I 131, 90% of the administered radioactivity of Iodide I 131 is systemically absorbed in the first 60 minutes.

      Distribution
      Following absorption, I 131 is distributed within the extra-cellular space. It is actively transported by the sodium-iodide symporter (NIS) protein, and binds to thyroglobulin resulting in accumulation in the thyroid. The thyroid uptake of iodide is usually increased in hyperthyroidism and in goiter, and is decreased in hypothyroidism. Sodium Iodide I 131 also accumulates in the stomach, choroid plexus, salivary glands, breast, liver, gall bladder, and kidneys.

      Elimination
      Metabolism
      In thyro >+ ) which in turn iodinates tyrosine residues of thyroglobulin.

      Excretion
      Sodium Iodide I 131 is excreted in urine and feces. The normal range of urinary excretion is 37% to 75% of the administered dose, varying with the thyroid and renal function of the patient. Fecal excretion is about 10%.

      How Supplied/Storage and Handling

      How Supplied

      The Sodium Iodide I-131 Solution can be supplied in any of the following vials: 1, 2, 3 and 5 mL clear glass V-Vials and in 2 and 5 mL serum vials.The strength is specified by the customer from 18.5 to 129.5 GBq/mL (500 to 3500 mCi/mL) at time of calibration.

      Kit for Preparation of Sodium Iodide I-131 Capsules and Solution

      NDC Code Size/Type Container
      69208-005-15 1 mL V-vial
      69208-005-25 2 mL V-vial
      69208-005-35 3 mL V-vial
      69208-005-55 5 mL V-vial
      69208-005-60 2 mL Serum vial
      69208-005-70 5 mL Serum vial

      The Sodium Iodide I-131 should be stored between 2°C and 25°C (36°F and 77°F). Store and dispose of Sodium Iodide I 131 in compliance with the appropriate regulations of the government agency authorized to license the use of this radionuclide.

      Discard unused capsules after all Sodium Iodide I 131solution has been dispensed or expired. New blister packages of hard gelatin capsules are provided with each new shipment of Sodium Iodide I-131 Solution.

      This radiopharmaceutical is approved for use by persons under license by the Nuclear Regulatory Commission or the relevant regulatory authority of an Agreement State.

      Patient Counseling Information

      Radiation Safety Precautions [see Warnings and Precautions (5.7)] .
      Review the most recent professional society guidelines and publications that describe important components of the patient counseling process and discuss measures to minimize inadvertent radiation exposure to the patient.

      • Advise female patients of the risk to a fetus.
      • Advise females and males of reproductive potential to use effective contraception during treatment with Sodium Iodide I 131 and for at least 6 months after the last dose.
      • Advise female patients to contact their healthcare provider with a known or suspected pregnancy.

      Lactation
      • Instruct women to stop breastfeeding and breast-pumping at least 6 weeks prior to Sodium Iod >[see Contraindications (4), Warnings and Precautions (5.5) and Use in Specific Populations (8.2)].

      Effects on Fertility
      • Advise females and males of reproductive potential of the potential for impaired fertility with Sodium Iod >[see Warnings and Precautions (5.6) and Use in Specific Populations (8.3)].

      Manufactured by:
      International Isotopes Inc., Idaho Falls, Idaho 83401, USA

      PRINCIPAL DISPLAY PANEL

      Sodium Iodide I-131 Solution Immediate Container Label

      Sodium Iodide I-131 Solution – Lead Shield Label

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