Sodium Iodide I 131 (Systemic—Therapeutic)


VA CLASSIFICATION
Primary: AN600

Commonly used brand name(s): Iodotope.

Note: For a listing of dosage forms and brand names by country availability, see Dosage Forms section(s).



Category:


Antihyperthyroid agent—

antineoplastic—

Indications

Accepted

Hyperthyroidism (treatment)—Sodium iodide I 131 is indicated for the treatment of diffuse toxic goiter (Graves' disease), single or multiple toxic nodular goiter, and recurrent hyperthyroidism following surgical or medical treatment. Sodium iodide I 131 may be used in patients of any age if medically appropriate. {01} {02} {03} {04} {05} {07} {12} {20} {22} {23} {25} {30} {31} {32} {42} {45} {52} {55} {60}

Carcinoma, thyroid (treatment)—Sodium iodide I 131 is indicated for the treatment of functioning metastatic papillary or follicular carcinoma of the thyroid. The amount of sodium iodide I 131 used for the treatment of thyroid carcinoma is variable and depends upon the amount of normal thyroid tissue remaining and the extent of thyroid metastases and the degree to which they accumulate sodium iodide I 131. {01} {03} {07} {20} {21} {22} {30} {42} {45} {52}


Physical Properties

Nuclear data: {01} {20}



Radionuclide
(half-life *)
Decay
constant
Mode of
decay
Principal
emissions
(keV)
Mean number
of emissions/
disintegration
I 131
(8.08 days)
0.00358 h -1
Beta
Beta (191.6)
0.90
      Gamma
(364.5)
0.81
* For therapeutic use: In the hyperthyroid patient, a percent of the administered dose equal to the fractional radioiodide uptake (usually between 35 and 90%) of the administered sodium iodide I 131 is concentrated in the thyroid gland and has an effective half-life of approximately 4 to 6 days. The non-thyroidal sodium iodide I 131 is distributed within the extracellular fluid and has an effective half-life of approximately 0.34 day. {10} {22} {42} {59}


Pharmacology/Pharmacokinetics

Mechanism of action/Effect:

The action of therapeutic radioiodide is based on one of the normal functions of the thyroid gland, which is the accumulation and retention of iodine as required for the synthesis of thyroid hormones. Radioiodide may also be concentrated in papillary, follicular, or mixed papillary/follicular thyroid cancer and metastases, although to a lesser extent than in normal thyroid tissue {42} {59}. When large doses of sodium iodide I 131 are given orally, it is possible to selectively damage or destroy thyroidal tissue as required in the treatment of hyperthyroidism or thyroid carcinoma {01} {03} {07} {16} {22} {42} {59}.

Absorption:

Readily absorbed from gastrointestinal tract {01} {07} {45} {52}.

Distribution:

Selectively concentrated and bound to tyrosyl residues of thyroglobulin in the thyroid gland; also concentrated, but not protein-bound, in the choroid plexus, gastric mucosa, salivary glands, nasal mucosa, and lactating breast tissue, with the remainder being distributed within the extracellular fluid {01} {05} {07} {16} {45} {52}.

Half-life:


Biological (for thyroid compartment):

Euthyroid: 80 days.

Hyperthyroid: 5 to 40 days. {22}


Onset of therapeutic action

Approximately 2 to 4 weeks. {02}

Time to peak therapeutic effect

Approximately 2 to 4 months. {02}

Radiation dosimetry:
{26}

Organ
I 131
Estimated absorbed radiation dose *
Maximum thyroid
uptake (%)
mGy/MBq
rad/mCi
Bladder wall
0
0.61
2.26
  5
0.58
2.15
  15
0.52
1.93
  25
0.46
1.70
  55
0.29
1.07
Uterus
0
0.054
0.20
  5
0.055
0.20
  15
0.054
0.20
  25
0.052
0.19
  55
0.046
0.17
Kidneys
0
0.065
0.24
  5
0.063
0.24
  15
0.060
0.22
  25
0.058
0.21
  55
0.051
0.19
Ovaries
0
0.042
0.16
  5
0.044
0.16
  15
0.043
0.16
  25
0.043
0.16
  55
0.041
0.15
Large intestine
0
0.043
0.16
wall (lower)
5
0.043
0.16
  15
0.042
0.16
  25
0.041
0.15
  55
0.040
0.15
Red marrow
0
0.035
0.13
  5
0.038
0.14
  15
0.054
0.20
  25
0.070
0.26
  55
0.12
0.44
Small intestine
0
0.038
0.14
  5
0.28
1.04
  15
0.28
1.04
  25
0.28
1.04
  55
0.28
1.04
Bone surfaces
0
0.032
0.12
  5
0.032
0.12
  15
0.047
0.17
  25
0.061
0.23
  55
0.11
0.41
Large intestine
0
0.037
0.14
wall (upper)
5
0.059
0.22
  15
0.059
0.22
  25
0.059
0.22
  55
0.058
0.21
Pancreas
0
0.035
0.13
  5
0.050
0.19
  15
0.052
0.19
  25
0.053
0.20
  55
0.058
0.21
Spleen
0
0.034
0.13
  5
0.039
0.14
  15
0.042
0.16
  25
0.044
0.16
  55
0.051
0.19
Adrenals
0
0.037
0.14
  5
0.032
0.12
  15
0.036
0.13
  25
0.039
0.14
  55
0.049
0.18
Testes
0
0.037
0.14
  5
0.029
0.11
  15
0.028
0.10
  25
0.027
0.10
  55
0.026
0.10
Stomach wall
0
0.034
0.13
  5
0.45
1.67
  15
0.46
1.67
  25
0.46
1.67
  55
0.46
1.67
Liver
0
0.033
0.12
  5
0.030
0.11
  15
0.032
0.12
  25
0.035
0.13
  55
0.043
0.16
Lungs
0
0.031
0.11
  5
0.034
0.13
  15
0.053
0.20
  25
0.072
0.27
  55
0.13
0.48
Breast
0
0.033
0.12
  5
0.031
0.11
  15
0.043
0.16
  25
0.055
0.20
  55
0.091
0.34
Thyroid
0
0.029
0.11
  5
72.00
266.67
  15
210.00
777.78
  25
360.00
1333.33
  55
790.00
2925.93
Other tissue
0
0.032
0.12
  5
0.040
0.15
  15
0.065
0.24
  25
0.090
0.33
  55
0.16
0.59
* Data based on the International Commission on Radiological Protection (ICRP) Publication 53—Radiation Dose to Patients from Radiopharmaceuticals. {26}
 Estimates based on intravenous administration. With oral administration there is a radiation dose to the stomach in addition to that due to iodide in gastric and salivary secretions. Assuming a mean residence time in the stomach of 30 minutes, the absorbed dose to the stomach wall is increased by approximately 30% with oral administration, while the dose to organs and tissues other than the stomach wall is not significantly changed. {26}


Effective dose §

 
Maximum Thyroid Uptake (%)
  0
5
15
25
55
mSv/MBq
0.072
2.3
6.6
11
24
rem/mCi
0.27
8.51
24.42
40.7
88.8
 With thyroid blocking, thyroid uptakes ranging from 0.5 to 2.0% will still occur. Under these circumstances, the effective dose to the adult will range from 0.30 to 0.97 mSv/MBq (1.11 to 3.59 rem/mCi) for I 131. {26}
§ The effective dose is virtually identical after oral or intravenous administration. {26}

Elimination:
    Renal—Primary, 50 to 75% of the administered activity eliminated in the urine of euthyroid patients with normal renal function within 48 hours. {01} {07} {42} In patients with thyrotoxicosis, myxedema, or thyroidectomy, the fraction of administered activity eliminated in the urine within 48 hours is 6 to 32%, 72 to 92%, or greater than 95%, respectively {63} {64}.
    Fecal and salivary—Secondary. {01}
    Breast milk—Up to 20% of administered activity appears in the milk within 24 hours. {48}


Precautions to Consider

Carcinogenicity

Experiments in animals with sodium iodide I 131 have demonstrated that radioiodide administration can induce thyroid adenomas and carcinomas. {12} {13} {43} However, studies in humans have shown no conclusive evidence of thyroid carcinoma in hyperthyroid patients treated with sodium iodide I 131. {12} {13} {14} {30} {42} {43}

Also, studies with sodium iodide I 131 have not demonstrated that leukemia occurs more frequently in patients treated with this medication than in other hyperthyroid patients. {12} {13} {14}

Mutagenicity

Mutagenic effects have not been clearly established in clinical studies of patients treated with sodium iodide I 131. However, chromosomal changes have been reported in laboratory studies. {01} {12}

Pregnancy/Reproduction
Fertility—
A follow-up study of 627 women treated for differentiated thyroid carcinoma with sodium iodide I 131 revealed no evidence of fertility impairment. {49}

Pregnancy—
Iodide I 131 crosses the placenta and may cause severe and irreversible hypothyroidism in the neonate; the fetal thyroid begins to concentrate iodine during approximately the 12th week of gestation. Sodium iodide I 131 is contraindicated for the treatment of disease during pregnancy. {01} {03} {06} {12} {20} {30} {42} {43} {46}

To avoid the possibility of fetal exposure to radiation, in those circumstances where the patient's pregnancy status is uncertain, a pregnancy test should be performed and will help to prevent inadvertent administration of this preparation during pregnancy. {11} {42}

Studies have not been done in animals. {45}

FDA Pregnancy Category X. {01} {28} {29} {30} {45} {52}

Breast-feeding

Radioiodide is distributed into breast milk {45} {52} and may reach concentrations equal to or greater than concentrations in maternal plasma. {46} {48} {57} It has been recommended that nursing be resumed after administration of a radiopharmaceutical when the likelihood of the infant's ingested effective dose equivalent (EDE) is below 1 mSv (100 mrem). A method to calculate the EDE has been proposed based on the effective half-life of the radionuclide, the activity administered to the mother, the fraction of administered activity ingested by the infant, and the total body effective dose equivalent to the newborn infant per unit of activity ingested. According to this method, it has been estimated that the time to reduce the EDE to the infant to below 1 mSv (100 mrem) is approximately 10 weeks after administration of 40 megabecquerels (1.08 millicuries) of sodium iodide I 131 to the mother. Because of the difficulty of maintaining the maternal milk supply for such an extended period of time, complete cessation of nursing is usually recommended. {09} {10} {19} {24} {42} {48} Also, to minimize the absorbed radiation dose to the breast tissue and to ensure that mammary secretory activity has ceased {48} {51}, breast-feeding should be discontinued several weeks before starting treatment with sodium iodide I 131. {42}

Pediatrics

There is no conclusive evidence linking carcinogenicity, leukemogenicity, and mutagenicity to radioiodide therapy in children and growing adolescents {20} {42} {46} {59}.

Retrospective studies in children and adolescents treated with sodium iodide I 131 for hyperthyroidism have shown that sodium iodide I 131 is effective for both the initial treatment of hyperthyroidism and in cases in which other treatment modalities have failed. However, the occurrence of vomiting in the early posttreatment period may present management problems in some pediatric patients. {50}


Geriatrics


Geriatric patients with severe thyrotoxic cardiac disease should be given antithyroid agents and/or beta-adrenergic blocking agents, such as propranolol, for 4 to 6 weeks prior to treatment with radioiodide to help reduce possible aggravation of the condition by radiation thyroiditis. Antithyroid drugs must be discontinued at least 3 to 4 days prior to treatment and should not be readministered until 1 week after treatment. However, a beta-adrenergic blocking agent may be used throughout the treatment period if needed. {01} {03} {04} {06} {07} {17} {22}

Drug interactions and/or related problems
The following drug interactions and/or related problems have been selected on the basis of their potential clinical significance (possible mechanism in parentheses where appropriate)—not necessarily inclusive (» = major clinical significance):

Amiodarone or
Antithyroid preparations—thioamide derivatives or aromatic preparations or{03}{04}{07}{17}{20}{22}{30}
Benzodiazepines or{07}
Contrast media, iodinated or{08}{20}
Corticosteroids or{07}{08}{20}
Goitrogenic foods (e.g., cabbage, turnips) or{20}
Iodine-containing foods or{07}{08}{20}
Iodine-containing preparations or{07}{08}{20}
Iodine-contaminated bromides or{20}
Iodine, stable or{20}{30}
Monovalent anions (e.g., perchlorate, thiocyanate) or{20}
Pyrazolone derivatives, such as phenylbutazone or{07}
Salicylates, chronic administration of or{07}
Salt, iodized, excessive intake of or{07}
Thiopental or{07}
Thyroid blocking agents, such as strong iodine solution, potassium iodide, or potassium perchlorate or{20}
Thyroid preparations, natural or synthetic{20}{30}    (may decrease thyroidal uptake of iodide I 131; it is recommended that these medications or preparations be withheld for the following periods of time prior to administration of sodium iodide I 131: 1 week for corticosteroids; 4 weeks for benzodiazepines; 2 to 4 weeks for intravascular iodinated contrast media and more than 4 weeks for cholecystographic agents; 2 to 4 weeks for iodine-containing preparations, such as vitamins, expectorants, antitussives, and topical medications; 1 or 2 weeks for pyrazolone derivatives; 1 week for thiopental; 4 to 6 weeks for thyroxine; and 2 or 3 weeks for triiodothyronine {02} {07} {20} {22} {51})

    (a rebound effect may occur following the sudden withdrawal of antithyroid preparations, resulting in a period of up to 5 days of very high thyroidal uptake; it is recommended that antithyroid medications be discontinued 3 to 4 days prior to administration of sodium iodide I 131 {07} {20} {47})

    (chronic salicylate administration may cause a depression of thyroid function; salicylate therapy should be discontinued at least 1 to 2 weeks prior to sodium iodide I 131 administration; however, a rebound effect may also occur following discontinuation of salicylate therapy, resulting in a period of 3 to 10 days of increased thyroidal uptake {01} {07})


Bone marrow depressants, other (see Appendix II )    (concurrent use may rarely increase the bone marrow depressant effects of these medications and radiation therapy; dosage reduction of other bone marrow depressant medications may be required)


Medical considerations/Contraindications
The medical considerations/contraindications included have been selected on the basis of their potential clinical significance (reasons given in parentheses where appropriate)— not necessarily inclusive (» = major clinical significance).


Risk-benefit should be considered when the following medical problems exist
Diarrhea or
Vomiting    (radiation exposure and loss of therapeutic dose may result {42} {45} {52})


Low serum chlorides or
Nephrosis    (may increase thyroidal uptake of iodide I 131 {20})


Renal function impairment    (may decrease excretion of radioiodide, resulting in increased radiation exposure {20})


Sensitivity to the radiopharmaceutical preparation{30}
Thyrotoxic cardiac disease, severe, especially in the elderly    (hyperthyroidism may be aggravated by radiation thyroiditis if antithyroid agents and/or beta-adrenergic blocking agents, such as propranolol, are not given prior to and after treatment {03} {12})



Patient monitoring
The following may be especially important in patient monitoring (other tests may be warranted in some patients, depending on condition; » = major clinical significance):

Thyroid hormones, serum    (determinations of serum concentrations are recommended every 2 to 3 months during the first year after treatment of hyperthyroidism, and annually thereafter, since hypothyroidism may occur several years after treatment {42} {59})




Side/Adverse Effects

Note: The incidence of hypothyroidism following the treatment of Graves' disease is approximately 15 to 25% in the first posttreatment year and increases approximately 2 to 3% per year thereafter. The greater the life expectancy of the patient following treatment, the greater the risk of developing hypothyroidism. {03} {04} {06} {07} {59}

The following side/adverse effects have been selected on the basis of their potential clinical significance (possible signs and symptoms in parentheses where appropriate)—not necessarily inclusive:

Those indicating need for medical attention
    
Hypothyroidism (changes in menstrual periods; clumsiness; coldness; drowsiness; dry, puffy skin; headache; listlessness; muscle aches; temporary thinning of hair [may occur 2 to 3 months after treatment]; unusual tiredness or weakness; weight gain)—dose-dependent{01}{07}{31}{32}{46}{51}{56}
Note: Hypothyroidism may occur several years following successful treatment of hyperthyroidism; therefore, annual blood tests for thyroid hormone concentration are recommended. {42} {43}


Incidence rare
Following treatment of hyperthyroidism
    
Exaggerated hyperthyroid state (excessive sweating, fast heartbeat, fever, palpitations, unusual irritability or unusual tiredness)—due to radiation thyroiditis{01}{12}{22}

Following treatment of thyroid carcinoma
    
Leukopenia{45}{52} (cough or hoarseness, fever or chills, lower back or side pain, painful or difficult urination)
    
thrombocytopenia{01}{18}{30}{33}{34}{35}{52} (unusual bleeding or bruising; black, tarry stools; blood in urine or stools; pinpoint red spots on skin)




Those indicating need for medical attention only if they continue or are bothersome
Incidence less frequent
Following treatment of hyperthyroidism or thyroid carcinoma
    
Radiation thyroiditis{03}{12}{30}{31}{33}{45} (neck tenderness or swelling or sore throat)

Following treatment of thyroid carcinoma
    
Temporary loss of taste
    
radiation gastritis{01}{30}{45} (temporary nausea and vomiting)
    
radiation sialadenitis{01}{15}{45} (tenderness of salivary glands)






Patient Consultation
As an aid to patient consultation, refer to Advice for the Patient, Sodium Iodide I 131 (Therapeutic) .

In providing consultation, consider emphasizing the following selected information (» = major clinical significance):

Description of use
Action in the body: Radioiodide uptake by the thyroid and functioning thyroid cancer metastases same as uptake of nonradioactive iodine

Large doses are used therapeutically to damage or destroy thyroidal tissue in management of hyperthyroidism or thyroid carcinoma

Before using this medication
»   Conditions affecting use, especially:

Pregnancy—Radioiodide crosses placenta; risk to fetus from radiation exposure; use contraindicated because of possibility of causing hypothyroidism in newborn {42}





Breast-feeding—Distributed into breast milk; complete cessation of nursing recommended because of risk to infant from radiation exposure; possibility of causing hypothyroidism in newborn





Use in children—Vomiting may present management problems in some children


Proper use of this medication
Special preparatory instructions may apply; patient should inquire in advance

Precautions after using this medication

Following treatment of hyperthyroidism or thyroid carcinoma {03}
To prevent radiation contamination of other persons or environment: For 48 to 96 hours after receiving radioiodide— {35} {37} {41}
» Not kissing anyone and not handling or using another person's eating or drinking utensils, toothbrush, or bathroom glass {22}

» Not engaging in sexual activities

» Avoiding close and prolonged contact with others, especially children and pregnant women {59}

Sleeping alone

» Washing sink and tub after use (including brushing teeth)

» Washing hands after using or cleaning toilet

Using separate towels and washcloths

Laundering clothes and linens separately

» Double-flushing toilet

To decrease radiation exposure to the urinary bladder: Increasing intake of fluids to promote more frequent voiding to help eliminate radioactive iodine {22}

Following treatment of hyperthyroidism
Periodic blood tests to check thyroid hormone concentration {51}


Side/adverse effects
Signs of potential side effects, especially hypothyroidism or hyperthyroid state (following treatment of hyperthyroidism); leukopenia and thrombocytopenia (following treatment of thyroid carcinoma)


General Dosing Information
Radiopharmaceuticals are to be administered only by or under the supervision of physicians who have had extensive training in the safe use and handling of radioactive materials and who are authorized by the Nuclear Regulatory Commission (NRC) or appropriate state agency, or, outside the U.S., the appropriate authority.

Adequate hydration of the patient is recommended before and after administration of radioiodide to assure rapid elimination of the iodide that is not incorporated into the gland. {07}

The radiation dose to the thyroid gland from sodium iodide I 131 is dependent upon the uptake as well as the size of the gland and the amount of radioiodide administered. Thyroidal uptake and size should be determined by the physician prior to treatment and may be useful in calculating the therapeutic dose. {22}

In some cases, patients with thyroid carcinoma may be pre-treated with recombinant human thyrotropin, lithium carbonate, or a low-iodine diet in order to increase uptake and/or retention in neoplastic thyroid tissue {63} {65} {66} {67}.

Safety considerations for handling this medication
Guidelines for the receipt, storage, handling, dispensing, and disposal of radioactive materials are available from scientific, professional, state, federal, and international bodies. Handling of this radiopharmaceutical should be limited to those individuals who are appropriately qualified and authorized. {58}


Safety considerations for patients after treatment
A large fraction of administered activity {63} may be excreted in the urine, with small, but potentially significant fractions excreted in feces, perspiration, saliva, and on the skin of patients treated with radioiodide. This may present a contamination hazard during hospitalization and after discharge. For this reason: {35} {36} {37} {46} {51}

   • Patients need to be instructed at time of discharge in techniques to prevent transfer of radioactivity to family members and the environment after release from the hospital. {35} {36}
   • For most radioiodide thyroid carcinoma therapy patients, close contact with other persons may be resumed 2 to 4 days after release from the hospital; the time period may be longer for hyperthyroid therapy patients since the excretion of radioiodide in these patients is not as rapid as in the thyroid carcinoma patients. {37}


Veterinary Information
Sodium iodide I 131 is not specifically approved for veterinary use; therefore, there is no product labeling identifying approved indications and administered activities.

Sodium iodide I 131 is used for the treatment of hyperthyroidism caused by multinodular adenoma or hyperplasia of the thyroid gland in cats. {11} {27} Also, sodium iodide I 131 is used for the treatment of carcinoma of the thyroid gland in cats and dogs. {41}

In addition to information included in this monograph and consultation with a veterinary radiologist or radiation oncologist, the following information may be helpful for use of sodium iodide I 131 in animals:

   • Licensing is required for the handling and use of radiopharmaceuticals that is specific to a given state {63}. Animals are typically held in a radiation confinement ward until time of release according to federal and state regulations that have been established as acceptable release criteria based on surface exposure rates. Also, unlike human excreta, non-human excreta must be decayed out or sent to a low level radioactive waste site {63}. Iodine I 131-contaminated excreta is generally decayed out for approximately 80 days {63}.
   • Following treatment of hyperthyroidism in cats, serum thyroxine (T 4) concentrations have been reported to decrease most rapidly during the first 3 to 6 days after treatment and to return to normal or near normal within a month. {27} {62} An exaggerated hyperthyroid state or hypothyroidism also has been reported in a smaller percentage of cats following treatment with radioactive iodine. {27} {40} {41} {44} Animals with clinical and clinicopathologic features of hypothyroidism may require supplementation with L-thyroxine. {44}
   • Following treatment of thyroid carcinoma, hypothyroidism is commonly seen, for which L-thyroxine supplementation may be required. {41}
   • A significant decline in the renal function of cats, which may precipitate renal failure, has been reported after treatment of hyperthyroidism with radioactive iodine. {62} It is recommended that pretreatment measurements of glomerular filtration rate be performed to detect subclinical renal disease and to predict which cats may have clinically important declines in renal function after treatment with radioactive iodine. {62} Also, reduction of serum T 4 concentrations after treatment of hyperthyroidism with radioactive iodine may result in azotemia in older cats with chronic renal disease. {61} {62}
   • Although the optimal method of dosimetry remains to be determined, the administered activity is usually calculated on the basis of the severity of clinical signs, peak radioactive iodine uptake, serum T 4 concentration, and/or thyroid gland weight. {11} {44}
   • The activity of radioactive iodine administered in the treatment of benign hyperplasia has ranged as follows (depending on the size of the animal):

• For Sodium Iodide I 131 Capsules USP— Cats: Oral, 200 to 300 megabecquerels (5.4 to 8.1 millicuries). {38}


• For Sodium Iodide I 131 Solution USP— Cats: Intravenous or subcutaneous, 55.5 to 227 megabecquerels (1.5 to 6.13 millicuries). {11} {27} {40} {44}

   • The activity of radioactive iodine administered in the treatment of thyroid carcinoma has ranged as follows (depending on the size of the animal):

• For Sodium Iodide I 131 Solution USP—

Cats: Intravenous or subcutaneous, 1110 to 1480 megabecquerels (30 to 40 millicuries). {41}Dogs: Intravenous or subcutaneous, 1480 to 4440 (40 to 120 millicuries).


   • All sodium iodide I 131 solution products currently marketed in the United States are formulated for oral administration. If intravenous or subcutaneous injection is desired, a sodium iodide I 131 solution product that complies with USP specifications for parenteral use should be individually compounded {63}.
   • Specific instructions should be given to the pet owner explaining posttreatment confinement and waste disposal.



Oral Dosage Forms

SODIUM IODIDE I 131 CAPSULES USP

Usual adult and adolescent administered activity
Disease therapy


Antihyperthyroid agent:
Oral, 148 to 370 megabecquerels (4 to 10 millicuries). {01} {07} {30} {39} {45} {52}

Note: The administered activity is usually individualized based on the estimated weight of the patient's thyroid gland and measurement of the 24-hour radioiodide uptake. {46} {51}
Toxic nodular goiter and other serious thyroid conditions may require larger dosages (e.g., 555 to 1110 megabecquerels [15 to 30 millicuries]). {42} {45} {52}




Antineoplastic:


Ablation of normal thyroid tissue—
Oral, 1.85 gigabecquerels (50 millicuries), with a range of 1.1 to 3.7 gigabecquerels (30 to 100 millicuries). {45} {52}



Subsequent therapy for metastases—
Oral, 3.7 to 7.4 gigabecquerels (100 to 200 millicuries). {01} {22} {42}




Usual pediatric administered activity
Dosage must be individualized by physician.

Usual geriatric administered activity
See Usual adult and adolescent administered activity.

Strength(s) usually available
U.S.—


28 megabecquerels to 3.7 gigabecquerels (0.75 to 100 millicuries) per capsule at time of calibration (Rx)[Generic]{29}


37 megabecquerels to 1.85 gigabecquerels (1 to 50 millicuries) per capsule at time of calibration (Rx) [Iodotope{30}]


37 megabecquerels to 4.81 gigabecquerels (1 to 130 millicuries) per capsule at time of calibration (Rx) [Iodotope{45}]

Canada—


Each gelatin capsule contains an individually dispensed dose of sodium iodide I 131 as prescribed (Rx)[Generic]

Packaging and storage:
Store between 15 and 30 °C (59 and 86 °F), unless otherwise specified by manufacturer. {45} {52} Store in a well-closed container. {54}

Note: Caution—Radioactive material.



SODIUM IODIDE I 131 SOLUTION USP

Usual adult and adolescent administered activity
See Sodium Iodide I 131 Capsules USP.

Usual pediatric administered activity
See Sodium Iodide I 131 Capsules USP.

Usual geriatric administered activity
See Usual adult and adolescent administered activity.

Strength(s) usually available
U.S.—


129.5 megabecquerels to 5.5 gigabecquerels (3.5 to 150 millicuries) per vial at time of calibration (Rx)[Generic](sodium bisulfite 0.1%, edetate disodium 0.2%){28}{53}


259 megabecquerels to 3.93 gigabecquerels (7 to 106 millicuries) per vial at time of calibration (Rx) [Iodotope (edetate disodium 1 mg per mL)]{45}

Canada—


Each vial contains an individually dispensed dose of sodium iodide I 131 as prescribed (Rx)[Generic]

Packaging and storage:
Store between 15 and 30 °C (59 and 86 °F), unless otherwise specified by manufacturer. {45} {53}

Note: Caution—Radioactive material.


Additional information:
Radioiodide stock solutions and any dilutions thereof must be maintained at a pH of 7.5 to 9.0 in order to minimize oxidation of iodide to volatile forms of iodine. Additionally, 0.2% sodium thiosulfate may be incorporated into these solutions if an antioxidant is desired. {01} {42}



Revised: 6/15/1999



References
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