IOSAT
Clinical safety rating: caution
Comprehensive clinical and safety monograph for IOSAT (IOSAT).
Blocks thyroidal uptake of radioactive iodine isotopes, reduces thyroid exposure to radiation by saturating thyroid gland with stable iodine.
| Metabolism | Not metabolized; excreted primarily renally as iodide. |
| Excretion | Renal: >99% as iodide; fecal/biliary: <1% |
| Half-life | 3-5 days in euthyroid individuals; prolonged in hyperthyroidism (6-12 days) and renal impairment (up to 30 days) |
| Protein binding | Minimal (<1%); primarily free iodide |
| Volume of Distribution | 0.2-0.3 L/kg (extracellular fluid space) |
| Bioavailability | Oral: >90% |
| Onset of Action | Oral: 24-48 hours for thyroid blockade; IV: immediate |
| Duration of Action | Oral: up to 2 weeks after single dose; protective effect maintained with continued daily dosing |
Adults: 130 mg orally once daily for potassium iodide (SSKI 1 g/mL). For thyroid protection in radiation exposure: 130 mg orally once, may repeat after 24 hours if necessary.
| Dosage form | TABLET |
| Renal impairment | No specific dosage adjustment required for renal impairment; however, monitor serum potassium in patients with chronic kidney disease due to potential hyperkalemia. |
| Liver impairment | No dosage adjustment necessary for hepatic impairment. |
| Pediatric use | Infants (<1 month): 16 mg orally once daily. Children 1 month to 3 years: 32 mg orally once daily. Children 3-12 years: 65 mg orally once daily. Adolescents 12-18 years: 130 mg orally once daily. |
| Geriatric use | No specific dosage adjustment required; use with caution in elderly due to higher risk of hyperkalemia and electrolyte disturbances. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for IOSAT (IOSAT).
| Breastfeeding | Potassium iodide (KI) is excreted into breast milk; M/P ratio approximately 1.0. Concentrations in milk may exceed maternal plasma. Breastfeeding should be interrupted for 24-48 hours after maternal dose to reduce infant iodide exposure. If continued, monitor infant thyroid function. |
| Teratogenic Risk | FDA Pregnancy Category D. First trimester: Iodide crosses placenta; fetal goiter and hypothyroidism may occur from 10 weeks gestation onward due to fetal thyroid iodide trapping. Second and third trimesters: Risk of fetal goiter, tracheal compression, and neonatal hypothyroidism. Use only for radiation emergency; contraindicated in pregnancy unless radiation exposure risk outweighs fetal thyroid blockade benefit. |
■ FDA Black Box Warning
None
| Serious Effects |
["Hypersensitivity to iodine","Dermatitis herpetiformis","Hypocomplementemic vasculitis","Iodide goiter or thyroid adenoma"]
| Precautions | ["Use in neonates, pregnant or lactating women: risk of thyroid suppression or goiter","Monitor thyroid function with prolonged use","Allergic reactions possible (e.g., angioedema, urticaria)","May interfere with thyroid function tests"] |
| Food/Dietary | No known food interactions. Avoid concurrent use with other iodine supplements. |
| Clinical Pearls |
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| Fetal Monitoring | Maternal: Thyroid function tests (TSH, free T4) before and after administration; monitor for hypersensitivity, salivary gland swelling, metallic taste. Fetal/neonatal: Ultrasound for fetal goiter if used in second/third trimester; neonatal TSH and free T4 screening at birth. |
| Fertility Effects | No direct adverse effects on fertility reported in humans. High-dose iodine may transiently suppress maternal thyroid function but does not impair gametogenesis. |
| IOSAT (potassium iodide) is used for thyroid protection during nuclear radiation emergencies. Administer within 4 hours of exposure for optimal blockade of radioactive iodine uptake. Contraindicated in patients with multinodular goiter, Graves disease, or autoimmune thyroiditis, as it may exacerbate thyrotoxicosis. Monitor for hypothyroidism in neonates and pregnant women. Single-dose efficacy lasts approximately 24 hours; repeat dosing should follow public health guidance. |
| Patient Advice | Take IOSAT only when directed by public health officials during a nuclear emergency. · Swallow tablet whole with water; may crush for children or adults with swallowing difficulties. · Do not take more than directed — overdose can cause thyroid dysfunction. · Common side effects include metallic taste, GI upset, and skin rash; seek medical help for angioedema or difficulty breathing. · Pregnant or breastfeeding women must take as directed to protect infant thyroid. |