Potassium Iodide (potassium iodide)

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Potassium iodide is administered orally.

For use during a radiation emergency, potassium iodide is commercially available as tablets containing 65 or 130 mg of the drug and as an oral solution containing 65 mg/mL. If the oral solution containing 65 mg/mL is used, the dose should be administered undiluted using the calibrated dropper provided by the manufacturer.

For other indications, an oral solution of potassium iodide containing 1 g/mL (also known as saturated solution of potassium iodide (SSKI(R))) also is available. If this oral solution is used, the dose should be administered in a glassful of water, fruit juice, or milk. To minimize GI irritation, the dose should be taken with food or milk. A calibrated dropper marked to deliver 300 mg (0.3 mL) or 600 mg (0.6 mL) of the drug is provided by the manufacturer. If a dose of the oral solution containing 1 g/mL is administered using a standard medicinal dropper, each drop (0.05 mL) contains 50 mg of potassium iodide.

Potassium iodide may be available as strong iodine solution (also known as Lugol's solution), an oral solution containing 50 mg of iodine and 100 mg of potassium iodide per mL; this preparation may be commercially available but is not approved by the US Food and Drug Administration (FDA). Doses of strong iodine solution should be diluted in water or juice. If a dose of strong iodine solution is administered using a standard medicinal dropper, each drop contains 8 mg of iodide.

Concomitant use of lithium salts and iodides may result in additive or synergistic hypothyroid effects. Hypothyroidism has been reported in several patients who received the drugs concomitantly. A lithium salt and potassium iodide generally should not be used concomitantly; if the drugs are used together, the patient should be monitored closely for signs and symptoms of hypothyroidism.

Concomitant use of antithyroid agents (e.g., methimazole) and potassium iodide may result in additive hypothyroid and goitrogenic effects.

Concomitant use of potassium iodide and potassium-containing drugs, potassium-sparing diuretics, or angiotensin-converting enzyme (ACE) inhibitors may be associated with hyperkalemia, which may result in cardiac arrhythmias or cardiac arrest.

There are no contraindication interactions for this drug.

Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

Agents That Affect Iodide/Radioactive Iodide

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Many compounds can affect iodide protein binding and alter iodide pharmacokinetics and pharmacodynamics.(1)

CLINICAL EFFECTS: Compounds that affect iodide pharmacokinetics and pharmacodynamics may impact the effectiveness of radioactive iodide.(1)

PREDISPOSING FACTORS: Compounds that affect iodide pharmacokinetics and pharmacodynamics are expected to have the most impact during therapy using radioactive iodide. Diagnostic procedures would be expected to be impacted less.

PATIENT MANAGEMENT: Discuss the use of agents that affect iodide pharmacokinetics and pharmacodynamics with the patient's oncologist.(1) Because indocyanine green contains sodium iodide, the iodine-binding capacity of thyroid tissue may be reduced for at least one week following administration. Do not perform radioactive iodine uptake studies for at least one week following administration of indocyanine green.(2) The manufacturer of iopamidol states administration may interfere with thyroid uptake of radioactive iodine and decrease therapeutic and diagnostic efficacy. Avoid thyroid therapy or testing for up to 6 weeks post administration of iopamidol.(3)

DISCUSSION: Many agents interact with radioactive iodine. The average duration of effect is: anticoagulants - 1 week antihistamines - 1 week anti-thyroid drugs, e.g: carbimazole, methimazole, propylthiouracil - 3-5 days corticosteroids - 1 week iodide-containing medications, e.g: amiodarone - 1-6 months expectorants - 2 weeks Lugol solution - 3 weeks saturated solution of potassium iodine - 3 weeks vitamins - 10-14 days iodide-containing X-ray contrast agents - up to 1 year lithium - 4 weeks phenylbutazone - 1-2 weeks sulfonamides - 1 week thyroid hormones (natural or synthetic), e.g.: thyroxine - 4 weeks tri-iodothyronine - 2 weeks tolbutamide - 1 week topical iodide - 1-9 months (1)

Agents That Affect Iodide/Sodium Iodide I 131

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Many compounds can affect iodide protein binding and alter iodide pharmacokinetics and pharmacodynamics.(1,2)

CLINICAL EFFECTS: Compounds that affect iodide pharmacokinetics and pharmacodynamics may impact the effectiveness of radioactive iodide.(1,2)

PREDISPOSING FACTORS: Compounds that affect iodide pharmacokinetics and pharmacodynamics are expected to have the most impact during therapy using radioactive iodide. Diagnostic procedures would be expected to be impacted less.

PATIENT MANAGEMENT: Discuss the use of agents that affect iodide pharmacokinetics and pharmacodynamics with the patient's oncologist.(1,2) Because indocyanine green contains sodium iodide, the iodine-binding capacity of thyroid tissue may be reduced for at least one week following administration. Do not perform radioactive iodine uptake studies for at least one week following administration of indocyanine green.(3) The manufacturer of iopamidol states administration may interfere with thyroid uptake of radioactive iodine and decrease therapeutic and diagnostic efficacy. Avoid thyroid therapy or testing for up to 6 weeks post administration of iopamidol.(4)

DISCUSSION: Many agents interact with radioactive iodine. The average duration of effect is: anticoagulants - 1 week antihistamines - 1 week anti-thyroid drugs, e.g: carbimazole, methimazole, propylthiouracil - 3-5 days corticosteroids - 1 week iodide-containing medications, e.g: amiodarone - 1-6 months expectorants - 2 weeks Lugol solution - 3 weeks saturated solution of potassium iodine - 3 weeks vitamins - 10-14 days iodide-containing X-ray contrast agents - up to 1 year lithium - 4 weeks phenylbutazone - 1-2 weeks sulfonamides - 1 week thyroid hormones (natural or synthetic), e.g.: thyroxine - 4 weeks tri-iodothyronine - 2 weeks tolbutamide - 1 week topical iodide - 1-9 months (1,2)

Moderate Interaction: Assess the risk to the patient and take action as needed.

Iodide Salts/Lithium

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Unknown.

CLINICAL EFFECTS: Concurrent administration of lithium and iodide salts may produce hypothyroidism.

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: If both drugs are given, monitor patient for signs and symptoms of hypothyroidism. If hypothyroidism develops, thyroid hormone may be used to treat symptoms.

DISCUSSION: Hypothyroidism is a side effect that may occur with long-term lithium treatment. Thyroid gland enlargement and increased thyroid stimulating hormone may also be present. Iodide administration to patients receiving lithium may increase the risk of patients developing hypothyroidism.

Selected Minerals, Oral/Trientine

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Mineral supplements may bind to trientine and block its absorption.

CLINICAL EFFECTS: The levels and clinical effects of trientine may be decreased.

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The US manufacturer of trientine states that mineral supplements should not be given with trientine. If concomitant therapy is necessary, take trientine on an empty stomach and separate administration at least one hour apart from any other drug. Monitor clinical status for decreased effectiveness and adjust the trientine dose if necessary.

DISCUSSION: Multivitamins with minerals may decrease trientine absorption so ensure patient is aware of the risks and counsel on instructions for concurrent use.

There is no enhanced messaging for this drug.

• Dermatitis herpetiformis
• Pregnancy

• Active tuberculosis
• Hyperkalemia
• Hypocomplementemic urticarial vasculitis
• Kidney disease with reduction in glomerular filtration rate (GFr)

• Goiter
• Hashimoto thyroiditis

There is no enhanced messaging for this drug.

Less Frequent

• Angioedema
• Arthralgia
• Eosinophilia
• Lymphadenopathy
• Urticaria

Rare or Very Rare

• Iodine poisoning
• Polyarteritis nodosa
• Systemic lupus erythematosus
• Thrombotic thrombocytopenic purpura

Less Frequent

• Dysgeusia
• Nausea

Rare or Very Rare

• Diarrhea

No enhanced messaging available.

No enhanced messaging available.

Iodides readily cross the placenta and may result in abnormal thyroid function and/or goiter in the neonate. Fetal thyroid may be most susceptible to the effects of excess iodine at the end of gestation.

Some experts state that potassium iodide is contraindicated in pregnant women. The American Academy of Pediatrics (AAP) states that use of potassium iodide as an expectorant is contraindicated during pregnancy.

There is no evidence that short-term use (e.g., 10 days) of potassium iodide for preoperative management of hyperthyroidism in pregnant women with Graves' disease undergoing thyroidectomy+ is harmful to the fetus. If thyroidectomy is necessary for the treatment of hyperthyroidism during pregnancy, the American Thyroid Association (ATA) and American Association of Clinical Endocrinologists (AACE) recommend that the surgery be performed during the second trimester.

The FDA recommends that pregnant women receive potassium iodide during a radiation emergency for their own protection and that of the fetus; however, repeat administration should be avoided during pregnancy, unless other protective measures are not available. When repeat administration is indicated in a pregnant woman, consultation with a clinician is recommended and thyroid function monitoring may be indicated in the neonate.

If potassium iodide is used during pregnancy or if the patient becomes pregnant while receiving the drug, the patient should be informed of the potential risks to the fetus.

Potassium iodide is distributed into milk and may cause rash and thyroid suppression in nursing infants.

The AAP considers potassium iodide to be compatible with breast-feeding.

In a radiation emergency, the FDA recommends that lactating women receive potassium iodide for their own protection. However, repeat administration should be avoided in lactating women unless other protective measures are not available. If repeat administration is indicated in a nursing woman, consultation with a clinician is recommended; thyroid function monitoring may be indicated in a breast-fed neonate.

Because radioactive iodine is distributed into milk, some experts (including the AAP) recommend that lactating women temporarily not breast-feed after a radiation emergency, unless no alternative is available. Breast-feeding can then be resumed when public authorities declare it safe to do so. The fact that administration of potassium iodide to lactating women potentially can reduce the radioiodine content of milk should be considered.

No enhanced messaging available.