Potassium Iodide

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Cat Number

CHE7681110

CAS Number

7681-11-0

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Product Detail Description Scientific Support Customer Q&A

CAS Number

7681-11-0

EINECS

231-659-4

Storage

Store at room temperature

Synonyms

Kali iodide; Thyroshield; Knollide

Molecular Formula

Molecular Weight

166

Smiles

[K+].[I-]

Appearance

White crystalline solid

Melting Point

681℃

Boiling Point

1330-1420℃

Relative Density

3.123

General Description

Potassium iodide is an inorganic salt that serves as a source of stable iodide for thyroid protection and as an expectorant. The compound has a salty, bitter taste and is rapidly absorbed from the gastrointestinal tract.

Mechanism of Action

In the setting of radiation exposure, stable iodide saturates the thyroid gland, preventing the uptake of radioactive iodine isotopes by the sodium-iodide symporter. This competitive inhibition reduces the risk of thyroid cancer. As an expectorant, potassium iodide increases respiratory tract fluid production, thinning mucus and facilitating cough. The drug also suppresses thyroid hormone synthesis and release during thyrotoxic crisis.

Application

Potassium iodide is FDA-approved for thyroid blocking during nuclear radiation emergencies, protecting the gland from radioactive iodine uptake. It is also used in the preoperative preparation of hyperthyroid patients for thyroidectomy and for the treatment of thyrotoxic crisis.

Rose bengal (RB), a xanthene dye, mediates photodynamic inactivation of Gram‑positive bacteria but is largely ineffective against Gram‑negative species. Adding nontoxic potassium iodide (100 mM) potentiated green light‑mediated killing of E. coli, P. aeruginosa, MRSA, and Candida albicans by up to 6 extra logs. The mechanism involves singlet oxygen reacting with iodide to form peroxyiodide, which decomposes into radicals, hydrogen peroxide, and molecular iodine. KI also potentiated RB photodynamic therapy in a mouse model of P. aeruginosa‑infected skin abrasions, suggesting a simple, broad‑spectrum enhancement strategy.

Fig. 1 Monitoring of aPDT of skin abrasions infected with P. aeruginosa in the days following light delivery. (Wen X, et al., 2017)

References

Wen X, et al. Potassium Iodide Potentiates Antimicrobial Photodynamic Inactivation Mediated by Rose Bengal in In Vitro and In Vivo Studies. Antimicrob Agents Chemother. 2017;61(7):e00467-17.

Does Potassium Iodide require protection from light and oxygen during storage?

Yes, it is sensitive to light and air. Exposure can cause oxidation to iodine (I₂), leading to discoloration (yellow/brown). Store in light-resistant, airtight containers.

What is the recommended storage temperature for Potassium Iodide?

Store at controlled room temperature (15-25°C). Avoid excessive heat and humidity, which accelerate oxidation and caking.

Is Potassium Iodide stable in solution for expectorant or thyroid blocking formulations?

Aqueous solutions are stable when protected from light and air, but antioxidants (e.g., sodium thiosulfate) are often added to prevent iodine formation.

How is the free iodine content monitored during stability?

Free iodine is quantified using a validated titrimetric or colorimetric method, ensuring it remains below pharmacopoeial limits (typically ≤ 0.1%).