Hexamidine diisethionate (HEX D) is a water-soluble cationic agent with antimicrobial activity against bacteria, fungi, yeasts, and free-living amoebas. This positively charged molecule has a high affinity for the negatively charged cell walls and membranes of bacteria, leading to target cell destruction by disrupting the binding sites. On the other hand, hexamidine diisethionate has low toxicity to human tissues and cells. Therefore, HEX D has been used in the personal care industry and in some over-the-counter (OTC) drug products.

Ophthalmic preparations containing 0.1% hexamidine diisethionate are used to treat minor eye infections such as conjunctivitis and blepharitis. 0.1% benzyl hexamidine diisothionate is also used to treat Acanthamoeba keratitis. However, it is not recommended as a monotherapy for this vision-threatening disease because Acanthamoeba cysts may develop resistance to the drug at the start of treatment or during treatment.

In addition, studies have demonstrated that an ophthalmic solution containing 0.05% hexamidine diisethionate (Keratosept) exhibits in vitro antimicrobial activity against Staphylococcus epidermidis, Staphylococcus aureus, and Candida species. This suggests that it may be a potential candidate for the treatment of staphylococcal and candidal infections of the ocular surface and may play a role in antimicrobial prophylaxis prior to intravitreal injections.

References:

[1] ANTONIO PINNA. In Vitro Antimicrobial Activity of a New Ophthalmic Solution Containing Hexamidine Diisethionate 0.05% (Keratosept).[J]. Accounts of Chemical Research, 2020: 1415-1418. DOI:10.1097/ICO.0000000000002375.

[2] F AVOGARO. Intravitreal injections primary prevention: a case-control study.[J]. European review for medical and pharmacological sciences, 2023, 27 8: 3664-3669. DOI:10.26355/eurrev\_202304\_32153.