Chlorhexidine-cyclodextrin formulation for Acanthamoeba keratitis

GERPAC Congress highlights

Cyclodextrin-based chlorhexidine eye drops represent a promising approach to formulating stable and effective treatments for Acanthamoeba keratitis, according to researchers from the University of Picardy Jules Verne.

Acanthamoeba keratitis is a rare but serious, sight-threatening corneal infection caused by the acanthamoeba parasite. Chlorhexidine has demonstrated efficacy against acanthamoeba but no eye-drop formulation was available. Moreover, the use of chlorhexidine digluconate (CD), the most soluble form, was limited due to precipitation (of chlorhexidine hydrochloride) in the presence of chloride ions in vivo. In 2024 Akantior® eyedrops (polyhexanide 0.08%) were approved for this indication. Akantior was designated as an orphan medicine. Professor Frédéric Marçon noted that Akantior costs about €8,754 for 30 vials of 0.3 ml. The present study screened a number of cyclodextrins for their ability to form inclusion complexes with CD that would effectively protect the chlorhexidine from precipitation in saline conditions. Two suitable products were found and further investigations showed that they could be formulated as eyedrops and that the antibacterial activity of the chlorhexidine was preserved in vitro.

In vitro conditions may not reflect conditions in the eye and this could influence the efficacy of the formulation. Professor Marçon said that another important consideration was that acanthamoeba parasites tend to encyst in the cornea.

Professor Irene Kraemer said that at the University Hospital of Mainz they prepare polyhexanide eyedrops for this indication in a different strength from the commercial product.

Sebastian Rigaud et al. Formulation of a Cyclodextrin-Based Ophthalmic Drug Solution of Chlorhexidine for the treatment of Acanthamoeba Keratitis. Short communication. GERPAC Congress 2025

Photo: Frédéric Marçon. Photo – courtesy of GERPAC