Hexamidine

Abstract: The first medical cure of Acanthamoeba keratitis was obtained by use of propamidine isethionate. Since then, it has been the basic drug recommended for use in treatment. Because some Acanthamoeba strains have been reported to be resistant to propamidine and propamidine was found to be only weakly cysticidal, superior homologs such as butamidine, pentamidine, hexamidine, heptamidine, octamidine, and nonamidine were tested for their amoebicidal effects on two Acanthamoeba strains isolated from patients with keratitis. Trophozoicidal and cysticidal efficiencies were found to be increased from propamidine to nonamidine; i.e., when the alkyl chain connecting the two benzene rings in their molecular structures was elongated, in comparison with propamidine, hexamidine and octamidine were the most amoebicidal molecules. As a result of these data, a kinetic study carried out on propamidine, hexamidine, and octamidine demonstrated that the amoebicidal effects resulted from two events: the diffusion of molecules through the plasma membrane or the double wall of trophozoites or cysts, respectively, and the lethal effects of molecules on amoebic protoplasm. The diffusion kinetics were increased when the alkyl chain was elongated, i.e., with an increase in the lipophilic properties of molecules. In contrast, the lethal effect kinetics were found to be unchanged by this elongation, indicating that they originated from the cationic surface-active properties induced by the protonated amidine groups attached to each benzene ring, which themselves remained unchanged from one molecule to the other. These results strongly advocate the immediate replacement of propamidine by hexamidine in the medical treatment of Acanthamoeba keratitis; in France, 0.1% hexamidine eyedrops are available (Desomedine). The results also advocate clinical investigations on the efficiency and toxicity of octamidine, which appears to be the most amoebicidal diamidine in vitro.

Abstract: Compositions useful for regulating the condition of mammalian keratinous tissue needing such treatments are provided. An exemplary composition comprises a safe and effective amount of glycyrrhizic acid and/or glycyrrhetinic acid; a safe and effective amount of an active selected from the group consisting of N-acyl amino acid compounds, hexamidine, cetyl pyridinium chloride, ergothioneine, and combinations thereof; and a dermatologically acceptable carrier.

Abstract: Skin care compositions and methods for regulating the condition of mammalian keratinous tissue containg an effective amount of a dialkanoyl hydroxyproline compound and a second skin care compound selected from hexamidine compounds, sugar amine compounds and their combination. These compositions may be either an emulsion or a solution wherin the dialkanoyl hydroxyproline compound may be converted to its salt for incorporation into the aqueous phase of a compositions.