Further Observations on the Biological Properties of Dequalinium (Dequadin) and Hedaquinium (Teoquel)

Abstract

Abstract The activity of dequalinium and hedaquinium against Staphylococcus aureus and Candida albicans is strongly antagonised by the sodium salts of fatty acids, but not by a number of detergents and a commercial liquid soap. Sufficient antagonism was shown by agar to render invalid the results obtained in assays of these antimicrobial agents by the agar plate method. Human saliva had only a slight antagonistic action on both substances. Twenty-one strains of Candida albicans showed some variation in sensitivity towards hedaquinium and dequalinium but none was particularly resistant. Both antimicrobial agents inhibited the growth of Pityrosporum ovale and Trichomonas vaginalis. Both compounds were adsorbed by human or bovine hair on which some remained after repeated washing with water. In cats dequalinium and hedaquinium blocked neuromuscular and ganglionic transmission when injected intravenously in amounts many times greater than the effective dose of suxamethonium chloride. When administered intravenously to mice, hedaquinium in relatively high doses exerted a brief paralysing action.