Narasin sodium is prepared from narasin taking advantage of the carboxylic acid which ionises and readily forms the salt in sodium hydroxide solutions. Narasin is an ionophore with broad spectrum activity against Gram positive bacteria including anaerobes and mycoplasma, and also possesses antiviral and limited antifungal activity. Narasin is used in the animal health industry as an in-feed antibiotic and growth promotant.