This physiologically acceptable medium may comprise an aqueous phase and optionally a physiologically acceptable organic solvent chosen, for example, from lower alcohols comprising from 1 to 8 carbon atoms and in particular from 1 to 6 carbon atoms, such as ethanol, isopropanol, propanol or butanol; polyethylene glycols having from 6 to 80 ethylene oxide units; or polyols, such as propylene glycol