The present invention relates to a method for administering water soluble physiologically active substances, said method comprising intranasally administering to a subject an aqueous composition comprising 0.001-25 wt.% of one or more fully dissolved physiologically active substances, the physiologically active substances having a water solubility in demineralized water of at least 15 mg/mL at 20°C of, 0.01-10 wt.% nicotinamide, and at least 60 wt.% water. The invention also relates to a kit comprising said composition and to the use of nicotinamide as an enhancer of intranasal absorption of a physiologically active substance from an aqueous solution, wherein the aqueous solution further comprises 0.01-10 wt.% nicotinamide.
