A formulation and method for delivery of bioactive substances when applied to, or within, the skin or other exterior region of a mammal. for example, a patient, includes a vasoactive agent; an osmolyte; and an active ingredient. The formulation is sufficiently hygroscopic so as to create a condition of hypertonicity when absorbed by the skin. When the formulation is applied to the skin, the vasoactive agent can be delivered to the dermis so as to contact the vasculature of a patient.