A medicament powder, system and method for nasal administration of a pharmacologically active peptide across the nasal mucous membrane. A free-flowing powder having a low moisture content includes a cross-linked cation exchange resin in anionic form and a pharmacologically active peptide in cationic form ionically bound together. The particles of the powder function as carriers of the peptide during nasal administration. The cation exchange resin is taken from the group consisting of divinyl benzene cross-linked polystyrene-sulfonates and Na, NH.sub.4 and K salts thereof. An N-saline solution is sprayed into the nasal cavity after administration of the powder to effect ion exchange of Na in the N-saline with the peptide from the resin for efficient delivery of the peptide.