AÂ method of reducing the respiratory depressant effect associated with diamorphine (diacetylmorphine, morphine diacetate or heroin) administration, wherein the method comprises administering intranasally a single dose pharmaceutical composition comprising (a) lyophilised diamorphine or a pharmaceutically acceptable salt thereof and (b) a diluent for reconstitution comprising a preservative, a chelating agent, one or more osmolarity modifiers and a pH modifier. Preferably the osmolarity modifiers are selected from the group including sodium chloride, potassium chloride, glycerol (glycerine), trehalose, mannitol, sorbitol, dextrose, lactose and arginine. The preservatives may be selected from m-cresol, phenol, alcohol, benzyl alcohol, methyl-, ethyl-, propyl- and butyl-paraben, thiomersal, chlorobutanol, benalkonium chloride or combination thereof. Preferably the chelating agent is edetic acid and its salts, including sodium edentate or disodium dentate. The pH modifier may be selected from sodium hydroxide, hydrochloric acid and buffers such as phosphate, acetate, carbonate, citrate, glutamate and prolamine. The formulation is useful in the treatment of pain. A kit for the preparation of a multi-dose pharmaceutical composition of a nasal analgesic in the form of a nasal spray comprising a bottle containing a lyophilised nasal analgesic, a tube containing a diluent for reconstitution, modified nasal pump, one or more disposable nasal tips and instructions for assembly is also outlined.
