Syringe assembly

An insulin syringe with an exchangeable injection needle and an insulin ampulla replaceably connected to said needle and received within a syringe casing, said needle comprising:

• two substantially coaxial needle portions, disposed apart from each other, and separated from each other by a flexible foil-type membrane made of a self-sealing elastomeric material and provided with passage stopping means in line with said two coaxial needle portions, an outer injection needle portion being fastened within a needle receiving body of a needle casing, and an inner needle portion for connection to said insulin ampulla, fastened to a guide body positioned within said needle casing, said passage stopping means being formed as one of a tiny slit and a hole, allowing fluid to flow from said insulin ampulla through said inner needle portion to said outer needle portion, when said fluid is pressure actuated, and in absence of pressure said passage stopping means prevents any fluid flow to said outer needle portion,
• said guide body being inserted into said needle casing by said inner needle portion, and said needle casing having threads, on a cylindrical inner wall, which engage outer threads formed on a neck of said syringe casing so that screwing said syringe casing with said insulin ampulla onto said needle casing causes a tip of said inner needle portion to pierce said insulin ampulla closure and pass insulin to a tip of aid outer needle portion.