Abstract: A plastic adaptor top for adapting to a chosen syringe a standard cartridge of the kind having a neck with a flange and being closed by a rubber membrane sealingly secured against the flange by a metal cover having its edge beaded behind the flange. This plastic top has a bore for receiving the neck part of the cartridge, which bore has a diameter making it fit over the metal cover and is provided with protrusions gripping behind the edge of the metal cover when the neck part is inserted in the bore. The outer contour of the adaptor top is provided with threads coaxial with the bore to receive a needle hub in a way causing the needle to penetrate the membrane of the cartridge when the hub is mounted on the thread of the plastic top.

Abstract: An insulin injection system comprises a pen shaped syringe with a cartridge containing insulin, and an injection needle. The needle is a G30 needle and the insulin is a type which may freely flow through a G 30 needle. When the insulin is the type comprising suspended crystals the maximal dimension of any crystal is 15 .mu.m.

Abstract: A plastic top for adapting to a chosen syringe (14) a standard cartridge (8) of the kind having a neck (9) with a flange (10) and being closed by a rubber membrane (11) sealingly secured against the flange (10) by a metal cover (12) having its edge beaded behind the flange. This plastic top has a bore (2) for receiving the neck part (9) of the cartridge (8), which bore (2) has a diameter making it fit over the metal cover (12) and is provided with protrusions (3;9) gripping behind the edge of the metal cover (12) when the neck part (9) is inserted in the bore. The outer contour of the plastic top is adapted to the syringe type in which the cartridge is going to be used.The plastic top is provided with a thread (5;18) coaxial with the bore to receive a needle hub (13) in a way making its needle (15) penetrate the membrane (11) of the cartridge (8) when the hub (13) is mounted on the thread (5) of the plastic top.