Injection device having polyparaxylylene coated container

Claim 1

An automatic injector comprising: a housing; a metallic cartridge contained within said housing, said cartridge having at least an inner surface thereof coated with polyparaxylylene to reduce the coefficient of friction of said inner surface; a charge of medicament contained in said metallic cartridge and in communication with said polyparaxylylene coating, said polyparaxylylene coating preventing ions from being extracted from said metallic cartridge into said medicament; a plunger normally disposed in a generally rearward end of said metallic cartridge and movable through said metallic cartridge toward a generally forward end thereof in response to a predetermined actuating procedure, said movable plunger rearwardly confining said medicament within said metallic cartridge and being in slidable sealed relation with said polyparaxylylene coating provided on said metallic cartridge, said polyparaxylylene coating sufficiently reducing the coefficient of friction of said inner surface to reduce the time required for said plunger to travel from said generally rearward end to said generally forward end of said metallic cartridge; a needle normally disposed within said housing, said needle being projectable from a forward end of said housing and communicable with said medicament so that movement of said plunger through said cartridge forces said medicament through said needle and into the flesh of an individual in response to said predetermined actuating procedure; and a releasable energy source releasable in response to said predetermined actuating procedure to project said needle from the forward end of the housing and slidingly drive said plunger through said metallic cartridge in sealed relation to expel said medicament through said needle and into the flesh of an individual.