Syringe and method for lyophilizing and reconstituting injectable medication

Claim 1

A syringe assembly for lyophilizing and subsequently reconstituting an injectable medication, said syringe assembly comprising: a syringe barrel having an open proximal end, a distal end and a substantially cylindrical chamber wall extending therebetween to define a fluid receiving chamber, a passage extending through said distal end and communicating with said chamber; means for releasably sealing said passage to isolate said chamber from the environment; a plunger stopper having opposed proximal and distal ends, at least said distal end of said plunger stopper being disposed in said chamber, at least one vapor passage defined in said plunger stopper and extending from said distal end thereof terminating at a location between said ends of said stopper, said proximal end of said plunger stopper being dimensioned for sliding fluid-tight sealing engagement with said cylindrical chamber wall so that said distal end of said plunger stopper can be engaged in said chamber with said vapor passage enabling escape of vapor from said chamber during lyophilization of said injectable medication, and said proximal end being dimensioned so that said proximal end of said plunger stopper can be urged into sliding fluid-tight engagement with said cylindrical wall of said chamber upon completion of said lyophilization for sealing the lyophilized medication in said chamber, and said plunger stopper subsequently can be urged proximally for reconstituting said lyophilized medication into an injectable form; and mounting means defined at said proximal end of said plunger stopper for engaging a plunger rod.