Syringe and method for lyophilizing and reconstituting injectable medication

A 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 having an inside surface, 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 and an outer surface, at least said distal end of said plunger stopper being disposed in said chamber, at least one vapor passage defined between the inside surface of said chamber wall and said outer surface of said plunger stopper, said vapor passage extending from said distal end of the plunger stopper and terminating at a location between said ends of said stopper, said proximal end of said 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 a first lyophilization operation of said injectable medication introduced into the syringe barrel, 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 a second reconstitution operation of said lyophilized medication into an injectable form;
• and
• mounting means defined at said proximal end of said plunger stopper for engaging a plunger rod.