Pierceable pharmaceutical container closure with check valve

A pharmaceutical container of the pierceable diaphragm type for storing medication in fluid form for withdrawal when required, said container comprising:

• a housing having a wall structure with an opening and a bottom, said wall structure and said bottom together defining an inner volume;
• a diaphragm sealingly positioned in said opening, said diaphragm having an outer surface and at least one fluid check valve affording one way fluid communication from an ambient atmosphere toward said inner volume when said inner volume has a fluid pressure less than the fluid pressure of the ambient atmosphere, the outer surface having a needle-pierceable, self-healing region;
• a protective cover covering said check valve, the cover including an open needle access region aligned with at least a portion of the needle-pierceable region to leave said needle-pierceable region exposed to the ambient atmosphere;
• a spacer member positioned between said cover and said diaphragm;
• a fluid pathway, defined by the spacer member and the outer surface of the diaphragm, fluidly coupling the needle-pierceable region and said check valve;
• a seal removably positioned on said cover for covering the needle access region to prevent ambient atmosphere flow through the needle access region and the fluid pathway and to said check valve when said seal is installed.