US Patent 9597454 Syringes for prefilled and fill-at-use mixing and drug delivery

Mixing syringes including a valve mechanism are configured and configurable to enable one or more substances to be prefilled into the syringe. The valve mechanism may be an aspect of a distal seal assembly. Actuation of the valve mechanism permits opening of a fluid passage for the mixing of one or more substances, and the resulting mixed substance can be delivered by the syringe, for example, for administration of a pharmaceutical to a subject.