Various systems and methods for the pressure-regulated transfer of medical fluids are disclosed. The system can include an adapter assembly that connects with a medical container and with a syringe assembly. The syringe assembly can include a first reservoir and a second reservoir. In various embodiments, when the adapter assembly and the syringe assembly are coupled, the first reservoir and the container can exchange regulating fluid and the second reservoir and the container can exchange medical liquid from the medical container.
