A vial adaptor (1010) may comprise a body portion (1020). The body portion includes a vial connection port (1022), a syringe connection port (1024), an access passageway (1026) between the vial connection port and the syringe connection port, and a regulation passageway (1028). The vial adaptor may further comprise an expandable and/or contractible chamber (1040) impermeable to gas and/or liquid, the regulation passageway being between the vial connection port and the chamber, and an expandable housing (1050) casing the chamber. Such a vial adaptor constitutes an improved vial adaptor.
