A spacer device for the oral administration of a volatile medium containing a medicament comprises a chamber ( 110 ) having an inlet ( 102 ) to admit a measured dose of medicament and an outlet ( 104 ) to be received in the mouth, wherein the spacer comprises a butterfly valve ( 106 ). Preferably, the chamber comprises two frustoconical members assembled together coaxially at their divergent ends, said inlet and outlet being respectively at the opposed convergent ends.
