The invention relates to a dosing device that comprises a medium reservoir (S) and a pump device for dosing and dispensing a medium stored in said medium reservoir. The pump device is associated with a pump chamber, and with at least one inlet and one outlet valve. According to the invention, the inlet valve is configured as a sliding valve (10, 12) which, in its closed position, can be displaced by a dosing stroke that defines a dosing volume for the pump chamber (17). The invention further relates to the use of said dosing device for dispensing pharmaceutical active substances, especially for nasal administration.