An adapter for a dispensing container in a planetary mixer and an adapter and dispensing container combination are provided. The container has a longitudinal axis and a transverse axis and includes a composition dispensing nozzle with a removable cap closing the dispensing nozzle, the removable cap having a first width dimension measured along the transverse axis, and a container part spaced apart from the dispensing nozzle along the longitudinal axis, the container part having a second width dimension measured along the transverse axis. The adapter includes a cavity for receiving the cap, the cavity having a transverse dimension that exceeds the first width dimension, and a passageway extending from the cavity for receiving the container therein, the passageway having a transverse dimension that is less than the first width dimension and less than the second width dimension.