A medicated module attachable to a drug delivery device. The medicated module comprises a housing configured for attachment to a drug delivery device. The drug delivery device comprises a first medicament. A collapsible reservoir is contained within the housing. A pre-determined volume of a second medicament is contained within the reservoir. A needle arrangement is configured within the housing and the needle arrangement is arranged in fluid communication with the collapsible reservoir. A needle shroud may be configured, such that, during an injection step, the shroud acts on the reservoir to inject the second medicament.
