A drug delivery assembly includes a main body and a cartridge. The body includes a housing, an adhesive pad, and a body interface that detachably associates with a cartridge interface of the cartridge. A fluid flow path extends through the body housing, between a first end configured to open a seal of the cartridge and a second end configured to enter a human body. The cartridge contains a drug reservoir having an outlet and holding a medicament. The seal prevents the medicament from exiting the reservoir and maintains pressure within the reservoir until the seal is opened by the first end of the fluid flow path when the cartridge is coupled to the main body, placing the reservoir into fluid communication with the flow path. A controller actuates a valve within the body to selectively allow and prevent flow through the flow path during an automated drug delivery routine.