This invention relates to the parenteral administration of solid drug compositions. In particular the invention relates to an external, wearable device for the automatic, controlled administration of a solid drug composition to a patient comprising: a housing (32,34); a plunger (36) located within said housing; a dispensing tube (40) attached to said housing, said tube being designed to contain a solid drug composition consisting essentially of said drug and up to 50%, by weight, of a pharmaceutically acceptable carrier; an actuator (54) arranged within said housing to move said plunger from said housing into said dispensing tube; a controller that acts on said actuator to regulate the movement of said plunger through said housing and into said dispensing tube; and a power source (52) arranged to provide energy to said actuator and said controller; wherein said plunger moves the solid drug composition out of said dispensing tube at a controlled rate.