Abstract: Provided herein are systems, devices, kits, and methods for administering liquid drug formulation by titratable subcutaneous or intramuscular administration.

Abstract: Apparatus is described for administering a substance to a subject. A vial contains the substance, an inner surface of the vial being shaped to define a protrusion therefrom. A stopper within the vial is slidably coupled to the vial. A first threaded element is (a) rotatable and (b) substantially immobile proximally with respect to the vial during rotation of the first threaded element. A second threaded element is threadedly coupled to the first threaded element. The protrusion impedes rotation of the second threaded element with respect to the vial. The distal end of the second threaded element remains proximal to a distal end of the stopper during rotation of the first threaded element. The first threaded element, by rotating, linearly advances the stopper and the second threaded element toward a distal end of the vial. Other embodiments are also described.