An apparatus for administering a substance to a subject, comprising: a housing base; a vial having an inner cylindrical surface and containing the substance, the vial inserted into the housing base; a stopper within the vial, slidably coupled to the vial and being in sliding frictional contact with the inner cylindrical surface, said frictional contact including a rotational friction component (FF R) precluding rotation of said stopper relative to said vial and a linear friction component (FF L) opposing linear advancement of said stopper in a distal direction; a first threaded element rotatable with respect to the vial and substantially linearly immobile in a proximal direction with respect to the vial during rotation of the first threaded element; and a second threaded element threadedly coupled to the first threaded element forming a threaded coupling therebetween, a distal end of the second threaded element being coupled to the stopper and at least the distal end of the second threaded element being substantially non-rotatable relative to the vial, wherein a linear force and a rotational force act on the stopper due to rotation of the first threaded element, the rotation overcoming said linear friction component (FF L) for linearly advancing the second threaded element and the stopper toward a distal end of the vial, and the rotational friction component (FF R) between the stopper and the inner cylindrical surface substantially impedes rotation of the stopper and the second threaded element relative to the first threaded element, characterised in that the threaded coupling between the first threaded element and the second threaded element is within the vial, and in that a vial piercing mechanism is movably coupled to the housing base and a portion of the housing base is configured to displace the first and second threaded elements (26, 28) and the stopper toward the distal end of the vial during insertion into the housing base with the distal end of the vial being inserted into the vial piercing mechanism which pierces a seal at the distal end of the vial, the portion of the housing base also impeding the proximal linear movement of the first threaded element. a housing base; a vial having an inner cylindrical surface and containing the substance, the vial inserted into the housing base; a stopper within the vial, slidably coupled to the vial and being in sliding frictional contact with the inner cylindrical surface, said frictional contact including a rotational friction component (FF R) precluding rotation of said stopper relative to said vial and a linear friction component (FF L) opposing linear advancement of said stopper in a distal direction; a first threaded element rotatable with respect to the vial and substantially linearly immobile in a proximal direction with respect to the vial during rotation of the first threaded element; and a second threaded element threadedly coupled to the first threaded element forming a threaded coupling therebetween, a distal end of the second threaded element being coupled to the stopper and at least the distal end of the second threaded element being substantially non-rotatable relative to the vial, wherein a linear force and a rotational force act on the stopper due to rotation of the first threaded element, the rotation overcoming said linear friction component (FF L) for linearly advancing the second threaded element and the stopper toward a distal end of the vial, and the rotational friction component (FF R) between the stopper and the inner cylindrical surface substantially impedes rotation of the stopper and the second threaded element relative to the first threaded element, characterised in that the threaded coupling between the first threaded element and the second threaded element is within the vial, and in that a vial piercing mechanism is movably coupled to the housing base and a portion of the housing base is configured to displace the first and second threaded elements (26, 28) and the stopper toward the distal end of the vial during insertion into the housing base with the distal end of the vial being inserted into the vial piercing mechanism which pierces a seal at the distal end of the vial, the portion of the housing base also impeding the proximal linear movement of the first threaded element.