External drug pump
Apparatus is described for administering a substance to a subject. A vial contains the substance and a stopper is disposed within the vial and is slidably coupled to the vial. A first threaded element is (a) rotatable with respect to the vial 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. At least a distal end of the second threaded element is substantially non-rotatable with respect to the vial, and the distal end of the second threaded element defines a coupling portion that couples the second threaded element to the stopper. The first threaded element, by rotating, linearly advances the stopper and at least the distal end of the second threaded element toward a distal end of the vial. Other embodiments are also described.
1. An activation mechanism for a drug delivery device wearable by a patient, the activation mechanism comprising:
a base having a patient contact surface;
a hollow sleeve disposed on the base, the hollow sleeve having first and second ends and extending along a longitudinal axis between the first and second ends, the hollow sleeve having a holding portion, the holding portion extending generally longitudinally from the first end of the sleeve, the holding portion having a retaining surface arranged opposite to the first end of the sleeve, the retaining surface facing the patient contact surface of the base and extending generally perpendicularly with respect to the longitudinal axis, the retaining surface being positioned between the first end of the sleeve and the patient contact surface of the base;
a longitudinally extending needle having a sharp end and an opposed end;
a needle holder coupled to the opposed end of the needle and being movable along the longitudinal axis with respect to the sleeve between a withdrawn position, wherein the sharp end of the needle is disposed within the base, and an injection position, wherein the sharp end of the needle extends beyond the patient contact surface of the base;
a spring coupled to the needle holder and biasing the needle holder to the withdrawn position;
a longitudinally extending cannula having a free end and being sized to coaxially receive the needle therein;
a cannula holder coupled to the cannula opposite the free end thereof and movable along the longitudinal axis between a retracted position, wherein the free end of the cannula is disposed within the base and at least a portion of the cannula holder is disposed between the first and second ends of the sleeve, and an extended position, wherein the free end of the cannula extends beyond the patient contact surface of the base, and
wherein the retaining surface of the holding portion abuts a generally radially extending ledge of the cannula holder when the needle holder is in the withdrawn position and the cannula holder is in the extended position to prevent relative movement of the cannula holder to the retracted position.
2. The activation mechanism of claim 1 , wherein the spring surrounds at least a portion of the needle.
3. The activation mechanism of claim 1 , wherein when the needle holder is in the withdrawn position, the sharp end of the needle is disposed within the cannula holder.
4. The activation mechanism of claim 1 , wherein the needle holder includes a retention surface that is oriented generally parallel to the patient contact surface and is in contact with the spring.
5. The activation mechanism of claim 1 , wherein a portion of the needle holder is disposed within the cannula holder when the needle holder is in the injection position and the cannula holder is in the extended position.
6. The activation mechanism of claim 1 , wherein a portion of the needle holder is disposed within the cannula holder when the needle holder is in the withdrawn position and the cannula holder is in the retracted position.