Delivery device for drug pellets
There is provided a device for dispensing one or more drugs in pellet form, including a cartridge including a chamber for containing a plurality of drugs in pellet form, a screw pump configured to receive pellets from the chamber and, upon rotation of the screw pump, transport the pellets from the chamber to be dispensed from the device via the screw pump, and a rotating member extending through the cartridge and configured to rotate the screw pump so as to dispense pellets therefrom.
1. A handheld and portable medicament dispenser, comprising:
a housing that includes an electromechanical actuator, and a battery configured to power the electromechanical actuator; and
one or more replaceable medicament cartridges insertable into the housing, wherein each replaceable medicament cartridge comprises in one replaceable unit:
a chamber containing a plurality of free flowing medicament pellets each having a largest dimension of between about 150 μm and about 1500 μm;
a screw pump configured to receive pellets from the chamber and, upon rotation of the screw pump, transport the pellets from the chamber to be dispensed from the dispenser via the screw pump;
a rotating member extending through the cartridge and configured to rotate the screw pump so as to dispense pellets therefrom;
a valve connected to an outlet of the screw pump and configured to close the screw pump so as to prevent pellets from being dispensed from the screw pump outside of a dispensing operation when the screw pump is not being rotated, and to permit pellets to be dispensed from the screw pump during a dispensing operation upon rotation of the screw pump; and
a plunger movable along the rotating member and driven so as to force the pellets contained within the chamber towards the screw pump as it moves along the rotating member, so as to pack them within the chamber towards the screw pump;
wherein the replaceable unit of each cartridge, including at least the chamber, the screw pump, and the rotating member, is insertable into the housing and such that the rotating member of each cartridge physically connects to the electromechanical actuator when the replaceable unit of each cartridge, including at least the chamber, the screw pump, and the rotating member, is inserted into the housing, wherein upon such physical connection a rotary force can be transferred from the actuator to the rotating member during a dispensing operation to transport the pellets from the chamber to be dispensed from the dispenser via the screw pump as aforesaid;
wherein the plunger is configured to press onto the medicament pellets within the chamber and force the medicament pellets towards the dispensing end of the cartridge to pack the medicament pellets tightly within the chamber as the rotating member rotates during each dispensing operation, and outside of a dispensing operation the valve prevents the medicament pellets that are packed tightly within the chamber from running through and leaking from the screw pump by providing a resistive force to the medicament pellets; and
wherein the actuator is configured such that upon actuation thereof the actuator causes the rotating member to rotate by a predetermined amount, wherein by virtue of the pellets being tightly packed within the chamber as aforesaid the predetermined amount of rotation corresponds to a precise volume of the medicament pellets, and therefore a precise dose, to be dispensed.
2. The handheld and portable medicament dispenser as claimed in claim 1 , wherein the valve flexes open to allow pellets to be dispensed as the screw pump rotates during each dispensing operation, and then flexes back when the screw pump is not rotating, so as to stop pellets falling out of the screw pump outside of a dispensing operation.
3. The handheld and portable medicament dispenser as claimed in claim 1 , wherein the screw pump is configured to transport the pellets from the chamber to outside of the cartridge by rotation of the screw pump without linear translation of the rotating member.
4. The handheld and portable medicament dispenser as claimed in claim 1 , wherein the valve comprises an outlet for dispensing the pellets therefrom, and the valve is configured such that pellets need to be forced out of the valve, through the outlet, upon rotation of the rotating member during a dispensing operation.
5. The handheld and portable medicament dispenser as claimed in claim 4 , wherein a surface of the plunger forms one end of the chamber, such that as the plunger moves along the rotating member in use the volume of the chamber gradually decreases.
6. The handheld and portable medicament dispenser as claimed in claim 5 , wherein each cartridge comprises a unitary piece having the same cross-section extending the entire length of the chamber, the interior of which forms the walls of the chamber.
7. The handheld and portable medicament dispenser as claimed in claim 1 , wherein the replaceable unit includes at least all of the chamber, the screw pump, and the rotating member integrated as a single unit as the rotating member physically connects to the actuator upon insertion of the replaceable unit into the housing.
8. The handheld and portable medicament dispenser as claimed in claim 1 , wherein the replaceable unit includes at least all of the chamber, the screw pump, and the rotating member integrated as a single unit during the insertion of the replaceable unit into the housing, including to physically connect the rotating member and the electromechanical actuator, as aforesaid.
9. The handheld and portable medicament dispenser as claimed in claim 1 , wherein the chamber has a length, and wherein each cartridge comprises a unitary piece comprising a portion having a same cross-section extending at least the entire length of the chamber, the interior of which forms the walls of the chamber.
10. The handheld and portable medicament dispenser as claimed in claim 9 , wherein the unitary piece extends from the portion having the same cross-section to an exit tube of reduced width that comprises a screw thread.
11. The handheld and portable medicament dispenser as claimed in claim 1 , wherein the rotating member of each cartridge and the electromechanical actuator physically connect as aforesaid by virtue of a male connecting member interfacing with and mechanically connecting to a female connecting member.
12. The handheld and portable medicament dispenser as claimed in claim 1 , wherein the valve comprises a resilient member that flexes open to allow pellets to be dispensed as the screw pump rotates during each dispensing operation, and then flexes back when the screw pump is not rotating, so as to stop pellets falling out of the screw pump outside of a dispensing operation.
13. The handheld and portable medicament dispenser as claimed in claim 12 , wherein the pellets each have a largest dimension of between about 500 μm and about 1100 μm.
14. The handheld and portable medicament dispenser as claimed in claim 1 , wherein the screw pump has a screw thread with a channel depth, and wherein the channel depth of the screw thread is between about 1.1 and about 4 times the largest dimension of the pellets.
15. The handheld and portable medicament dispenser as claimed in claim 1 , wherein the screw pump has a screw thread with a flight width, and wherein the flight width of the screw thread, defined as the pitch minus the channel width, is less than about 10 times the largest dimension of the pellets.
16. The handheld and portable medicament dispenser as claimed in claim 13 , wherein the screw pump has a screw thread with a channel depth, and wherein the channel depth of the screw thread is between about 1.1 and about 4 times a largest dimension of the pellets.