Telescoping plunger rod

1. A plunger rod for use with a syringe, the plunger rod comprising:

an outer housing having a proximal end and a distal end opposite the proximal end, and further defining a lumen between the proximal end and the distal end; and

an inner body configured to be movable within the lumen between a first position and a second position along an axial direction, the inner body comprising a retention member extending outward from the inner body in a direction angularly offset from the axial direction,

wherein, when the inner body is in the first position relative to the outer housing, the plunger rod has a first length, and, when the inner body is in the second position relative to the outer housing, the plunger rod has a second length greater than the first length, and

wherein, when the inner body is in the first position relative to the outer housing, the inner body is precluded from being rotated relative to the outer housing, and when the inner body is in the second position relative to the outer housing, the inner body is configured to be rotated relative to the outer housing until the retention member is received within a channel of the outer housing to preclude the inner body from moving relative to the outer housing in the axial direction.

2. The plunger rod of claim 1 , wherein the outer housing defines a plurality of channels, including the channel, that are spaced along the axial direction, each of the plurality of channels being configured to receive the retention member.

3. The plunger rod of claim 2 , wherein the plurality of channels include a distal channel, the channel is an intermediate channel adjacent the distal channel, and the retention member is configured to be received in the distal channel when the inner body is in the first position relative to the outer housing.

4. The plunger rod of claim 3 , wherein the plurality of channels include a proximal channel spaced from the distal channel and the intermediate channel, the proximal channel configured to receive the retention member therein, and

wherein, when the retention member is received in the proximal channel, the inner body is precluded from being rotated relative to the outer housing.

5. The plunger rod of claim 3 , wherein the distal channel is tapered in the axial direction towards the distal end of the outer housing.

6. The plunger rod of claim 1 , wherein the outer housing defines a contact surface in communication with the lumen, the contact surface contacting a face defined on the inner body after the inner body is rotated relative to the outer housing to the second position.

7. The plunger rod of claim 6 , wherein the face of the inner body and the contact surface of the outer housing are in a friction fit when the face is in contact with the contact surface to resist relative rotation between the inner body and the outer housing.

8. The plunger rod of claim 6 , wherein the contact surface includes a retention member contact surface and an inner body contact surface,

wherein the face of the inner body is defined by the distal end of the inner body and by the retention member, and

wherein the retention member contact surface is configured to contact the portion of the face defined by the retention member, and the inner body contact surface is configured to contact the portion of the face defined by the inner body that does not define the retention member.

9. The plunger rod of claim 8 , wherein, when the inner body is in the second position, the inner body is configured to receive an axial force applied thereto and to transfer the axial force therefrom to the outer housing via the contact between the face of the inner body and the contact surface of the outer housing.

10. The plunger rod of claim 6 , wherein the contact surface includes a lower contact surface and an upper contact surface spaced from the lower contact surface, wherein the retention member of the inner body is configured to be received into a space defined between the upper contact surface and the lower contact surface and to be in friction fit with the upper contact surface and the lower contact surface.

11. The plunger rod of claim 6 , wherein one of the contact surface and the face of the inner body defines a notch thereon, and the other of the contact surface and the face defines a protrusion thereon, and

wherein, when the inner body is rotated relative to the outer housing while the inner body is in the second position, the protrusion is receivable in the notch.

12. The plunger rod of claim 11 , wherein rotation of the inner body relative to the outer housing in a first rotational direction causes the protrusion to be moved into the notch, such that the protrusion is configured to contact at least one wall of the notch to preclude rotation of the inner body relative to the outer housing in a second rotational direction opposite the first rotational direction.

13. The plunger rod of claim 11 , wherein the protrusion is disposed on the face, and the notch is disposed on the contact surface of the outer housing.

14. The plunger rod of claim 11 , further comprising a plurality of the protrusions and a plurality of the notches, wherein the number of the plurality of the protrusions is the same as the number of the plurality of the notches.

15. The plunger rod of claim 1 , wherein the retention member includes a base extending from the inner body and a resilient protrusion extending from the base,

wherein the resilient protrusion is configured to be deformed by application of a force, and resiliently undeforms upon removal of the force.

16. The plunger rod of claim 15 , wherein the outer housing defines a detent extending into the lumen that is configured to be contacted by the retention member,

wherein, upon contact with the detent, the resilient protrusion is configured to deform due to the contact and due to application of the force, such that the retention member is moved past the detent, and

wherein the resilient protrusion resiliently returns to its original configuration when the resilient protrusion is moved past the detent to prevent separation of the inner body from the outer housing based on interaction between the resilient protrusion and the detent.

17. The plunger rod of claim 1 , further comprising a plunger disposed adjacent to the distal end of the outer housing, such that the plunger is configured to contact a liquid within the syringe to cause dispensing thereof from the syringe.

18. A syringe assembly comprising:

a syringe configured to receive a liquid therein;

a plunger rod configured to be slidably received within the syringe, the plunger rod including:

an outer housing having a proximal end and a distal end opposite the proximal end, and further defining a lumen between the proximal end and the distal end; and

an inner body configured to be movable within the lumen between a first position and a second position along an axial direction, the inner body comprising a retention member extending outward from the inner body in a direction angularly offset from the axial direction; and

a plunger disposed on the outer housing,

wherein, when the inner body is in the first position relative to the outer housing, the plunger rod has a first length, and, when the inner body is in the second position relative to the outer housing, the plunger rod has a second length greater than the first length, and

wherein, when the inner body is in the first position relative to the outer housing, wherein, when the inner body is in the first position relative to the outer housing, the inner body is precluded from being rotated relative to the outer housing, and when the inner body is in the second position relative to the outer housing, the inner body is configured to be rotated relative to the outer housing until the retention member is received within a channel of the outer housing to preclude the inner body from moving relative to the outer housing in the axial direction.

19. The syringe assembly of claim 18 , wherein the liquid comprises an active ingredient, the active ingredient comprising at least one of a therapeutic agent, a diagnostic agent, or a nutrient.

20. The syringe assembly of claim 19 , wherein the active ingredient is selected from the group consisting of an opioid, benzodiazepine, α2-adrenergic receptor agonist, beta blocker, morphine, hydromorphone, hydrocodone, oxycodone, oxymorphone, codeine, buprenorphine, naloxone, naltrexone, fentanyl, remifentanil, sufentanil, alfentanil, meperidine, rocuronium, vecuronium, midazolam, lorazepam, diazepam, neostigmine, atropine, glycopyrrolate, dexmedetomidine, cisastracurium, ropivacaine, lidocaine, propofol, ketamine, succinylcholine, moxifloxacin, linezolid, levofloxacin, levetiracetam, vancomycin, cefepime, aztreonam, cefoxitin, ceftriaxone, cefazolin, cefotaxime, ceftazidime, gentamicin, oxacillin, nafcillin, penicillin, cefuroxime, ticarcillin, clavulanic acid, piperacillin, tazobactam, azithromycin, meropenem, ertapenem, tigecycline, micafungin, metronidazole, fluconazole, itraconazole, posaconazole, heparin, enoxaparin, dalteparin, theophylline, acetaminophen (paracetamol), ibuprofen, acetylcysteine, decitabine, azacitidine, docetaxel, pemetrexed, palonosetron, aprepitant, fosaprepitant, famotidine, amiodarone, nitroglycerin, nicardipine, clevidipine, dobutamine, esmolol, labetalol, metroprolol, somatropin, liraglutide, abaloparatide, semaglutide, teriparatide, degarelix, sumatriptan, epinephrine, ephedrine, vasopressin, methotrexate, testosterone, and hydroxyprogesterone.

21. A method of dispensing of a liquid from a syringe barrel using a plunger rod having an outer housing and an inner body receivable within the outer housing, the plunger rod having a proximal end and a distal end spaced from the proximal end along an axial direction, the method comprising:

moving the inner body relative to the outer housing in the axial direction from a first position to a second position away from the proximal end to expand the plunger rod to an extended configuration, wherein the inner body is precluded from being rotated relative to the outer housing while being moved in the axial direction from the first position to the second position;

rotating the inner body relative to the outer housing to prevent axial movement of the inner body relative to the outer housing when the inner body is in the second position; and

applying an axial force to the inner body to cause the plunger rod to move relative to the syringe barrel.

22. The method of claim 21 , wherein the plunger rod has a first length measured between the proximal end and the distal end when the inner body is in the first position, and a second length greater than the first length measured between the proximal end and the distal end when the inner body is in the second position.

23. The method of claim 21 , wherein the outer housing includes a contact surface, and the inner body includes a face, and wherein rotating the inner body relative to the outer housing when the inner body is in the second position includes axially aligning the contact surface with the face such that the contact surface and the face to contact each other to prevent axial movement of the inner body relative to the outer housing.

24. The method of claim 21 , further comprising inserting the plunger rod into the syringe barrel, such that the plunger rod is configured to be slidably moved within the syringe barrel.

25. The method of claim 21 , further comprising, prior to expanding the plunger rod to the extended configuration, inserting the inner body into the outer housing, wherein the inner body is precluded from being rotated relative to the outer housing while being moved into the outer housing.

26. The plunger rod of claim 4 , wherein the first position is the distal most position of the inner body within the lumen of the outer housing.

27. The plunger rod of claim 4 , wherein the distal channel and the proximal channel are circumferentially offset.