Patent: RE43834

Summary for Patent: RE43834

Title:	Injection syringe
Abstract:	The present invention provides an injection syringe comprises a housing including a holder for containing a cartridge of medicine, a piston rod with a non-circular cross-section having an outer thread, a piston rod drive, a one way coupling having an annular ring of internal ratchet notches, which annular ring can be integral with the housing, and a pawl having at least a pair of resilient arms each having a free end.
Inventor(s):	Steenfeldt-Jensen; Soren (Hornback, DK), Hansen; Steffen (Hillerod, DK)
Assignee:	Novo Nordisk A/S (Bagsvaerd, DK)
Application Number:	10/442,855
Patent Claims:	see list of patent claims

Executive summary
United States Patent RE43834 is a reissue covering a mechanical injection/medication delivery pen architecture that integrates (i) a piston rod with a non-circular cross-section and an outer thread, (ii) a drive that translates axial motion into piston-rod rotation in a controlled direction, (iii) a one-way coupling with a ratchet-notched annulus and a resilient-arm pawl that blocks proximal-backdrive while creating an “initial reluctance” before forward rotation, and (iv) a non-self-locking dose-setting thread train that permits dose reduction without pulling the pen apart. The reissue’s independent claim set is broad on architecture but tight on internal mechanics: the specific engagement geometry of the steep-front/ramp-trailing ratchet notches and the resilient pawl arms that abut the steep edge and rest on the ramp are central. The downstream dependent claims further narrow to arm count/spacing, notch edge parallelism, and dose-setting thread behavior. The highest risk for design-around sits in the one-way coupling language and the dose-setting thread train transformation of injection-button axial return into rotational torque that overcomes the one-way “reluctance.”

---

What is US Patent RE43834 and what claims does it cover?

Core independent claim coverage (reissue claim set). RE43834 is written as a layered set of claim “buckets” that span:

1. medication delivery pen architecture with ratchet-based one-way coupling and non-self-locking dose-setting thread train;
2. dose injecting apparatus/injection mechanism architectures where a piston rod drives cartridge expulsion only during injection; and
3. syringe-like injection mechanisms with threaded pitch sections/tube elements and dose scale drum behavior that enable dose reduction without injection.

The reissue’s most commercially material claim features for pens are the coupled requirements that (a) the piston rod is non-circular and driven such that it advances axially distally when the injection button is pressed, while (b) rotation produced by dose setting alone is blocked unless axial force is applied, and (c) the one-way coupling uses an internal ratchet annulus with steep front edges and ramp-shaped trailing edges, in combination with resilient pawl arms whose free-end features abut the steep edge and rest on the ramp to create an initial torque threshold.

Key claim elements mapped to device functions

• Non-circular piston rod + drive coupling:
  • A piston rod having a non-circular cross-section and an outer thread.
  • A first drive part rotatably mounted in the housing mating with the non-circular piston rod so the piston rod rotates with the first part but can move axially independent of the first part.
• Threaded piston rod drive into cartridge:
  • A second housing-fixed part with an internal thread mating the piston rod’s outer thread, converting forward rotation to distal axial advancement inside the cartridge.
• One-way coupling that blocks proximal motion and creates initial reluctance:
  • Annular ring with equally spaced internal ratchet notches.
  • Notch geometry: steep front edge + ramp-shaped trailing edge.
  • Pawl: surrounding piston rod with resilient arms (at least two).
  • Free-end engagement means: features on the arm ends that (i) abut the steep front edges to prevent pawl/first-part rotation in the proximal-causing direction; and (ii) rest on ramp trailing edges to provide initial reluctance that requires sufficient forward rotational torque to overcome.
• Dose setting mechanism that permits dose reduction without disassembly:
  • A “not self locking” thread connection on which an injection button is screwed out by rotating a dose setting element.
  • When the injection button is axially returned (pressed home), axial movement is transformed into rotational torque on the piston rod drive and pawl, but only if torque exceeds the one-way coupling’s reluctance threshold.
  • Claims repeatedly emphasize dose reduction by rotating in the opposite direction without axially pulling the pen apart.

---

Which specific mechanical features of RE43834 are likely to determine infringement?

Infringement tends to turn on the ratchet/pawl geometry and the “initial reluctance” behavior. The reissue’s claim drafting repeatedly couples notch edge geometry (steep front + ramp trailing) with resilient pawl arms that both (i) prevent proximal back-rotation and (ii) create a forward-rotation torque threshold.

One-way coupling: the highest-leverage limitation

The claim language is not satisfied by generic check-valves, simple ratchets without ramp/steep engagement, or pawls that block one direction but do not provide a “reluctance” threshold mechanism.

Critical sub-limitations:

• Internal ratchet notches located on an annular ring on the inside of the housing.
• Notch shape: steep front edge + ramp-shaped trailing edge.
• Pawl behavior:
  • resilient arms with free ends;
  • free ends include engagement means that abut the steep front edge in the blocked direction; and
  • in the forward-driving situation, the engagement rests along the ramp trailing edge to introduce an initial reluctance (requires a sufficiently strong rotational torque to proceed).

Directionality and functional coupling between dose setting and injection

The reissue also recites an operating relationship: during use, the piston rod does not rotate and advance axially when the dose setting member is rotated clockwise or anticlockwise unless axial force is applied to the pen. Only when an axial force is applied by pressing an injection button home does the axial force get transformed into rotation that advances the piston rod distally.

A design that allows piston-rod rotation (and distal advance) solely from dose setting rotation, without the “axial force transformation” gating, likely escapes the specific functional limitation.

Thread train requirement: “not self-locking” dose reduction

The dose setting thread connection must be “not self-locking,” enabling a set dose to be reduced in size without axially pulling apart any parts. The reissue ties this to a screw-out of the injection button by rotation, followed by an axial return that generates rotational torque to overcome the one-way coupling reluctance.

---

How many distinct claim “themes” are in RE43834, and how do they compare?

Three themes appear across the reissue claim set you provided:

Theme A: Pen with non-circular piston rod + ratchet-pawl initial reluctance + non-self-locking dose setting

This is the dominant set for pen delivery systems. It anchors on:

• non-circular cross-section piston rod;
• housing-fixed internal thread part;
• rotatable drive part mating to non-circular rod;
• one-way coupling with stepped/ramped notch and resilient pawl arms;
• dose setting thread train that is not self locking, plus dose reduction capability without disassembly.

Theme B: Injection devices where piston rod rotates only during injection

This theme emphasizes that the piston rod rotates only during injection of medication, and dose setting rotation alone does not drive axial advancement unless axial force is applied.

This can overlap with Theme A but is broader in that it emphasizes rotational timing rather than fully specifying the notch geometry, depending on claim wording.

Theme C: Syringe-like injection mechanisms with pitch-differentiated threads and tube-driven rotation

This theme introduces alternative structural drivers:

• piston rod with distinct threaded sections having different pitches;
• tube that engages a thread on the piston rod to form a not self-locking connection;
• axial tube motion without rotation induces piston-rod rotation, which then advances axially via a thread element fixed relative to the housing;
• dose scale drum that rotates toward zero during injection;
• ability to reduce wrongly set doses by reversing dose dial rotation before injection.

These are mechanically adjacent to the pen architecture (thread conversion of motion), but they are not identical. In litigation, different implementation variants often land in different claim groupings.

---

What do the dependent claims add to the scope (arm geometry and notch relationships)?

Arm count and spacing (Claims 2, 7)

• “Two or more arms” disposed with the same relative spacing around the pawl circumference.

Design-around pressure: if a competitor uses an asymmetric pawl arm layout or an arm system not equally spaced, they can argue non-infringement of the dependent feature. Whether that fully avoids the independent claim depends on how the independent claim is phrased relative to arm count/spacing.

Notch steep front edge parallelism (Claims 3, 8)

• Steep front edges of internal notches on opposite sides are parallel.

Arm circumferential extension + engagement means shape (Claims 4-5, 9-10)

• Arms extend circumferentially from the pawl body.
• Engagement means at the arm free end is the end-surface opposite the pawl, abutting the steep notch front edge.
• Alternative: engagement means includes a protrusion.

These dependent claims are usually less important than the independent “steep edge/ramp trailing edge with resilient pawl arms” concept, but they narrow variants.

---

When does RE43834 lose exclusivity (how to estimate expiration)?

No expiration timetable can be produced from RE43834 alone using the information provided. To compute term end dates, one needs the underlying application filing dates and reissue-specific data (USPTO reissue/continuation lineage). Your prompt includes claim text but not the patent bibliographic data required for expiration analysis.

---

What is the patent estate strength for RE43834’s technology (design-around and risk profile)?

Strength: high around the one-way coupling and injection gating

RE43834’s claim architecture is coherent and specific:

• It does not just claim “ratchet prevents reverse”; it claims a ratchet notch shape (steep front edge + ramp trailing edge) plus resilient pawl arms with two positional relationships (abutting steep edge vs resting on ramp) and an “initial reluctance” torque threshold.
• It also ties motion gating to a dose-setting rotation that alone does not advance axially without axial force and injection-button transformation.

These are implementation-specific and reduce the set of easy workarounds.

Weakness: breadth depends on interpretation of “in situation of use” and the transform of axial force

Where claim language includes “in situation of use” functional outcomes, courts may require that accused products meet the functional gating under normal operation. Competitors that restructure the dose setting mechanism to directly rotate the drive in a way that changes the gating function may narrow their risk.

---

What generic entry risks exist for devices covered by RE43834?

This is a device patent, not a drug substance patent. “Generic entry” maps in practice to:

• competing injection pens / syringe devices selling the same therapeutic drug (often with unchanged administration requirements); and
• device design that substitutes non-infringing mechanics.

The primary entry risk is not “drug generics” but device-competition that attempts to copy the architecture. The highest litigation risk sits with competing insulin or GLP-1 delivery pens if their internal mechanics include:

• non-circular piston rod with thread-drive inside a cartridge;
• ratchet-and-pawl one-way coupling with steep/ramp notch geometry and initial reluctance threshold; and
• dose reduction without disassembly through a not self-locking thread train.

---

Which companies are challenging this space with similar pen injection architectures?

No company-by-company landscape can be produced from the information provided. Without assignees, related family members, and prosecution/infringement markers, mapping challengers would be speculative.

---

What formulations or dosage forms are covered?

The claims are for delivery devices, not drug formulations. The reissue repeatedly frames a “cartridge containing a medication” and a “conduit connected to said cartridge.” There are no claim limitations on the chemical formulation of the medication, excipients, concentration, or dosage strength beyond the device’s ability to expel multiple doses or set a dose size.

---

What regulatory status issues arise for devices like this?

Regulatory status cannot be determined from claim text alone. Orange Book is for approved drugs and certain device-drug combination listings. For a device patent, typical regulatory hooks are FDA device approval pathways (510(k), De Novo, PMA) or combination product review if applicable, but none of that is present in the prompt.

---

How does RE43834 compare with adjacent mechanical injection IP patterns?

Comparison to generic “ratchet pawl” pen concepts

Many injection pens include:

• ratchets for one-way dosing;
• dose dials and injection buttons;
• threaded piston rods.

RE43834 distinguishes itself by requiring:

• notch geometry (steep front edge and ramp trailing edge) and engagement behavior that creates initial reluctance; and
• specific coupling between dose setting rotation and axial force transformation.

Comparison to tube-based axial-to-rotation syringe mechanics

Theme C in your claim list (tube non-self-locking connections and pitch-differentiated thread sections) resembles a broader family of injection mechanisms where axial movement induces rotation via a threaded tube interface. A competitor adopting tube-driven mechanics could avoid the exact pen ratchet coupling, depending on which independent claim is asserted and whether the accused device has the “steep/ramp” and resilient-arm features.

---

Key Takeaways

• RE43834’s enforceable core is the one-way coupling combining internal ratchet notches with steep front edges and ramp-shaped trailing edges, plus a resilient-arm pawl that both blocks proximal back-rotation and creates initial reluctance requiring torque to overcome.
• The second core is dose setting vs injection gating: dose setting member rotation alone does not rotate/advance the piston rod unless an axial force is applied by pressing an injection button home, converting axial return into torque that drives the distal advance.
• The third core is dose reduction without disassembly via a not self-locking thread connection that allows reversal of dose setting.
• Dependent claims narrow arm spacing, notch edge relationships, and engagement geometry, tightening design-around options for close variants.

---

FAQs

1. Does RE43834 require the piston rod to have a non-circular cross-section?
   Yes in the pen-focused independent claim language you provided: the piston rod has a non-circular cross-section and mates with a first rotatable part.

2. Can a design with a different one-way mechanism still infringe RE43834?
   Infringement risk is highest where the device replicates the steep-edge/ramp-trailing-edge ratchet notch geometry with resilient pawl arms that abut the steep edge and rest on the ramp to create initial reluctance.

3. Is dose reduction capability a necessary feature for infringement?
   For the pen/dose-setting dependent structure in the provided claims, yes: claims emphasize reduction without axially pulling the pen apart using a not self-locking thread connection.

4. Does the claim cover devices where dose setting drives axial advancement without pressing?
   The operating limitation in the provided claims indicates the piston rod does not rotate and advance axially during dose setting rotation unless axial force is applied.

5. Are drug formulations (active ingredient chemistry) limited by RE43834?
   No. The claims are directed to the delivery mechanism and cartridge handling, not the chemical formulation.

---

References (APA)

1. United States Reissue Patent RE43834 (claim text provided in prompt).

Details for Patent RE43834

Applicant	Tradename	Biologic Ingredient	Dosage Form	BLA	Approval Date	Patent No.	Expiredate
Novo Nordisk Inc.	NOVOLOG	insulin aspart	Injection	020986	June 07, 2000	RE43834	2023-05-21
Novo Nordisk Inc.	NOVOLOG	insulin aspart	Injection	020986	January 19, 2001	RE43834	2023-05-21
Novo Nordisk Inc.	NOVOLOG	insulin aspart	Injection	020986	April 23, 2004	RE43834	2023-05-21
Novo Nordisk Inc.	NOVOLOG	insulin aspart	Injection	020986	October 31, 2013	RE43834	2023-05-21
Novo Nordisk Inc.	NORDITROPIN	somatropin	Injection	021148	June 20, 2000	RE43834	2023-05-21

International Patent Family for US Patent RE43834

Country	Patent Number	Estimated Expiration
South Africa	99714
World Intellectual Property Organization (WIPO)	9938554
United States of America	6004297
United States of America	6235004
Ukraine	56256