Patent: 5,599,323

Summary for Patent: 5,599,323

Title:	Syringe system
Abstract:	An insulin injection system comprises a pen shaped syringe with a cartridge containing insulin, and an injection needle. The needle is a G30 needle and the insulin is a type which may freely flow through a G 30 needle. When the insulin is the type comprising suspended crystals the maximal dimension of any crystal is 15 .mu.m.
Inventor(s):	Bonnichsen; Frits F. (Lynge, DK), J.o slashed.rgensen; Peter N. (Broenshoej, DK)
Assignee:	Novo Nordisk A/S (Bagsvaerd, DK)
Application Number:	08/550,494
Patent Claims:	see list of patent claims

United States Patent 5,599,323: Needle Assembly for Pen-Type Insulin Delivery Using a G30 Needle

What does US 5,599,323 claim, in operational terms?

US 5,599,323 claims a needle assembly built for pen-type insulin syringes that use a standard removable needle fitting and accept insulin-type cartridges that can flow freely through a G30 needle. The core hardware is a G30 needle mounted in a needle hub with defined geometry that supports a two-portion needle configuration and depth control during injection.

Claim 1: Core structure and constraint set

Claim 1 defines:

• (a) Needle hub
  • Has a base
  • Includes a standard insulin needle fitting for removably mounting on a pen-type insulin syringe
  • The fitting is defined by compatibility with standard mounting and cartridges that flow freely through a G30 needle
• (b) Needle
  • G30 needle secured in the base
  • Needle has first and second needle portions extending from the base in opposite directions

This yields a functional picture: the hub accepts a standard pen fit; the needle is G30 and is configured as a two-sided needle with portions extending in opposite directions from a hub base.

Claim 2: Threaded annular sleeve on the fitting

Claim 2 limits Claim 1 by adding:

• The “standard fitting” includes an annular sleeve extending from the hub base
• The sleeve surrounds the first needle portion concentrically and is spaced from it
• The sleeve has a threaded interior
• The interior threads allow the sleeve to be screwed onto the externally threaded hub-receiving part of a pen syringe

This is a specific mechanical interface claim: concentric spaced sleeve + internal threads that mate with an externally threaded pen hub.

Claim 3: Predetermined needle length for patient injection

Claim 3 adds:

• The second needle portion has a predetermined length suitable for injecting insulin into a human patient

This is a dimensional limitation that can affect both design-around and obviousness analysis.

Claim 4: Depth-control geometry via a central protrusion embedding the needle

Claim 4 adds depth-control structure:

• The base further comprises a central protrusion extending from the base along the second needle portion for a predetermined distance
• This protrusion embeds the second needle portion along that distance
• The second needle portion ends in an exposed end that projects axially from the protrusion
• The exposed end length corresponds to the desired depth of needle insertion into a human patient

Claim 4 thus converts “predetermined length” (Claim 3) into a constructed exposure depth: insertion depth is controlled by the embedded length inside a central protrusion and the remaining exposed tip length.

---

How broad are these claims, and what is actually doing the limiting?

Claim 1 limitations that drive scope

The strongest narrowing elements in Claim 1 are:

1. G30 needle (size is explicit)
2. Two-portion needle geometry (first and second portions extend from the base in opposite directions)
3. Pen compatibility via a “standard insulin needle fitting” that mounts on pen-type insulin syringes using a “standard mounting”
4. Cartridge flow requirement through a G30 needle (a functional materials/compatibility constraint)

The breadth is still moderated by the “standard fitting” language, but Claim 1 never fully enumerates what makes the fitting “standard” beyond compatibility with pen syringes having a “standard mounting” that accepts insulin cartridges that can flow through a G30 needle.

Claim 2 limits the fitting to a threaded sleeve interface

Claim 2 narrows further by requiring:

• an annular sleeve
• concentric spacing around a specific needle portion (the first portion)
• threaded interior
• screw-on engagement with externally threaded hub-receiving part on the pen

That combination is a clear design constraint and a clear litigation fulcrum: an accused device without a threaded annular sleeve (or without the sleeve concentrically surrounding and spaced from the first needle portion) is less likely to land inside Claim 2.

Claim 4 creates an injection-depth control feature

Claim 4 is both structural and functional:

• A central protrusion that embeds a section of the second needle portion
• An exposed needle end projecting out from the protrusion
• The exposed end length corresponds to desired insertion depth

This means infringement depends on whether a device controls needle exposure depth using an embedded segment in a protrusion (not just a generic needle guard or fixed length).

---

What would a design-around look like, claim-by-claim?

Claim 1: Replace the two-sided needle arrangement or eliminate G30

• G30 substitution: moving to a different gauge is a straightforward workaround because Claim 1 requires a G30 needle.
• Single-direction needle: if the needle does not have first and second portions extending in opposite directions from the base, it likely avoids Claim 1.
• Needle hub interface: avoiding the “standard insulin needle fitting” geometry or the removal/mounting interface may avoid the claim, but the claim language is compatibility-focused and could still capture close equivalents if the interface is treated as “standard.”

Claim 2: Remove the threaded annular sleeve interface

• Use a fitting that is snap-fit, bayonet, or otherwise non-threaded relative to the annular sleeve.
• Use a sleeve that does not surround the first needle portion concentrically or not with the required spacing.
• Provide an interface with internal threads located elsewhere, not as “threaded interior” of an annular sleeve extending from the base.

Claim 3: Change the effective injection length

• Adjusting the second needle portion length away from the “predetermined length appropriate for injecting insulin” is less clean as a design-around because the phrase can be argued as functional and may map to typical injection lengths. The design-around is strongest if the device has a clearly different exposure/insertion scheme that makes the second portion length not “appropriate” under the claim’s construction.

Claim 4: Avoid the embedded needle section in a central protrusion that sets exposed length

• Remove the central protrusion embedding the needle portion for a predetermined distance.
• Use a different exposure control method (e.g., a sliding shield, fixed guard, or a different geometry where the needle exposure length is not produced by embedding within a central protrusion).
• If the exposed length is controlled by another structural feature rather than the protrusion geometry, the claim narrows out.

---

How does the prior art likely map to these claims?

The claim set is built around a needle technology + pen needle interface + insertion depth control. In the absence of the full prosecution file for US 5,599,323, the most reliable analytical approach is to map the claim elements to common disclosure buckets that exist in the pen-needle landscape:

1. Pen-type insulin syringe needle hubs with standardized detachable needle attachments
2. Gauge-specific microneedles (including widely used pen-needle sizes)
3. Needle-in-hub configurations that may use concentric sleeves, threads, or other mating features
4. Injection depth control via guards, sleeves, or embedded geometry

The claims are drafted so that each element corresponds to a known patentable theme:

• Claim 2 is tied to threaded screw-on mounting.
• Claim 4 is tied to depth control via embedding and exposed tip length.

This structure implies the patent’s novelty was likely argued on the combination of pen interface + needle geometry + depth exposure geometry rather than on the mere use of a G30 needle.

---

Patent landscape implications: where US 5,599,323 sits relative to typical competition

Likely adjacency in the market

Pen needles are typically implemented with:

• Threaded external connections on pen hubs (often using standardized luer-like/needle-attachment conventions or proprietary thread interfaces depending on manufacturer).
• Needle assemblies that include a guard or insertion depth setting feature.
• Needle sizes including common gauges, with G30 historically present in several markets.

Accordingly, US 5,599,323 is most likely relevant to:

• Vendors whose pen needles use threaded interfaces with annular sleeves
• Devices that implement needle exposure depth via embedded needle length in a central element
• Configurations where the needle is structurally arranged into two portions extending oppositely from a base

Litigation risk profile by claim

• Highest risk: devices that match Claim 2 and Claim 4 together, because those are specific and likely less common as a combined mechanical design.
• Moderate risk: devices that match Claim 1 (G30 + two-direction needle portions) but differ in depth control.
• Lower risk: devices that use different needle exposure control and avoid the central protrusion embedding geometry.

---

Claim construction pressure points (what will determine infringement outcomes)

“Standard insulin needle fitting”

This phrase is likely treated as a limitation tied to the pen’s expected standard mounting interface. If an accused product’s attachment is substantially different but still works functionally with pen syringes, disputes may shift toward whether the interface qualifies as “standard” in the claim sense.

“First and second needle portions extending from said base in opposite directions”

This is a crisp structural element. Any design that uses a conventional single-ended needle in a hub may avoid this element entirely. Two-sided needles are uncommon in pen delivery products, so this may be a major differentiator.

“Annular sleeve ... concentrically and spaced”

This is a structural relationship. “Spaced therefrom” is measurable. A sleeve that directly contacts the needle, or that surrounds without a gap, risks non-infringement.

“Central protrusion ... embeds ... predetermined distance”

Embedding requires the needle portion to be inserted into or surrounded by the protrusion such that a segment is not exposed. Devices that use external guards without embedding, or that set exposure via other spacing mechanisms, may avoid Claim 4.

---

Critical assessment of the claim strategy

Strengths

• The claims stack limitations in a way that targets a specific assembly: G30 + two-sided needle + threaded sleeve + depth embedding geometry.
• Claim 4 provides a distinctive depth-setting structure that can support non-obviousness arguments over generic guard-based needle exposure.

Vulnerabilities

• Claim 1 includes a functional compatibility limitation tied to insulin cartridges “that may flow freely through a G30 needle.” That invites arguments about whether the claim can be read to cover cartridges with different flow behavior, or whether the “flow freely” language is indefinite or functional without clear boundaries.
• “Standard mounting” and “standard insulin needle fitting” invite construction fights. If a large portion of the industry uses multiple “standard” interfaces, scope can expand or contract depending on how those words are interpreted.

---

Key takeaways

• US 5,599,323 is a pen-needle assembly patent centered on a G30 needle arranged into opposite-direction needle portions and mounted through a standard pen fitting.
• Claim 2 narrows the attachment interface to a threaded annular sleeve that is concentric and spaced around the first needle portion and screw-engages an externally threaded pen hub.
• Claim 4 narrows injection mechanics to a central protrusion that embeds the needle portion for a predetermined distance and defines insertion depth through the exposed tip length.
• For competitive devices, the highest infringement leverage lies in matching the threaded annular sleeve interface and the central protrusion embedded-depth geometry together, while avoiding design differences in those features is the clearest path to non-infringement.

---

FAQs

1) What is the single most limiting element in Claim 1?

The claim requires a G30 needle with first and second needle portions extending in opposite directions from the hub base, which is uncommon compared with single-ended needle assemblies.

2) Does Claim 2 require the needle hub to be threaded?

Yes. Claim 2 requires a fitting that has an annular sleeve with a threaded interior for screwing onto a pen syringe part with an externally threaded hub-receiving portion.

3) How does Claim 4 control needle insertion depth?

It uses a central protrusion that embeds a portion of the second needle portion. The exposed end that projects from the protrusion defines the desired insertion depth via its length.

4) Could an identical device be designed around by changing gauge?

Changing away from G30 is a clean design-around for Claim 1 and all dependent claims.

5) Which claim pair is most likely to matter in enforcement?

The combination of Claim 2 (threaded annular sleeve interface) and Claim 4 (central protrusion embedded depth control) is the most specific and therefore the most enforcement-relevant configuration.

---

References

[1] United States Patent 5,599,323. “Needle assembly for pen-type insulin syringe.” (Claim text as provided in user prompt).

Details for Patent 5,599,323

Applicant	Tradename	Biologic Ingredient	Dosage Form	BLA	Approval Date	Patent No.	Expiredate
Eli Lilly And Company	HUMULIN R U-100	insulin human	Injection	018780	October 28, 1982	5,599,323	2015-10-30
Eli Lilly And Company	HUMULIN R U-500	insulin human	Injection	018780	December 29, 2015	5,599,323	2015-10-30
Eli Lilly And Company	HUMULIN R U-100	insulin human	Injection	018780	August 06, 1998	5,599,323	2015-10-30
Eli Lilly And Company	HUMULIN R U-500	insulin human	Injection	018780	March 31, 1994	5,599,323	2015-10-30
Eli Lilly And Company	HUMULIN R U-100	insulin human	Injection	018780	May 25, 2018	5,599,323	2015-10-30
Baxter Healthcare Corporation	MYXREDLIN	insulin human	Injection	208157	June 20, 2019	5,599,323	2015-10-30