Details for Patent: 6,446,627

Summary for Patent: 6,446,627

Title:	Inhaler dose counter
Abstract:	A dose counter for a metered dose inhaler comprises actuator means (341), drive means (350) for driving a rotary gear (360) in step-wise fashion in response to displacement of said actuator means (341), said rotary gear (360) comprising a wheel having a plurality of ratchet teeth (not shown) around its periphery. Means (364) are provided to prevent reverse rotation of the rotary gear (360). A flexible tape (368) is provided with a visible array of incrementing integers on its surface indicating the number of medicament doses remaining in the inhaler. The tape (368) indexes by a single integer in response to each step of the step-wise rotary motion of the rotary gear (360). A control surface (371) regulates the position of engagement and disengagement between the drive means (350) and the rotary gear (360). In an alternative embodiment (FIG. 6), the control surface (371) is omitted and the means for preventing reverse rotation comprise a stepless restraint (664).
Inventor(s):	Nicholas John Bowman, Michael John Holroyd, Costaninos Panayi, William Richard Treneman
Assignee:	Norton Healthcare Ltd
Application Number:	US09/319,947
Patent Claim Types: see list of patent claims	Use; Delivery;

United States Patent 6,446,627: Claim Scope, Expiration, and Metered-Dose Inhaler Patent Landscape

US 6,446,627 protects mechanical dose-counter architectures for metered-dose inhalers, particularly counters using a ratcheted rotary wheel, a visible numerical display, a pawl-driven indexing mechanism, and a mechanism that prevents reverse rotation. The patent is directed to the counter assembly rather than the inhaled drug, formulation, propellant, canister, or metering valve.

The patent term has ended. Its claims therefore do not create current blocking patent risk for an inhaler manufacturer, generic applicant, or device supplier, although the claimed architecture remains relevant for freedom-to-operate searches, historical infringement analysis, and patent-family landscaping.

What does US Patent 6,446,627 cover?

The patent covers a dose counter integrated with, or operably associated with, a metered-dose inhaler. Its technical architecture has five principal elements:

1. An actuator responsive to movement associated with dose delivery.
2. A rotary wheel mounted on a spindle.
3. Ratchet teeth positioned around the wheel periphery.
4. A drive mechanism that advances the wheel incrementally.
5. A display that exposes one numerical dose count after each indexing step.

The claims add two principal anti-reversal concepts:

• A friction clutch, including a wrap-spring clutch.
• A stepless restraint mechanism, specifically a wrap-spring clutch in several claims.

The claims also cover a particular pawl structure, called a "straddle drive," in which the ratchet-engaging element is supported between two spaced support arms.

The patent does not claim a particular active pharmaceutical ingredient, inhalation formulation, propellant, canister coating, metering valve, dose size, or therapeutic indication. The claims are device claims focused on dose-counting mechanics. (U.S. Patent No. 6,446,627)

Which claims are independent in US 6,446,627?

Claims 1, 5, 10, 12, 18, 24, and 29 are independent claims. The remaining claims depend from those claims and add specific structural or operational limitations.

Independent claim	Core subject matter	Main narrowing feature
1	Counter with rotary ratchet wheel, actuator, display, control surface, and reverse-rotation prevention	Reverse-rotation prevention is a friction clutch
5	Counter with rotary wheel, display, actuator, and stepless restraint	Wrap-spring clutch acting on the spindle
10	Counter using a rack and ratchet-drive pawl	Straddle-drive pawl
12	Counter with control surface and reverse-rotation prevention	Straddle-drive pawl
18	Counter with control surface and reverse-rotation prevention	Flexible web display
24	Counter with stepless restraint	Straddle-drive pawl
29	Counter with stepless restraint	Flexible web display

The claim set is highly repetitive. It appears designed to preserve multiple combinations of the same principal elements:

• Friction clutch plus control surface.
• Wrap-spring clutch plus spindle restraint.
• Straddle pawl plus rotary ratchet wheel.
• Flexible numerical display web.
• Spring-loaded plunger actuated by movement of the medicament reservoir.
• Counting on either the forward or return stroke of the actuator.

How broad are the independent claims?

Claim 1: friction-clutch counter with control surface

Claim 1 requires a dose counter having:

• An actuator.
• A ratcheted rotary wheel.
• Stepwise drive.
• Reverse-rotation prevention.
• A numerical display.
• A control surface regulating engagement and disengagement between the drive and wheel.
• A friction clutch as the reverse-rotation prevention mechanism.

The claim is broader than claims requiring a wrap-spring clutch because "friction clutch" can encompass more than one clutch configuration. It is narrower than a generic ratchet counter because the claim requires a friction-based anti-reversal structure and a control surface that governs pawl engagement.

A product using only a conventional detent pawl or a separate fixed stop may avoid the friction-clutch limitation, depending on the construction of "reverse rotation prevention means" and the physical operation of the accused mechanism.

Claim 5: wrap-spring clutch on the spindle

Claim 5 shifts the focus from a control surface to a "stepless restraint means." It expressly requires a wrap-spring clutch operating on the spindle that carries the ratcheted wheel.

This limitation is technically significant. A wrap-spring clutch generally permits rotation in one direction and grips or braces against rotation in the opposite direction. The claim does not merely require an anti-backlash feature. It requires the claimed type of stepless restraint, with the spring clutch acting on the wheel spindle.

A counter using a torsion spring, friction pad, elastomeric brake, pawl stop, or one-way bearing would not literally satisfy the wrap-spring-clutch limitation, although the doctrine of equivalents could have been relevant before expiration.

Claim 10: rack-and-pawl implementation

Claim 10 differs materially from the other independent claims. It recites a rack having an array of ratchet teeth and a straddle-drive pawl engaging the rack.

The claim appears directed to a linear rack arrangement rather than only the peripheral teeth of the rotary wheel. The engagement element is supported between two arms, and dependent claim 11 requires the gap between those arms to accommodate the thickness of the rack.

This creates a structural limitation that is potentially useful in infringement analysis. A single-sided pawl, a molded flexible finger, or a pawl engaging a circumferential wheel without a rack may fall outside claim 10, subject to the interpretation of "rack" and "straddle drive."

Claims 12, 18, 24, and 29: combination claims

These claims combine subsets of the patent's mechanical features:

• Claim 12 combines the control surface and straddle-drive pawl.
• Claim 18 combines the control surface and flexible web display.
• Claim 24 combines stepless restraint and straddle-drive pawl.
• Claim 29 combines stepless restraint and flexible web display.

Because each independent claim contains a combination of limitations, infringement requires the accused counter to contain every limitation of at least one asserted claim. A product can therefore avoid one claim while remaining exposed to another if it uses a different combination of clutch, pawl, display, or actuator features.

What dependent limitations matter most?

What is the significance of the wrap-spring clutch claims?

Claims 2, 15, 16, 21, 22, 25, and 30 narrow the anti-reversal mechanism to a wrap-spring clutch. Claims 5, 24, and 29 already include wrap-spring-clutch limitations in their independent claim structures, while the dependent claims reinforce the specific spindle arrangement.

The important technical distinction is between:

• A clutch that prevents reverse rotation continuously and without discrete stops.
• A ratchet or detent that prevents reverse rotation only at selected angular positions.

The patent claims the first type in its "stepless restraint" language.

What is the significance of the straddle-drive pawl?

Claims 3, 8, 12, 23, and 33 require an engagement element supported between spaced arms. This configuration may improve alignment, reduce pawl deflection, or stabilize engagement with the ratchet teeth.

The structural limitation has two parts:

1. An engagement element that contacts the ratchet teeth.
2. Support for that element between two spaced arms.

A pawl that is supported only on one side may present a non-infringement position. A U-shaped, forked, or bifurcated pawl may present greater risk if its central engagement element is supported between the arms.

What is the significance of the flexible web display?

Claims 4, 9, 17, 18, 28, and 29 cover an elongate flexible web carrying printed or written dose numbers.

This language is narrower than a general numerical display. It points to a flexible strip, belt, or web that moves relative to a viewing window. A molded rotating drum, electronic LCD, printed disk, or seven-segment display may avoid the flexible-web limitation.

What is the significance of the spring-loaded plunger?

Claims 7, 14, 20, 26, and 32 recite a spring-loaded plunger that engages the rim of a medicament reservoir. The plunger is depressed when the reservoir translates to actuate the metering valve.

This limitation ties the counter to a particular inhaler actuation geometry. A counter actuated by:

• A dose-button movement.
• A lever.
• Canister pressure.
• Valve-stem displacement.
• A separate electronic sensor.

may not satisfy the spring-loaded-plunger limitation.

When does the counter index?

Claims 6, 13, 19, 27, and 31 permit indexing on either the forward stroke or return stroke of the actuator. This language broadens the operational timing of the counter and prevents a design-around based solely on changing the point in the actuation cycle at which the count advances.

What is the patent's expiration status?

US 6,446,627 is expired. It cannot currently support an infringement action or block commercial manufacture, sale, or use of a counter based on the issued claims.

The patent issued in 2002. Under the modern patent-term rule, utility patents generally expire 20 years from the earliest effective nonprovisional filing date, subject to patent-term adjustment, patent-term extension, terminal disclaimers, and certain transitional rules. A patent issuing in 2002 from the late-1990s or early-2000s filing period would have reached the end of its ordinary term no later than the early 2020s. (35 U.S.C. § 154)

Issue	Assessment
Patent type	Utility patent
Technology	Mechanical dose counter for a metered-dose inhaler
Current enforceability	Expired
Drug exclusivity	None
Formulation exclusivity	None
Device claim scope	Ratchet wheel, clutch, pawl, actuator, and display combinations
Current blocking risk	None from this patent
Historical relevance	High for inhaler-counter prior-art and family analysis

Any patent-term-adjustment calculation would affect the precise expiration date, but not the present conclusion that the patent term has ended.

Does US 6,446,627 have Orange Book listings?

No Orange Book listing should be expected for this patent. The claims cover a mechanical inhaler counter, not an active ingredient, dosage form, formulation, or method of using a drug.

The FDA Orange Book generally identifies patents submitted for approved drug products under the Hatch-Waxman framework. Device patents may be relevant to a drug-device combination product, but a standalone mechanical counter patent does not become an Orange Book-listed drug patent merely because it is used with an inhaler. (FDA, 2024)

The practical consequences are:

• The patent does not create a listed patent against which a generic applicant must certify under Paragraph IV.
• The patent does not generate a Hatch-Waxman 30-month stay.
• It does not provide drug exclusivity.
• It does not establish exclusivity for a specific inhaled corticosteroid, bronchodilator, propellant, or combination product.

Are Paragraph IV challenges or biosimilar risks relevant?

Paragraph IV challenges

Paragraph IV certification is generally irrelevant to this expired device patent. A generic applicant may still evaluate inhaler-device patents in a broader freedom-to-operate analysis, but US 6,446,627 is not a current patent obstacle and is not the type of active listed drug patent that ordinarily supports a Paragraph IV dispute.

Biosimilar risk

Biosimilar law is not relevant. The patent does not claim a biologic product, a biosimilar, a manufacturing cell line, a protein sequence, or a biologic formulation. Its technology could be used with an inhaled biologic in theory, but the patent's legal subject matter remains the mechanical counter.

What patent landscape surrounds inhaler dose counters?

The relevant landscape has four technology groups.

Technology group	Typical protection	Relationship to US 6,446,627
Mechanical rotary counters	Ratchets, gears, pawls, clutches, printed number wheels	Directly overlapping technical field
Linear counters	Racks, sliders, plungers, flexible strips	Overlaps the rack and web embodiments
Electronic counters	Sensors, microcontrollers, displays, dose-event memory	Usually outside the core mechanical claim language
Integrated inhaler systems	Counter plus canister, valve, actuator, or dose-confirmation system	May create separate device patent rights

Later patent families may claim different mechanisms, including electronic sensing, dose-event detection, low-dose warnings, reset prevention, canister presence detection, and integration with inhaler housings. Those later rights must be analyzed separately by jurisdiction, assignee, continuation status, and expiration date.

US 6,446,627 should therefore be treated as an expired foundational mechanical-counter reference, not as a current representative of the full patent estate for modern smart inhalers or connected inhalation devices.

Which companies and products could have historical relevance?

The patent's technology is relevant to manufacturers and suppliers of:

• Metered-dose inhaler actuators.
• Disposable and reusable dose counters.
• Canister-and-actuator assemblies.
• Printed flexible counter webs.
• Ratchet and pawl mechanisms.
• One-way and wrap-spring clutch components.

The patent does not, by itself, establish that any particular marketed inhaler infringed. Product-level analysis would require an element-by-element comparison of the counter's internal structure, including the type of anti-reversal mechanism, pawl support geometry, display format, and actuator path.

Large inhaler manufacturers, contract device manufacturers, and specialist inhaler-component suppliers may have owned related patents or licensed counter technology. Ownership of a related patent family does not establish ownership of US 6,446,627, and commercial use of a similar counter after expiration does not create current infringement liability under this patent.

What generic launch risks remain after expiration?

US 6,446,627 creates no current generic launch barrier. Residual risk may arise from other rights, including:

• Patents covering the active pharmaceutical ingredient.
• Formulation and propellant patents.
• Valve and canister patents.
• Inhaler housing and actuator patents.
• Dose-indicator patents filed after the relevant priority date.
• Manufacturing-process patents.
• Regulatory exclusivity for the reference drug.
• Trademarks, trade dress, and device branding.

A generic inhaler can therefore be free of risk under US 6,446,627 while remaining exposed to unrelated patents or regulatory barriers.

How strong is the patent estate represented by US 6,446,627?

The estate was technically focused and commercially relevant during its term, but its present legal strength is zero because the patent is expired.

During the enforceable period, the claims had several characteristics:

• Broad functional coverage of the counter's major subsystems.
• Multiple independent claims directed to alternative combinations.
• Specific fallback positions for wrap-spring clutches.
• Specific fallback positions for straddle-drive pawls.
• Coverage of both rotary and rack-based indexing concepts.
• Coverage of printed flexible-web displays.
• Coverage of forward-stroke and return-stroke counting.

Its principal weakness was design-around potential. A competitor could seek to replace the wrap-spring clutch, use electronic sensing, change the pawl geometry, use a fixed drum or LCD display, or actuate the counter through a different part of the inhaler.

Key Takeaways

• US 6,446,627 claims mechanical dose counters for metered-dose inhalers.
• The central elements are a ratcheted rotary wheel, incremental drive, numerical display, actuator, and reverse-rotation restraint.
• The most important narrowing features are the wrap-spring clutch, straddle-drive pawl, flexible display web, control surface, and spring-loaded reservoir-engaging plunger.
• Claims 1, 5, 10, 12, 18, 24, and 29 are independent.
• The patent is expired and creates no current blocking patent risk.
• It is not a drug, formulation, biologic, or Orange Book patent.
• Paragraph IV and biosimilar analyses are not materially relevant to this patent.
• Current inhaler launch risk must be assessed against later device, formulation, valve, actuator, manufacturing, and drug patents.

FAQs About US 6,446,627

What device does US 6,446,627 protect?

It protects mechanical dose-counter arrangements for metered-dose inhalers, including ratcheted wheels, pawls, clutches, actuators, and numerical displays.

Does US 6,446,627 cover an inhaled drug?

No. The claims cover the counter mechanism, not the active ingredient, formulation, propellant, or therapeutic use.

Can a company still be sued for practicing the claims?

No current infringement action can be based on the expired patent. Historical conduct during the enforceable term presents a separate legal question.

Does a wrap-spring clutch automatically infringe the patent?

No. The entire claim must be satisfied. The clutch type is only one limitation, and the accused product must also contain the required actuator, wheel, drive, display, and other claimed structures.

Is a flexible dose-counting strip required for every claim?

No. The flexible web is required only in claims that expressly recite it, including claims 4, 9, 17, 18, 28, and 29 or their relevant combinations.

References

1. U.S. Patent No. 6,446,627. (2002). Dose counter. United States Patent and Trademark Office.

2. United States Code, Title 35, Section 154. (2024). Contents and term of patent; provisional rights.

3. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations. U.S. Department of Health and Human Services.

Drugs Protected by US Patent 6,446,627

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate

Foreign Priority and PCT Information for Patent: 6,446,627

Foriegn Application Priority Data
Foreign Country	Foreign Patent Number	Foreign Patent Date
United Kingdom	9626538	Dec 20, 1996

PCT Information
PCT Filed	December 18, 1997	PCT Application Number:	PCT/GB97/03480
PCT Publication Date:	July 02, 1998	PCT Publication Number:	WO98/28033

International Family Members for US Patent 6,446,627

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Austria	268619
Australia	5329298
Germany	69729485
Denmark	0966309
European Patent Office	0966309