US Patent 5,200,196: Scope, Claim Construction, Expiration, and Patent Landscape

US Patent 5,200,196 covers a delayed-release osmotic dosage form. Its independent claim requires a fluid-permeable wall, an internal drug compartment, an outlet, and a drug-free lamina surrounding the drug formulation. The lamina must be 0.1 mm to 10 mm thick and delay drug delivery for up to 12 hours.

The patent is associated with Alza Corporation and the title “Osmotic Dosage Form with Delayed Delivery.” Based on the pre-1995 patent term rules applicable to the patent, its ordinary 17-year term from grant would have ended in 2010. The patent therefore does not present a current U.S. exclusionary right, although its claim remains relevant to prior-art, freedom-to-operate, and patent-family analysis. [1][2]

What does US Patent 5,200,196 protect?

The patent protects a particular architecture for delayed drug delivery rather than a specific active pharmaceutical ingredient.

Claim element	Required feature	Scope implication
Dosage-form context	A chronological dosage form for delivering a beneficial drug	The claim is directed to time-sequenced or delayed drug delivery
Wall	A wall that is at least partly permeable to fluid	The dosage form must permit fluid passage through the wall
Compartment	A compartment enclosed by the wall	The drug formulation must be housed within the dosage form
Drug formulation	A drug-containing formulation in the compartment	The claim is not limited to one active ingredient
Exit means	At least one outlet in the wall	Drug must leave through a defined opening or delivery passage
Delay structure	A drug-free lamina in the compartment	The delay mechanism is a physical layer, not merely a formulation excipient
Lamina thickness	0.1 mm to 10 mm	Thickness is an express numerical limitation
Position	The lamina surrounds the drug formulation	The layer must be positioned between the drug and the release environment
Timing	Delay of up to 12 hours	The claimed structure must produce delayed delivery within the stated period

The claim is best understood as covering a layered osmotic delivery device in which the drug core is enclosed by a drug-free barrier or delay layer. Fluid enters through the permeable wall. The delay layer postpones contact between the ingressing fluid and the drug formulation, or otherwise postpones release through the outlet.

How should claim 1 be construed?

“Chronological dosage form”

“Chronological dosage form” identifies a dosage form designed to release drug according to a time sequence. The term does not necessarily require multiple drug pulses unless other claim language or the specification imposes that requirement. Claim 1 expressly requires at least one delayed delivery event.

A product that releases drug immediately and later releases a second portion could fall within the broader chronological-dosage-form concept if all structural limitations are met. A conventional sustained-release tablet without the claimed surrounding drug-free lamina would generally be outside the supplied claim.

“Wall permeable to the passage of fluid”

The wall must permit fluid movement. In an osmotic system, this commonly means a semipermeable membrane that allows water or another external fluid to enter while restricting passage of the drug and other solutes.

The supplied language does not require the entire wall to be semipermeable. It requires that the wall comprise, at least in part, a composition permeable to fluid. A dosage form with a composite wall could therefore satisfy this limitation if one portion performs the required fluid-permeation function.

“Compartment”

The compartment is the internal space containing the drug formulation and delay structure. The claim does not appear limited to a particular compartment geometry. A cylindrical, multilayer, tablet-like, or capsule-like arrangement could potentially qualify if the wall surrounds the compartment and the drug-free lamina surrounds the drug formulation.

“Exit means”

The claim requires at least one exit means in the wall. The outlet can be analyzed functionally as a passage through which the drug formulation or dissolved drug is delivered.

Because the language uses “means” terminology, the specification may control the interpretation of the outlet structure under 35 U.S.C. § 112(f), depending on the claim’s treatment in the patent and subsequent case law. The relevant scope would then include the structures disclosed in the specification and their equivalents, rather than every conceivable opening. [3]

“Drug-free lamina”

This is the central limitation. The lamina must be:

Located in the compartment.
Free of drug.
Between or around the drug formulation.
0.1 mm to 10 mm thick.
Capable of delaying delivery for up to 12 hours.

A polymeric layer containing no active drug would be the clearest example. The claim does not, from the supplied language alone, require the lamina to be free of all excipients. “Drug-free” ordinarily distinguishes the layer from the drug formulation; it does not necessarily mean chemically empty or free of inactive ingredients.

The word “surrounds” is important. A layer beneath only one face of a tablet may not satisfy the claim if the claim requires circumferential or substantially complete enclosure. A product with a partial barrier may present a noninfringement argument, subject to the specification and prosecution history.

“Up to 12 hours”

The timing limitation can create two separate issues:

Structural infringement: whether the accused lamina has the claimed thickness and placement.
Performance infringement: whether the dosage form delays delivery for the claimed period.

“Up to 12 hours” is potentially broader than a requirement for exactly 12 hours. It may encompass a delay of less than 12 hours, provided the claim and specification support that interpretation. The practical dispute would likely focus on when drug delivery is deemed to begin and what level of drug release constitutes delivery.

What formulations and delivery systems are protected?

The supplied claim primarily protects the dosage-form architecture, not a particular formulation recipe.

Potentially relevant formulations include:

Osmotic drug cores.
Drug-polymer matrices.
Drug suspensions.
Drug solutions or gels.
Solid drug formulations placed within a multilayer tablet.
Formulations used in oral, implantable, or other compartment-based delivery systems.

The claim does not expressly identify:

A particular active ingredient.
A particular polymer.
A particular osmogen.
A specific coating composition.
A defined release rate after the delay period.
A particular tablet shape.
A specific route of administration.

The claim therefore has broad subject-matter reach across active ingredients, but its structural limitations narrow the field to dosage forms with the specified internal drug-free lamina.

How strong is the patent estate for US 5,200,196?

The strength of the patent estate depends on three factors: claim breadth, validity exposure, and remaining term.

Factor	Assessment
Technical concept	Specific and commercially relevant: delayed release through a surrounding drug-free layer
Active-ingredient breadth	Broad because no drug is named
Structural breadth	Moderate to narrow because the lamina must surround the drug formulation
Numerical limitation	Material limitation: 0.1 mm to 10 mm thickness
Functional limitation	Potential disputes over how “delay” and “delivery” are measured
Current enforceability	No current U.S. exclusionary value if the patent expired in 2010
Prior-art value	Potentially significant for later delayed-release and osmotic patents
Product-specific value	Limited without identifying a product that used the claimed architecture during the patent term

The patent would have been more commercially valuable during its term against products using multilayer osmotic tablets or delayed-release cores. Its expiration eliminates ordinary infringement liability for post-expiration commercial activity, but the disclosure can remain relevant to validity challenges and patentability analyses for later applications.

When did US Patent 5,200,196 lose exclusivity?

The patent’s ordinary term would have ended 17 years after its grant date under the pre-Uruguay Round patent-term regime. The grant date was in 1993, placing ordinary expiration in 2010. [1][2]

Milestone	Approximate date or status
Patent grant	1993
Ordinary statutory term	17 years from grant
Expected expiration	2010
Current status	Expired
Patent-term extension relevance	No drug-specific extension should be assumed from the supplied record
Current litigation leverage	None based solely on the expired patent

Patent-term-adjustment rules under 35 U.S.C. § 154 apply principally to applications filed on or after June 8, 1995. They do not ordinarily extend a pre-1995 patent into a current enforceable term. Patent-term extension under 35 U.S.C. § 156 also requires a qualifying regulated product and regulatory history, neither of which is established by the supplied claim. [2][4]

What is the Orange Book status of US Patent 5,200,196?

US Patent 5,200,196 is not inherently an Orange Book patent because it does not identify a marketed drug product, active ingredient, dosage strength, or New Drug Application.

The FDA Orange Book lists patents submitted for approved drug products by NDA holders. A broad drug-delivery patent can be Orange Book-listed only if the NDA holder submitted it in connection with a specific approved product and the patent met applicable listing requirements. The patent number alone does not establish an Orange Book listing. [5]

Accordingly:

No product-specific Orange Book status can be inferred from claim 1.
The patent should not be treated as a current Hatch-Waxman barrier without an identified NDA listing.
A Paragraph IV certification would be relevant only if the patent were listed for a particular reference-listed drug and remained relevant to that product’s regulatory exclusivity.

Did the patent create Paragraph IV or generic-entry risk?

During its term, the patent could have created Paragraph IV risk for a generic or follow-on product using the claimed delayed-release architecture.

A generic applicant would have needed to assess whether its product contained:

A fluid-permeable dosage-form wall.
An internal drug compartment.
A drug formulation.
An outlet.
A drug-free 0.1 mm to 10 mm lamina.
A lamina surrounding the drug formulation.
A delay period within the claimed range.

If the patent had been listed in the Orange Book, a Paragraph IV certification could have triggered patent litigation under the Hatch-Waxman framework. The patent’s expiration removes the current need to design around claim 1 for ordinary U.S. launch purposes, although other patents in the same family or later continuation patents could have separate terms.

Which companies challenged the patent?

The supplied information does not establish a named defendant, Paragraph IV notice, settlement, or reported litigation involving US Patent 5,200,196. No company-specific challenger, settlement date, or court outcome should be attributed to this patent without a litigation record tied to the patent number.

The more relevant commercial parties are:

Alza Corporation, as the identified patent owner or originating technology company.
Generic manufacturers developing delayed-release or osmotic dosage forms.
Pharmaceutical companies licensing Alza delivery technologies.
Later patent holders claiming multilayer tablets, delayed-release barriers, osmotic systems, or chronotherapeutic delivery.

Patent-family review should distinguish direct continuations from merely similar later patents. Similar subject matter does not establish a continuation relationship or common ownership.

How does this patent compare with later delayed-release patents?

Issue	US 5,200,196	Later delayed-release patents
Core concept	Drug-free lamina surrounding drug formulation	May use coatings, rupturable membranes, multilayer matrices, or programmable openings
Drug specificity	Generally drug-agnostic	Often directed to a named active ingredient
Release mechanism	Delayed delivery through internal structural layer	May rely on pH, enzymes, swelling, erosion, osmotic pressure, or timed dissolution
Thickness limitation	0.1 mm to 10 mm	Often uses coating weight, dissolution time, polymer ratio, or membrane thickness
Timing	Up to 12 hours	May claim specific lag times or circadian dosing windows
Current status	Expired	Depends on filing date, continuation chain, and terminal disclaimers

The key distinction is that claim 1 is an internal-layer claim. A later product relying exclusively on an external enteric coating, pH-triggered polymer, or separate capsule shell may not practice the supplied claim, although it could infringe a different patent.

What manufacturing and intellectual-property barriers remain?

The patent’s expiration removes the primary patent barrier created by claim 1. Technical manufacturing barriers may remain.

A manufacturer seeking to reproduce the concept would need to control:

Uniform lamina thickness across the 0.1 mm to 10 mm range.
Concentric or substantially complete placement around the drug formulation.
Mechanical integrity during compression, coating, packaging, and storage.
Reliable fluid ingress and outlet performance.
Consistent lag time across batches.
Drug stability at interfaces between the core and delay layer.
Scale-up of multilayer compression or coating processes.

These manufacturing features may be covered by later patents, trade secrets, process know-how, or device-specific patents even though US Patent 5,200,196 has expired.

What generic launch scenarios apply?

Immediate launch

A generic or branded competitor can generally launch without infringing an expired patent. It must still clear later-expiring patents covering the active ingredient, formulation, manufacturing process, dosage regimen, device, or combination product.

Design-around launch

A product could avoid the supplied claim by omitting or altering one required feature, such as:

Using no drug-free surrounding lamina.
Placing the delay layer outside the wall rather than in the compartment.
Using a drug-containing barrier layer.
Using an external enteric coating.
Using a non-surrounding partial layer.
Using a different delivery architecture.

A design-around does not eliminate risk under unrelated patents.

Litigation-driven launch

Because the patent is expired, current litigation would more likely involve later family members, related patents, or other owners’ patents. The expired patent could be asserted only in limited contexts such as prior-art analysis, ownership disputes, or historical damages questions subject to applicable law.

Key Takeaways

US Patent 5,200,196 covers a delayed-release dosage form with a drug-free 0.1 mm to 10 mm lamina surrounding the drug formulation.
Claim 1 is broad as to the active ingredient but narrower as to dosage-form structure.
The most important limitations are the internal location, drug-free status, surrounding relationship, thickness range, and delay function of the lamina.
The patent does not, from the supplied claim, protect a specific drug, formulation recipe, or commercial product.
Its ordinary U.S. patent term ended in 2010.
The patent should not be treated as a current Orange Book or Paragraph IV barrier without a product-specific listing.
Current launch risk depends primarily on later patents, continuation patents, active-ingredient patents, formulation patents, manufacturing patents, and regulatory exclusivity.
The expired patent remains relevant as prior art and as a technical reference for multilayer osmotic and chronotherapeutic dosage forms.

FAQs

Does US Patent 5,200,196 cover all delayed-release tablets?

No. It requires a specific internal drug-free lamina that surrounds the drug formulation, has a thickness of 0.1 mm to 10 mm, and delays delivery. Conventional enteric-coated or matrix tablets may fall outside the supplied claim.

Does the patent cover a drug-free coating on the outside of a tablet?

Not necessarily. Claim 1 places the drug-free lamina in the compartment and requires it to surround the drug formulation. An external coating may not satisfy those limitations.

Can a product use the same delayed-release concept after the patent expires?

Yes, subject to other unexpired patents. Expiration removes the patent’s exclusionary rights but does not eliminate later patents covering specific drugs, formulations, processes, or delivery devices.

Is a 12-hour delay required to practice claim 1?

The claim states that the lamina delays delivery “for up to 12 hours.” The precise interpretation depends on the claim construction, specification, and prosecution history. A product should not be assessed solely by whether it reaches exactly 12 hours.

Is a drug-free lamina required to contain no excipients?

Not necessarily. “Drug-free” ordinarily means free of the active drug or drug formulation component. The lamina may still contain polymers, binders, osmotic agents, lubricants, or other inactive materials unless the patent specification narrows the term.

References

United States Patent No. 5,200,196, “Osmotic Dosage Form with Delayed Delivery.” U.S. Patent and Trademark Office, 1993.
United States Code, 35 U.S.C. §§ 154, 156. Patent term and patent-term extension provisions.
United States Code, 35 U.S.C. § 112(f). Means-plus-function claim construction.
United States Patent and Trademark Office. Patent term adjustment and patent term calculation guidance.
U.S. Food and Drug Administration. Approved Drug Products with Therapeutic Equivalence Evaluations, commonly known as the Orange Book.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Australia	621030	⤷ Start Trial
Australia	7183787	⤷ Start Trial
Belgium	1000232	⤷ Start Trial
Canada	1297368	⤷ Start Trial
Switzerland	671696	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 5,200,196

Summary for Patent: 5,200,196