Details for Patent: 6,039,974

Summary for Patent: 6,039,974

Title:	Pharmaceutical composition for combination of piperidinoalkanol-decongestant
Abstract:	The present invention provides a pharmaceutical composition in the form of a bilayer tablet comprising,(a) a first discrete zone made with Formulation (A) which comprises, a therapeutically effective decongestant amount of a sympathomimetic drug, or a pharmaceutically acceptable salt thereof, in an amount of about 18% to about 39% by weight of Formulation (A), and a first carrier base material, the first carrier base material comprising a mixture of;(I) carnauba wax in an amount of about 59% to about 81% by weight of Formulation (A); and(ii) a suitable antiadherent in an amount of about 0.25% to about 2.00% by weight of Formulation (A);wherein said first carrier base material provides a sustained release of the sympathomimetic drug; and(b) a second discrete zone made with Formulation (B) which comprises a therapeutically effective antihistaminic amount of a piperidinoalkanol, or a pharmaceutically acceptable salt thereof, in an amount of about 15% to about 30% by weight of Formulation (B) and a second carrier base material, the second carrier base comprising a mixture of;(I) a cellulose diluent in an amount of about 27% to about 73% by weight of Formulation (B);(ii) pregelatinized starch in an amount of about 15% to about 30% by weight of Formulation (B);(iii) a suitable disintegrant in an amount of about 0.25% to about 6.00% by weight of Formulation (B); and(iv) a suitable lubricant in an amount of about 0.25% to about 2.00% by weight of Formulation (B);wherein said second carrier base material provides an immediate release of the piperidinoalkanol or the pharmaceutically acceptable salt thereof.
Inventor(s):	David D. MacLaren, John R. Lefler, Sharon K. Minish
Assignee:	Aventis Pharmaceuticals Inc
Application Number:	US09/127,478
Patent Claim Types: see list of patent claims	Composition; Compound; Dosage form;

United States Drug Patent 6,039,974: Claim Scope, Expiration, Orange Book Status, and Generic Entry Analysis

US 6,039,974 protects a specific bilayer tablet combining sustained-release pseudoephedrine with immediate-release fexofenadine. The patent’s strongest protection is formulation-specific: a carnauba-wax matrix for the decongestant layer and a cellulose, pregelatinized-starch, disintegrant, and lubricant system for the antihistamine layer. The narrowest claims cover a 120 mg pseudoephedrine hydrochloride/60 mg fexofenadine tablet with specified excipient percentages, coating, and hardness.

The patent issued on March 21, 2000, from an application claiming a 1996 priority date. Its original United States patent term ended in December 2016, absent any patent-term adjustment or other term modification. The patent is therefore not a current barrier to generic manufacture. Its principal commercial relevance is historical: it helped protect the Allegra-D 12 Hour formulation and defined the technical formulation space that generic manufacturers later had to assess.

What drug and product does US 6,039,974 protect?

US 6,039,974 covers a bilayer combination tablet containing:

Component	Function	Representative active ingredient
First discrete zone	Sustained release	Pseudoephedrine hydrochloride
Second discrete zone	Immediate release	Fexofenadine hydrochloride
Product strength in claim 11	Combination dose	120 mg pseudoephedrine hydrochloride and 60 mg fexofenadine hydrochloride

The antihistamine is identified through a piperidinoalkanol structure. The compound recited in the dependent claims is fexofenadine hydrochloride, the active antihistamine in Allegra products.

The claim is directed to a dosage form rather than merely to the active ingredients. A tablet containing pseudoephedrine and fexofenadine does not necessarily fall within the claims. It must also have the claimed two-zone architecture, release profiles, and formulation components.

What are the independent claims in US 6,039,974?

Claims 1 and 3 are the principal independent composition claims.

Claim 1: broad bilayer formulation claim

Claim 1 requires a pharmaceutical composition in bilayer-tablet form with two discrete zones.

The sustained-release zone, Formulation A, must contain:

Formulation A limitation	Claimed range
Sympathomimetic drug	About 18% to about 39%
Carnauba wax	About 59% to about 81%
Antiadherent	About 0.25% to about 2.00%
Release profile	Sustained release

The immediate-release zone, Formulation B, must contain:

Formulation B limitation	Claimed range
Piperidinoalkanol antihistamine	About 15% to about 30%
Cellulose diluent	About 27% to about 73%
Pregelatinized starch	About 15% to about 30%
Disintegrant	About 0.25% to about 6.00%
Lubricant	About 0.25% to about 2.00%
Release profile	Immediate release

Claim 1 uses “comprising,” which generally makes the claim open-ended. Additional excipients may be present, but the claimed elements must still be included. The percentages are stated by weight of the applicable formulation, not necessarily by weight of the entire tablet.

Claim 3: narrower formulation ranges

Claim 3 narrows both layers.

For Formulation A, it requires:

• Sympathomimetic drug at about 25% to about 33%;
• Carnauba wax at about 66% to about 74%; and
• Antiadherent at about 0.50% to about 1.50%.

For Formulation B, it requires:

• Piperidinoalkanol at about 15% to about 24%;
• Cellulose diluent at about 43% to about 67%;
• Pregelatinized starch at about 15% to about 24%;
• Disintegrant at about 3.20% to about 4.80%; and
• Lubricant at about 0.50% to about 1.00%.

Claim 3 is materially narrower than claim 1 because it restricts the excipient ratios and the active-ingredient concentration in both layers.

What formulation does claim 11 cover?

Claims 7 through 11 identify the commercial formulation with increasing precision.

Claim 7 specifies pseudoephedrine hydrochloride. Claim 8 identifies:

• Stearic acid as the antiadherent in Formulation A;
• Croscarmellose sodium as the disintegrant in Formulation B; and
• Magnesium stearate as the lubricant in Formulation B.

Claim 9 recites the following formulation percentages:

Formulation A ingredient	Percentage of Formulation A
Pseudoephedrine hydrochloride	About 28.17%
Carnauba wax	About 70.42%
Stearic acid	About 1.15%
Colloidal silicon dioxide	About 0.25%

Formulation B ingredient	Percentage of Formulation B
Fexofenadine hydrochloride	About 17.09%
Cellulose diluent	About 61.67%
Pregelatinized starch	About 17.09%
Croscarmellose sodium	About 3.42%
Magnesium stearate	About 0.75%

Claim 10 identifies the antihistamine as fexofenadine hydrochloride. Claim 11 specifies 60 mg fexofenadine hydrochloride and 120 mg pseudoephedrine hydrochloride.

This creates a layered claim structure:

1. Claim 1 protects the broad bilayer concept.
2. Claim 3 protects narrower percentage windows.
3. Claims 7 through 11 identify the active ingredients and exact commercial strength.
4. Claims 12 and 13 add coating and tablet hardness.

What do claims 4 through 13 add?

Claim	Added limitation
4	Glidant in Formulation A at 0% to about 3.00%
5	Glidant in Formulation A at 0% to about 0.75%
6	Colloidal silicon dioxide as the glidant
7	Pseudoephedrine hydrochloride
8	Stearic acid, croscarmellose sodium, and magnesium stearate
9	Specific ingredient percentages
10	Fexofenadine hydrochloride
11	60 mg fexofenadine and 120 mg pseudoephedrine
12	Coated bilayer tablet
13	Hardness of about 15 kp to about 25 kp

Claims 4 and 5 have an unusual zero lower bound. Because the claims state that the glidant may be present in an amount of 0%, those claims can cover a formulation with no glidant, provided the remaining limitations are met. Claim 6 narrows the glidant to colloidal silicon dioxide but depends on claim 5.

Claim 12 is relatively easy to satisfy because most commercial tablets have some coating. Claim 13 is more technically restrictive because hardness depends on manufacturing conditions, compression force, tooling, tablet geometry, and test method.

How strong is the patent estate for US 6,039,974?

The patent was strong against a product that copied the commercial formulation closely. Its strength came from the combination of structural and functional limitations:

• Bilayer tablet;
• Separate sustained-release and immediate-release zones;
• Carnauba wax as the sustained-release matrix;
• Specific excipient categories;
• Specified active-ingredient ranges;
• Fexofenadine and pseudoephedrine at the commercial dose;
• In some claims, exact excipient percentages.

The patent was weaker against alternative dosage forms and alternative release technologies. A competing product could potentially avoid literal infringement by using:

• A monolithic tablet rather than a bilayer tablet;
• A capsule containing separate pellets;
• A multilayer architecture with materially different zones;
• A different sustained-release polymer;
• A different wax or lipid matrix;
• An immediate-release antihistamine layer using excipients outside the claimed combinations;
• A different active-ingredient ratio or dosage strength.

The doctrine of equivalents could complicate a design-around, particularly where a substitute excipient performs substantially the same function in substantially the same way. Prosecution-history estoppel and the specificity of the issued ranges would limit that argument. The more precisely a claim identifies carnauba wax, excipient percentages, and bilayer structure, the harder it becomes to assert broad equivalence without overcoming the narrowing history.

When did US 6,039,974 lose exclusivity?

The patent’s original term ran for 20 years from the earliest effective nonprovisional filing date. Public patent records identify a 1996 priority date, placing the base expiration in December 2016. The patent is listed in public records as expired.

Event	Date
Earliest priority filing	December 1996
Patent issued	March 21, 2000
Base 20-year term	December 2016
Current enforceability	Expired

Patent expiration removes the patent-based exclusion right. It does not erase historical infringement exposure for conduct occurring before expiration, subject to applicable limitation periods, estoppel, settlement terms, and other defenses.

What was the Orange Book status of US 6,039,974?

US 6,039,974 was associated with the Allegra-D combination product, particularly the 60 mg/120 mg fexofenadine hydrochloride/pseudoephedrine hydrochloride strength. The FDA Orange Book historically listed patents for approved drug products, including patents covering drug substances, formulations, and methods of use where the statutory listing requirements were satisfied.

The practical Orange Book consequences were:

• An abbreviated new drug application applicant had to address any listed patent;
• A Paragraph IV certification could trigger patent litigation;
• A timely infringement action could generate a 30-month stay of approval under the Hatch-Waxman framework;
• The listing did not itself prove that every generic product infringed;
• The FDA did not independently determine claim construction or infringement.

Because US 6,039,974 has expired, it no longer creates a live Orange Book patent obstacle. Current generic risk analysis must focus on any later patents, regulatory exclusivity, labeling restrictions, and non-patent commercial barriers.

Which companies challenged or competed with Allegra-D?

The relevant competitive group included:

• Sanofi and predecessor entities associated with Allegra;
• Aventis and Hoechst Marion Roussel, depending on the period and corporate ownership;
• Teva Pharmaceuticals;
• Perrigo;
• Actavis and related generic businesses;
• Other ANDA sponsors seeking fexofenadine/pseudoephedrine products.

The combination category also faced indirect competition from separate products, including standalone fexofenadine and pseudoephedrine products. A manufacturer did not need to copy the bilayer tablet to compete commercially. It could sell separate dosage forms or use a different combination design, subject to FDA approval and labeling requirements.

Publicly available records do not establish a continuing infringement dispute involving US 6,039,974 after expiration. The principal litigation significance of the patent was during the period when it could support a Paragraph IV action.

What Paragraph IV risks applied to generic manufacturers?

A generic applicant seeking approval before patent expiration could have used one of four certifications:

Certification	Effect
Paragraph I	No patent information listed
Paragraph II	Listed patent already expired
Paragraph III	Approval deferred until patent expiration
Paragraph IV	Patent is invalid, unenforceable, or will not be infringed

For this patent, a Paragraph IV strategy would likely have focused on claim scope rather than the active ingredients alone. Potential arguments included:

• The proposed product was not a bilayer tablet;
• The formulation lacked carnauba wax in the claimed range;
• The antihistamine layer used a different cellulose or starch system;
• The active or excipient percentages fell outside the ranges;
• The product did not provide the claimed sustained-release or immediate-release profiles;
• The patent claims were anticipated or obvious in view of prior combination-tablet technology;
• The patent specification did not adequately support the full breadth of the ranges;
• The claims were indefinite, particularly for functional terms such as “sustained release,” “immediate release,” “suitable,” and “therapeutically effective.”

The strongest noninfringement position would generally be a deliberate formulation change that avoids multiple limitations at once. A one-excipient substitution may be less robust if the remaining structure and release behavior are substantially identical.

What prior-art and validity issues affect the claims?

Obviousness

The invention combines known pharmaceutical elements: pseudoephedrine, fexofenadine, sustained release, immediate release, tablet compression, wax matrices, starch, cellulose, disintegrants, lubricants, and coatings. A validity challenge would argue that the claimed combination was an obvious solution to the known need to pair a long-acting decongestant with an antihistamine.

The patentee’s response would rely on the specific bilayer performance, manufacturing advantages, dose separation, and excipient ranges. Evidence of unexpected release characteristics, improved stability, manufacturability, or commercial success could support nonobviousness, although commercial success would require a nexus to the claimed formulation.

Anticipation

Anticipation would require a single prior-art reference disclosing every limitation of the relevant claim. Claims 9 and 11 are harder to anticipate because they require the detailed ingredient percentages and specific 60 mg/120 mg strength. Claim 1 is broader and therefore more exposed to combination-tablet and sustained-release prior art.

Enablement and written description

The claims cover ranges for multiple excipients and active ingredients. A challenge could contend that the specification does not enable the full scope of every claimed combination, especially where the claims use broad categories such as “sympathomimetic drug,” “cellulose diluent,” “suitable disintegrant,” and “suitable lubricant.”

The narrower claims are less exposed because they correspond more closely to the disclosed composition and commercial embodiment.

Are formulation patents or method-of-use patents more important today?

For this product, formulation claims were more important than method-of-use claims. US 6,039,974 does not primarily claim treatment of allergic rhinitis or nasal congestion. It claims the physical composition and release arrangement.

The patent’s claim categories are:

Patent protection type	Relevance
Bilayer formulation	Core protection
Sustained-release matrix	Core protection for pseudoephedrine zone
Immediate-release antihistamine zone	Core protection
Manufacturing parameters	Limited, through tablet hardness
Coating	Narrow dependent limitation
Method of treatment	Not the principal claim type
Biosimilar protection	Not applicable

Fexofenadine hydrochloride is a small-molecule active ingredient. Biosimilar provisions do not apply. Generic approval proceeds through the ANDA pathway, not the abbreviated biologics pathway.

What manufacturing and intellectual-property barriers existed?

The formulation required more than blending two actives. The manufacturer had to control:

• Separate preparation of the two formulations;
• Compression into discrete layers;
• Carnauba-wax distribution and matrix integrity;
• Immediate disintegration of the fexofenadine layer;
• Sustained pseudoephedrine dissolution;
• Layer adhesion and tablet hardness;
• Coating without compromising release;
• Content uniformity for both layers;
• Stability under storage conditions.

The manufacturing process itself could create practical barriers even after patent expiration. These barriers are not equivalent to patent exclusivity. They relate to scale-up, process validation, dissolution matching, equipment configuration, and FDA approval requirements.

A generic manufacturer could also avoid direct overlap by using a capsule, extended-release beads, an alternative polymer matrix, or a different fixed-dose architecture. The commercial tradeoff would be development cost and the need to demonstrate bioequivalence.

How does US 6,039,974 compare with competing patent strategies?

Strategy	US 6,039,974 approach	Alternative approach
Dosage form	Bilayer tablet	Capsule, monolithic tablet, multilayer tablet
Decongestant release	Carnauba-wax matrix	Polymer, osmotic, coated-pellet, or lipid system
Antihistamine release	Immediate-release layer	Immediate-release granules or separate dosage unit
Active ingredients	Fexofenadine plus pseudoephedrine	Different antihistamine/decongestant combination
Protection focus	Composition and excipient ranges	Drug substance, process, use, or delivery technology
Generic design-around	Change structure and excipients	Develop non-bilayer or non-carnauba formulation

The patent was narrower than a patent claiming any fexofenadine/pseudoephedrine combination, but stronger against a formulation closely corresponding to the disclosed Allegra-D tablet.

What revenue exposure did the patent create?

The patent protected a branded combination product rather than the entire fexofenadine franchise. Revenue exposure was therefore concentrated in the fixed-dose decongestant product, including the 12-hour presentation, rather than standalone Allegra products.

Once the patent expired, revenue risk shifted from patent enforcement to:

• Generic substitution;
• Retail shelf competition;
• FDA approval timing;
• Brand loyalty;
• Product availability;
• Over-the-counter channel dynamics;
• Competing fexofenadine and pseudoephedrine products.

The patent’s expiration removed a principal legal barrier but did not guarantee immediate generic displacement. Manufacturing complexity and market access could still affect launch timing.

Key Takeaways

• US 6,039,974 protects a bilayer tablet containing sustained-release pseudoephedrine and immediate-release fexofenadine.
• Claim 1 is the broadest core claim; claim 3 narrows the excipient and active ranges.
• Claims 7 through 11 identify the commercial 120 mg pseudoephedrine/60 mg fexofenadine formulation.
• Carnauba wax is the central sustained-release matrix limitation.
• The antihistamine layer requires a cellulose diluent, pregelatinized starch, disintegrant, and lubricant.
• Claims 9 and 11 are highly formulation-specific and more difficult to anticipate than claim 1.
• The patent expired in December 2016 based on its 1996 priority date.
• It is not a current patent barrier to ANDA approval or generic launch.
• Biosimilar analysis is irrelevant because fexofenadine and pseudoephedrine are small-molecule drugs.
• The principal historical commercial product was Allegra-D.
• Current competition depends on later patent records, FDA approval status, manufacturing capability, and market access rather than this expired patent.

Frequently Asked Questions

Does US 6,039,974 cover every fexofenadine and pseudoephedrine product?

No. It covers a bilayer tablet with specified sustained-release and immediate-release zones and defined excipient requirements.

Can a generic manufacturer use fexofenadine and pseudoephedrine after expiration?

Yes. The expiration of US 6,039,974 removes the patent restriction created by its claims, subject to any separate unexpired patents or regulatory requirements.

Does replacing carnauba wax automatically avoid infringement?

Not necessarily. For an expired patent, the issue is largely historical. During the patent term, replacing carnauba wax could support noninfringement, but the analysis would depend on the precise claim, prosecution history, and equivalence arguments.

Is claim 13 important for generic product development?

Claim 13 adds a 15 kp to 25 kp tablet-hardness limitation. It could matter for a product closely matching the commercial tablet, but it is narrower than the core bilayer and excipient claims.

Was this patent a drug-substance patent for fexofenadine?

No. US 6,039,974 is a pharmaceutical composition patent. Its subject matter is the bilayer dosage form and formulation architecture, not exclusive ownership of fexofenadine itself.

References

1. United States Patent and Trademark Office. (2000). U.S. Patent No. 6,039,974: Pharmaceutical composition comprising a sustained release decongestant and an immediate release antihistamine. U.S. Department of Commerce.

2. U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations: Orange Book. https://www.fda.gov/drugs/drug-approvals-and-databases/approved-drug-products-therapeutic-equivalence-evaluations-orange-book

3. U.S. Food and Drug Administration. (n.d.). Hatch-Waxman amendments: Abbreviated new drug applications and patent certifications. https://www.fda.gov/drugs/abbreviated-new-drug-application-anda

4. United States Code, 35 U.S.C. § 154. (2024). Contents and term of patent; provisional rights.

5. United States Code, 21 U.S.C. § 355(j). (2024). Abbreviated applications for new drugs.

Drugs Protected by US Patent 6,039,974

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

International Family Members for US Patent 6,039,974

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Argentina	013947
Austria	238773
Australia	725811