Share This Page
Details for Patent: 4,017,615
✉ Email this page to a colleague
Summary for Patent: 4,017,615
| Title: | Propylene carbonate ointment vehicle | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Abstract: | An ointment vehicle containing from 0.5 to 30 percent propylene carbonate, from 30 to 99.5 weight percent petrolatum and/or polysiloxane, compatible cosolvent, the concentration of which in combination with propylene carbonate is from 0.5 to 70 percent, and, optionally, surfactants, thickeners, preservatives, and penetrants. This ointment is a suitable vehicle for all types of therapeutic agents for topical application including antibiotics, steroids, antihistamines, antiseptics, anesthetics, antibacterials, fungicides and the like, and has shown particular advantages with anti-inflammatory topical corticoids. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Inventor(s): | Subramaniam Shastri, Zafaruzzaman I. Shaikh | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Assignee: | Syntex Pharmaceuticals International Ltd | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Application Number: | US05/639,740 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
Patent Claim Types: see list of patent claims | Compound; | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Patent landscape, scope, and claims: | US Drug Patent 4,017,615: Claim Scope, Expiration, Formulation Coverage, and Patent LandscapeUS Patent 4,017,615 covers topical ointments containing propylene carbonate, a defined hydrophobic ointment base, a compatible co-solvent, and a propylene-carbonate-soluble medicament. Claims 2 through 7 narrow the invention to topical corticosteroids and four specifically identified steroid compounds. The patent issued on April 12, 1977, and its ordinary 17-year patent term would have expired on April 12, 1994, absent an unusual terminal-disclaimer or term-adjustment issue. It does not create a current US exclusivity barrier for generic or follow-on topical products.[1] What does US Patent 4,017,615 protect?The patent protects a composition, not the underlying steroid molecules, a particular branded product, or a method of treating a named disease. Its central inventive concept is the use of propylene carbonate in an ointment vehicle to solubilize and deliver a medicament, particularly a topical corticosteroid. The independent claim requires all of the following:
The claim is compositionally broad because it covers multiple vehicle systems, optional excipients and any therapeutically effective medicament that is soluble in propylene carbonate. Claims 2 through 7 then focus the protection on corticosteroid formulations. How broad is claim 1 of US 4,017,615?Claim 1 is a combination claim with several potentially important limitations. “Consisting essentially of”The phrase “consisting essentially of” generally permits additional ingredients if they do not materially alter the basic and novel characteristics of the composition. The basic characteristics appear to be:
A formulation containing an additional excipient would not automatically fall outside the claim. The question would be whether that ingredient materially changes the composition’s relevant properties, such as solubilization, ointment character, stability or topical delivery. The phrase creates more uncertainty than the closed term “consisting of.” It also makes formulation-by-formulation infringement analysis important. A generic product could not avoid the claim merely by adding a preservative, antioxidant or other conventional excipient if the resulting formulation retained the claimed basic characteristics. Propylene carbonate limitationThe claim requires 0.5% to 30% propylene carbonate by weight. A formulation containing less than 0.5% or more than 30% would fall outside this numerical limitation, subject to ordinary claim-construction and equivalents analysis. Because the patent is expired, the doctrine-of-equivalents issue has no current commercial significance for US enforcement. Petrolatum and polysiloxane limitationThe base must include petrolatum, a polysiloxane having the specified viscosity range, or a mixture of the two. The claim therefore does not cover every propylene-carbonate-containing topical preparation. Creams, gels, lotions or emulsions lacking the claimed petrolatum or polysiloxane base would generally require separate analysis. The polysiloxane viscosity range is unusually broad. The supplied claim text appears to omit a superscript and likely means 10^6 centistokes rather than “106 centistokes.” That drafting issue affects technical interpretation but not the patent’s present legal status. Co-solvent limitationClaim 1 requires a compatible co-solvent, with the co-solvent and propylene carbonate together accounting for 0.5% to 70% by weight. The claim does not identify a closed list of co-solvents. The term “compatible” is functional and would ordinarily be interpreted in view of the specification, examples and technical context. Potential co-solvent categories could include polyols, glycols, alcohols or other solvents compatible with the ointment base and active ingredient. The exact scope would depend on the patent’s specification and prosecution history. Optional excipientsSurfactants, thickeners and penetrants are expressly optional. Their absence does not avoid claim 1. Their presence is permitted within the stated numerical limits. The penetrant limitation is particularly important. Because the claim states “from 0 to 25 weight percent,” a formulation does not need a penetration enhancer to satisfy the claim. The same applies to surfactants and thickeners. What do claims 2 through 7 add?Claims 2 through 7 narrow claim 1 by specifying topical anti-inflammatory steroids.
A product satisfying claim 4, 5, 6 or 7 must also satisfy every limitation of claim 1 and the intervening limitations of claims 2 and 3. The species claims do not independently cover the named steroids in all dosage forms. They cover those steroids only when formulated in the claimed propylene-carbonate ointment system. How expansive is the steroid Markush claim in claim 3?Claim 3 uses a structural Markush definition. It identifies a pregn-4-ene-3,20-dione nucleus or a substituted pregn-4-en-20-one pyrazole nucleus and allows numerous alternatives at positions C-1, C-2, C-6, C-7, C-9, C-11, C-16, C-17 and C-21. The claim permits substantial substitution, including:
The genus is therefore materially broader than claims 4 through 7. It is designed to cover a class of corticosteroid structures sharing the claimed steroidal or steroid-pyrazole framework, rather than one commercial active ingredient. The principal technical limitation is not merely steroid identity. The steroid must be soluble in propylene carbonate and used in a therapeutically effective amount in the claimed ointment base. A steroid falling within the structural Markush formula but lacking the required solubility or formulation characteristics would not satisfy the full combination claim. What compounds are covered by claims 4 through 7?The supplied chemical names identify four corticosteroid species:
The chemical names should be matched against the original patent drawings, CAS records and regulatory substance records before assigning modern generic names. The claim language, rather than a commercial synonym, controls infringement analysis. When did US Patent 4,017,615 lose exclusivity?The patent issued on April 12, 1977.[1] Under the pre-TRIPS US patent-term regime, utility patents generally received 17 years from issuance. On that basis, the patent expired on April 12, 1994.
The patent predates the Hatch-Waxman Act and the modern 20-year term measured from the earliest effective nonprovisional filing date. Patent-term adjustment was not part of the ordinary regime applicable to a 1977-issued patent. No current US exclusivity should be attributed to this patent. What is the Orange Book status of US 4,017,615?US Patent 4,017,615 is not itself a current Orange Book exclusivity asset. The patent issued seven years before the Hatch-Waxman Act created the modern Orange Book patent-certification framework.[2] An Orange Book listing is tied to an approved drug application and the NDA holder’s submitted patent information. A patent can cover a formulation or method of use without creating current Orange Book protection if it is expired, was never listed, or is not associated with the relevant NDA. For a generic topical corticosteroid, the relevant regulatory questions would include:
Patent 4,017,615 should not be treated as a current Paragraph IV obstacle. Any generic applicant evaluating a product today would need to examine later patents associated with the specific reference product, not rely on this 1977 patent.[3] Are Paragraph IV challenges relevant to this patent?A current Paragraph IV challenge directed solely to US 4,017,615 would have no practical blocking effect because the patent expired in 1994. Paragraph IV certification addresses listed patents that could otherwise be infringed by an ANDA product. An expired patent cannot support a present injunction against launch based on ordinary patent rights. The historical significance is different. During the patent’s life, a formulation applicant could have faced infringement risk if its product contained:
That historical risk ended with patent expiration. What formulations are protected by US 4,017,615?The patent is directed to ointments rather than every topical delivery system. Likely within the historical claim scopeA formulation would have presented the strongest infringement risk if it contained:
Potentially outside the claim scopeThe following formulation changes could avoid literal claim coverage, depending on the complete formulation and claim construction:
These distinctions are technical rather than commercially dispositive because the patent is expired. How strong was the patent estate?The patent appears to have had moderate historical value as a formulation patent but limited present value.
The absence of a process claim means the patent does not directly protect steroid synthesis, propylene-carbonate manufacture, mixing conditions or filling operations. Its principal barrier was the finished formulation. The breadth of claim 3 may also have presented validity pressure. The claim covers a large number of steroid substitutions, while claim 1 adds functional requirements concerning solubility, compatibility and therapeutic effectiveness. Potential historical validity issues would have included written description, enablement, indefiniteness and anticipation by earlier corticosteroid ointment disclosures. The patent’s age and expiration eliminate current enforcement consequences, regardless of how those issues might have been litigated. What patent litigation and settlements affect US 4,017,615?The patent cannot support a current US infringement action because its ordinary term expired in 1994. Any historical litigation or settlement involving the patent would no longer extend the patent’s statutory term. No current biosimilar litigation is relevant. The active ingredients described in claims 4 through 7 are small-molecule corticosteroids, not biologics. Biosimilar provisions under the Public Health Service Act do not apply.[4] A present commercial dispute involving one of these steroids would more likely concern:
A settlement agreement cannot revive an expired patent. It could, however, create private contractual restrictions among the parties if one existed, although such an agreement would not appear from the patent claims alone. Which companies are challenging or competing around this patent?The patent does not identify a current challenger because its term has ended. The commercial competitive landscape consists of manufacturers of topical corticosteroids, generic dermatology companies and suppliers of alternative ointment vehicles. The relevant competitive distinction is formulation architecture:
No biosimilar pathway applies. Generic competition is governed principally by the ANDA or applicable FDA pathway and by any later, still-active patents covering the relevant reference product. What generic launch risks exist today?US Patent 4,017,615 creates no current generic launch risk. A generic manufacturer could formulate and market a product that would historically have fallen within the claims, provided it satisfies all FDA, labeling, quality and other applicable requirements. Current risk should be assessed at the product level:
The expired patent may still be relevant as prior art against later patent applications. It could limit the ability of a later applicant to obtain broad claims covering the same propylene-carbonate ointment concept. What is the geographic coverage of US 4,017,615?The patent provides US rights only. It does not establish protection in Europe, Canada, Japan, Australia or other jurisdictions. Foreign counterparts would need separate identification through the patent family and national registers. Because the US patent expired decades ago, any surviving foreign patent would have to be assessed independently. Foreign patent terms, prosecution outcomes, supplementary protection certificates and national maintenance requirements may differ from the US position. Key Takeaways
FAQs About US Patent 4,017,615Does US Patent 4,017,615 still protect propylene carbonate ointments?No. The patent’s ordinary US term ended in 1994. It may remain relevant as prior art, but it does not create enforceable current patent rights. Can a generic use propylene carbonate in a corticosteroid ointment?Yes, US Patent 4,017,615 does not currently prevent that formulation. The generic must still satisfy FDA requirements and avoid any later unexpired patents. Does the patent cover fluocinolone acetonide products?Claim 5 appears directed to a difluorinated corticosteroid with 11β,21-dihydroxy and 16α,17-isopropylidene dioxy functionality. A commercial-name match should be confirmed against the original structural disclosure and product records. In any event, the claim is expired. Is US 4,017,615 an Orange Book patent?The patent is not a current Orange Book barrier. Orange Book status depends on NDA-submitted patent information for a specific approved product, and the patent’s 1994 expiration prevents current exclusivity. Can the expired patent block a later patent application?No, it cannot block issuance by itself, but it can be prior art. The patent could be cited against novelty, obviousness or written-description positions in a later application covering similar propylene-carbonate ointment technology. Sources:
More… ↓ |
Drugs Protected by US Patent 4,017,615
| Applicant | Tradename | Generic Name | Dosage | NDA | Approval Date | TE | Type | RLD | RS | Patent No. | Patent Expiration | Product | Substance | Delist Req. | Patented / Exclusive Use | Submissiondate |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| >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 4,017,615
| Country | Patent Number | Estimated Expiration | Supplementary Protection Certificate | SPC Country | SPC Expiration |
|---|---|---|---|---|---|
| Austria | 310948 | ⤷ Start Trial | |||
| Australia | 3322871 | ⤷ Start Trial | |||
| Belgium | 774489 | ⤷ Start Trial | |||
| Canada | 989306 | ⤷ Start Trial | |||
| Switzerland | 566783 | ⤷ Start Trial | |||
| >Country | >Patent Number | >Estimated Expiration | >Supplementary Protection Certificate | >SPC Country | >SPC Expiration |
