US Drug Patent 9,399,012: Claim Scope, Exclusivity, Orange Book Risk and Generic Entry Analysis

US Patent No. 9,399,012 protects selected intravenous acetaminophen dosing regimens, particularly a 600-700 mg dose, most specifically 650 mg, administered by 15-minute infusion approximately every four hours to adults or adolescents weighing at least 50 kg. The claims also reach formulation attributes associated with Ofirmev, including cysteine hydrochloride monohydrate, disodium phosphate dihydrate, mannitol, pH 5-6, osmolality of 200-400 mOsm/L, ready-to-use sterile solution, and storage at ambient temperature.

The strongest commercial claims are 29, 36-42, 48-78, and 79-109. The patent does not broadly cover all intravenous acetaminophen products. It focuses on a dosing-and-administration combination and, in narrower claims, a specific formulation and delivery profile.

What drug and product does US Patent 9,399,012 protect?

The patent is directed to intravenous acetaminophen for pain or fever, including postoperative pain, fever associated with infection, and patients who cannot receive oral medication.

The commercial product most closely associated with the claimed subject matter is Ofirmev, an intravenous acetaminophen product marketed by Mallinckrodt Hospital Products. Ofirmev is an acetaminophen injection supplied as a sterile 10 mg/mL solution and administered by intravenous infusion over 15 minutes. The FDA label provides a 650 mg dose every four hours or a 1,000 mg dose every six hours for adults and adolescents weighing at least 50 kg, subject to the daily acetaminophen maximum.[1]

Product characteristic	Patent claim profile	Ofirmev profile
Active ingredient	Acetaminophen	Acetaminophen
Route	Intravenous	Intravenous
Patient weight	At least 50 kg	At least 50 kg dosing category
Dose	About 550-800 mg; narrower claims 600-700 mg or 650 mg	650 mg or 1,000 mg
Frequency	Every 3-5 hours; narrower claims every four hours	650 mg every four hours
Infusion time	Five to 30 minutes; narrower claims 15 minutes	15 minutes
Daily exposure	Certain claims require less than 4 grams	FDA label limits total daily acetaminophen to 4 grams
Formulation	Cysteine, phosphate buffer, mannitol, pH and osmolality limitations	10 mg/mL sterile solution with excipients including mannitol and cysteine
Primary uses	Pain and fever	Pain and fever

How many independent inventions are represented by the claims?

The 109 claims form three principal claim groups.

Broad intravenous dosing claims: Claims 1-28 and 34-47

Claim 1 is the foundational method claim. It requires:

An adult or adolescent human weighing at least 50 kg.
A need for treatment of pain or fever.
Intravenous administration.
A pharmaceutical composition containing about 550-800 mg acetaminophen.
At least one repeat administration.
A repeat interval of approximately three to five hours.

Claims 2 and 3 add daily dose and frequency limitations. Claims 20-29 and 33-35 add disease, surgical, postoperative, pretreatment, or patient-condition limitations. Claims 41-46 address product presentation and administration mechanics.

These claims are method claims, not composition claims. A product manufacturer does not necessarily infringe merely by making or selling an intravenous acetaminophen solution. Direct infringement generally requires performance of the claimed treatment method. Liability risk can arise through induced infringement if labeling, promotional materials, order sets, or other instructions encourage the claimed regimen.

Narrow formulation and 650 mg regimen claims: Claims 29-40

Claim 29 is narrower and commercially significant. It requires a solution containing:

About 600-700 mg acetaminophen;
Cysteine hydrochloride monohydrate;
Disodium phosphate dihydrate;
Mannitol;
pH of about 5-6; and
Osmolality of about 200-400 mOsm/L.

The product must be administered intravenously and repeated after approximately three to five hours.

Claims 30 and 31 add acetaminophen concentration, with claim 31 specifying approximately 1% w/v. At 1% w/v, a 650 mg dose corresponds to approximately 65 mL of solution.

Claims 36-40 focus on 650 mg dosing and a four-hour interval. These claims are especially relevant to products labeled for the same regimen as Ofirmev.

15-minute infusion and sub-4-gram claims: Claims 48-78 and 79-109

Claims 48 and 79 are separate independent method claims directed to pain and fever, respectively. They require:

A subject weighing at least 50 kg;
600-700 mg acetaminophen;
Repeat dosing at least approximately every four hours;
15-minute intravenous infusion; and
Less than 4 grams over 24 hours.

Claims 49 and 80 narrow the dose to 650 mg. Claims 78 and 109 specify 650 mg every four hours over a 24-hour period. Claims 53-58 and 84-89 address ready-to-use presentation, lyophilized powder, and two-year ambient-temperature storage. Claims 59-77 and 90-108 add formulation excipients, pH, antioxidant concentration, isotonicity agents, and osmolality.

Which claims have the greatest infringement exposure?

Claims 48 and 79 create the clearest infringement framework because they combine dose, frequency, infusion duration, patient weight, and daily exposure. Claims 49 and 80 are particularly important for a 650 mg product.

A competing product would face the highest literal-infringement risk if its label or clinical instructions specify all of the following:

650 mg intravenous acetaminophen;
Adult or adolescent patients weighing at least 50 kg;
Administration every four hours;
A 15-minute infusion;
Less than 4 grams in 24 hours; and
Treatment of pain or fever.

A product administered at 1,000 mg every six hours would generally fall outside the literal scope of claims requiring 600-700 mg or a three-to-five-hour interval. A product administered every six hours at 650 mg would also avoid the principal every-four-hour claims, although broader claims must be reviewed independently.

Competitor design choice	Likely effect on literal claim risk
1,000 mg every six hours	Reduces risk under 600-700 mg and 650 mg claims
650 mg every six hours	Avoids every-four-hour claims but may implicate broader interval claims only if within the claimed range
650 mg every four hours	Highest risk under claims 36-40, 48-50 and 78
Infusion over 30 minutes	May avoid claims requiring a 15-minute infusion, but not claims covering five to 30 minutes
pH outside 5-6	May avoid narrow formulation claims, but not broad dosing claims
No cysteine	May avoid claim 29 and its dependents, but not claims requiring only acetaminophen
No mannitol	May avoid mannitol-specific claims, subject to broader excipient claims
Daily dose of exactly 4 grams	May avoid “less than 4 grams” claims, but could remain within other claims
Oral or intramuscular route	Avoids the intravenous-route limitation

What formulation characteristics are protected?

The patent has layered formulation protection rather than one uniform composition claim.

Antioxidants

Claims 4-6, 67-72, 98-103 cover antioxidants, with cysteine hydrochloride monohydrate as the principal narrow species. The claims also identify thiol-containing compounds, glutathione, dithiothreitol, ascorbic acid and derivatives, and polyhydroxylated compounds.

Mannitol appears in both antioxidant and isotonicity claim groupings. This creates drafting breadth but also raises claim-construction and enablement questions because mannitol's principal formulation function is ordinarily isotonicity rather than antioxidant activity.

Buffer system

The claims identify disodium phosphate dihydrate and broader classes of phosphate, citrate, acetate, lactate, succinate and other pharmaceutically acceptable buffering systems. Claims 59-61 and 90-92 specify buffer concentration ranges from 0.05% to 2.0%, with narrower ranges of 0.1-0.7% and 0.2-0.3%.

Isotonicity agents

Claims 13-15 and 73-76 cover dextrose, mannitol, lactose, sorbitol, glycerol, sucrose, salts, polyethylene glycols and related agents. Mannitol is the principal species identified in the patent's narrow formulation claims.

pH and osmolality

The broad pH range is 4-8. The commercially important narrower range is pH 5-6. Osmolality is limited to 200-400 mOsm/L.

These parameters can be effective prosecution and design-around variables. A formulation outside the pH or osmolality range may avoid a narrow claim while retaining the same active ingredient and route of administration.

Are the claims internally consistent?

Several claim dependencies create potential construction issues.

Claim 12 refers to "the pharmaceutical composition of claim 11," although claim 11 is a method claim. The same drafting problem appears in other portions of the claim set where composition limitations are attached to method claims.

Claims 48 and 79 require less than 4 grams of acetaminophen over 24 hours. Claims 50-52 and 81-83 require at least six, seven, or eight administrations in 24 hours while inheriting the 600-700 mg dose limitation.

At the minimum inherited dose:

Six doses of 600 mg equal 3,600 mg.
Seven doses of 600 mg equal 4,200 mg.
Eight doses of 600 mg equal 4,800 mg.

At 650 mg:

Six doses equal 3,900 mg.
Seven doses equal 4,550 mg.
Eight doses equal 5,200 mg.

Accordingly, claims requiring seven or eight doses appear facially inconsistent with the inherited requirement of less than 4 grams per 24 hours. Those claims may present written-description, indefiniteness, claim-construction, or enforceability issues depending on prosecution history and judicial interpretation. Claim 78, which specifies six 650 mg doses every four hours, is mathematically consistent with a less-than-4-gram limitation because six doses total 3.9 grams.

When does US Patent 9,399,012 lose exclusivity?

The patent's expiration date cannot be derived from the claim text alone. The controlling date depends on the earliest effective nonprovisional priority filing, patent-term adjustment, terminal disclaimers, and any applicable patent-term extension.

The statutory framework is generally 20 years from the earliest effective nonprovisional filing date under 35 U.S.C. § 154.[2] The patent's term should therefore be evaluated from the USPTO continuity data and the patent-specific term calculation, not from the issue date of July 26, 2016.

The FDA Orange Book, when the patent is listed against an approved acetaminophen injection product, is the relevant regulatory source for the listed expiration date and any use-code information.[3] An Orange Book listing does not itself establish validity or infringement. It affects ANDA certification and the timing of potential approval.

What is the Orange Book and Paragraph IV significance?

A generic applicant seeking approval of an intravenous acetaminophen product through an ANDA must address listed patents for the reference product. The applicant may certify that:

The patent information was not submitted;
The patent has expired;
The generic will not be marketed until patent expiration; or
The patent is invalid, unenforceable, or will not be infringed.

The fourth option is a Paragraph IV certification under the Hatch-Waxman Act.[4]

For US Patent 9,399,012, a Paragraph IV dispute would likely focus on:

Whether the proposed label induces the patented dosing regimen;
Whether the proposed product meets the 600-700 mg or 650 mg dose range;
Whether the label specifies a four-hour interval;
Whether the product is administered over 15 minutes;
Whether the formulation contains cysteine, disodium phosphate and mannitol;
Whether the product has the claimed pH and osmolality; and
Whether the claimed regimen is obvious in view of known acetaminophen dosing, IV delivery, and postoperative analgesia practices.

A generic applicant can reduce risk through a label that omits the patented regimen if the FDA permits a carve-out and the remaining labeling supports approval. A label that reproduces the reference product's 650 mg every-four-hour dosing instructions creates greater induced-infringement exposure.

Which companies are relevant to the patent landscape?

Mallinckrodt and Ofirmev

Mallinckrodt acquired Cadence Pharmaceuticals in 2014 in a transaction valued at approximately $1.3 billion.[5] The acquisition transferred Ofirmev and the associated commercial and intellectual-property position to Mallinckrodt.

Generic intravenous acetaminophen manufacturers

Potential challengers include companies with sterile injectable manufacturing capacity and ANDA portfolios in hospital products. The most relevant competitive group includes large generic injectable manufacturers and specialty pharmaceutical companies with experience in parenteral products.

The commercial barrier is higher than for an ordinary oral acetaminophen tablet because a generic entrant must establish sterile manufacturing, container-closure integrity, stability, particulate control, extractables and leachables, and validated intravenous administration characteristics. Patent clearance is only one part of the entry analysis.

Biosimilar risk

Biosimilar risk is not applicable. Acetaminophen is a chemically synthesized small molecule, not a biologic. Competitive entry would proceed through the ANDA pathway or, in some circumstances, a 505(b)(2) application rather than the biosimilar pathway under the Public Health Service Act.

What patent families should be reviewed alongside US 9,399,012?

A complete freedom-to-operate review should separate the estate into four categories:

Estate category	Relevant subject matter	Commercial issue
Formulation patents	Acetaminophen solution, antioxidant, buffer, isotonicity and stability	May block composition manufacture or sale
Dosing patents	650 mg, four-hour interval, less-than-4-gram daily dosing	May block label-directed use
Administration patents	15-minute infusion, dilution, ready-to-use presentation	May affect label and hospital protocols
Manufacturing patents	Sterile filling, stability, container systems and lyophilization	May create process or supply-chain barriers

Earlier Ofirmev-related patents and continuations should be checked for overlapping formulation or administration claims. The relevant analysis must include patent-family members, continuations, divisionals, reissues, terminal disclaimers, assignments, maintenance-fee status, and Orange Book listings.

How strong is the patent estate?

The estate is strongest against a product that copies the reference product's labeled 650 mg every-four-hour regimen and 15-minute infusion. It is weaker against alternative dose schedules, alternative infusion durations, and formulations that omit one or more named excipients or fall outside the pH and osmolality ranges.

Risk factor	Assessment
Dose-specific protection	Strong against 650 mg labeling
Frequency protection	Strong against every-four-hour labeling
Infusion protection	Stronger for 15-minute administration than for broader five-to-30-minute claims
Formulation protection	Moderate to strong where cysteine, phosphate and mannitol are all present
Design-around potential	Meaningful through dose, frequency, excipient and infusion changes
Method-of-use enforcement	Dependent on label content and evidence of encouraged use
Claim clarity	Reduced by inconsistent dependencies and mathematically conflicting dose-frequency claims
Manufacturing barrier	Significant because sterile injectable production is technically demanding

What generic launch scenarios exist?

Launch after patent expiry

This is the lowest litigation-risk pathway. The applicant may align its label with the reference product after the relevant listed patents expire.

Paragraph IV launch

A challenger may argue that the claims are invalid, unenforceable or not infringed. The main invalidity arguments would likely address obviousness, written description, enablement and indefiniteness. The strongest noninfringement arguments would focus on a different dose, interval, infusion duration, formulation or label.

Skinny-label launch

A generic may seek approval without instructions for the patented 650 mg every-four-hour regimen if the FDA permits removal of the protected use. The practical value of a carve-out depends on whether hospitals and prescribers can use the generic for nonprotected indications without relying on the omitted instructions.

505(b)(2) entry

A 505(b)(2) applicant could pursue a product with a modified formulation, presentation or dosing approach. This pathway may create separate patent-certification obligations and does not automatically avoid method or formulation claims.

Key Takeaways

US Patent 9,399,012 is primarily a method patent covering intravenous acetaminophen dosing, not a blanket monopoly over all IV acetaminophen.
The most important commercial embodiment is 650 mg administered by 15-minute IV infusion every four hours to patients weighing at least 50 kg.
Claims 29 and 36-40 add formulation and 650 mg regimen limitations closely aligned with Ofirmev.
Claims 48-78 and 79-109 combine a 15-minute infusion with a less-than-4-gram daily exposure.
A 1,000 mg every-six-hour product presents a meaningful design-around relative to the central 650 mg every-four-hour claims.
Formulation design-arounds may target cysteine, phosphate, mannitol, pH and osmolality.
The claims contain apparent dependency and arithmetic inconsistencies, particularly for seven- and eight-dose claims.
Acetaminophen has no biosimilar pathway risk because it is a small-molecule drug.
Generic entry risk depends on Orange Book listings, patent-family continuity, claim-term calculations, Paragraph IV certifications and the proposed ANDA label.
Sterile injectable manufacturing and hospital distribution remain material non-patent barriers to entry.

FAQs About US Patent 9,399,012

Does US Patent 9,399,012 cover oral acetaminophen?

No. The independent claims require intravenous administration. Oral acetaminophen products fall outside the literal scope of these claims.

Does a 1,000 mg every-six-hour regimen infringe the patent?

It is less likely to infringe claims limited to 600-700 mg, 650 mg or a three-to-five-hour interval. The complete claim set and any doctrine-of-equivalents theory would still require separate review.

Can a generic use the same acetaminophen formulation with a different label?

Potentially. A different label may reduce induced-infringement risk, but it does not eliminate risk under composition, formulation, manufacturing or broader method claims.

Does a pH of 6.5 avoid the patent?

It may avoid claims limited to pH 5-6, but not claims with the broader pH 4-8 range. The product must be mapped against each asserted claim.

Why is a 650 mg four-hour regimen commercially important?

Six 650 mg doses total 3,900 mg in 24 hours, which fits the patent's less-than-4-gram limitation while matching the labeled dosing architecture for intravenous acetaminophen in patients weighing at least 50 kg.

References

U.S. Food and Drug Administration. (2023). Ofirmev (acetaminophen injection) prescribing information.
United States Code, 35 U.S.C. § 154.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book.
United States Code, 21 U.S.C. § 355(j).
Mallinckrodt plc. (2014). Mallinckrodt completes acquisition of Cadence Pharmaceuticals.
United States Patent and Trademark Office. (2016). U.S. Patent No. 9,399,012, methods for treating pain or fever using intravenous acetaminophen.

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Mallinckrodt Hosp	OFIRMEV	acetaminophen	SOLUTION;INTRAVENOUS	022450-001	Nov 2, 2010		DISCN	Yes	No	9,399,012*PED	⤷ Start Trial			Y		⤷ Start Trial
>Applicant	>Tradename	>Generic Name	>Dosage	>NDA	>Approval Date	>TE	>Type	>RLD	>RS	>Patent No.	>Patent Expiration	>Product	>Substance	>Delist Req.	>Patented / Exclusive Use	>Submissiondate

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Canada	2705733	⤷ Start Trial
Japan	2011503198	⤷ Start Trial
Japan	5909750	⤷ Start Trial
World Intellectual Property Organization (WIPO)	2009064928	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 9,399,012

Which drugs does patent 9,399,012 protect, and when does it expire?

Summary for Patent: 9,399,012