Details for Patent: 4,140,756

Summary for Patent: 4,140,756

Title:	Film-coated matrix core tablet
Abstract:	A tablet for controlled release of a water soluble medicament or dietary supplement is comprised of a water insoluble wax-like matrix core containing the water soluble medicament and coated with a permeable erosion resistant polymeric film. The core constitutes 95% or more of the tablet weight.
Inventor(s):	Claude E. Gallian
Assignee:	Mead Johnson and Co LLC
Application Number:	US05/843,196
Patent Claim Types: see list of patent claims	Use; Composition; Formulation; Dosage form;

Executive summary
U.S. Drug Patent 4,140,756 covers a continuous-release oral tablet for water-soluble salts (potassium chloride or sodium chloride) in which a high drug-load compressed core (core ≥95 wt% of tablet; core contains 72–85 wt% water-soluble medicament and 13–25 wt% wax-like insoluble material such as stearic acid) is overlaid by a permeable, erosion-resistant polymeric film (film ≤5 wt%; polymer blend hydroxypropyl methyl cellulose (HPMC) + ethyl cellulose (EC) plasticized (e.g., glycerol) and tuned to maintain integrity across 5–8 hours). Claim scope is tightly constrained by both composition percentages and a rolling-bottle dissolution profile (early-hour kinetics, deviation limits, and high end-of-period release). The patent’s U.S. exclusivity period has long expired; practical remaining value today is mostly as prior art and for assessing freedom-to-operate (FTO) for similar salt ER (extended-release) tablets.

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What is US Patent 4,140,756 and what does it claim about continuous-release KCl or NaCl tablets?

Core claim concept (Claim 1)
The patent claims a specific ER tablet architecture and quantitative dissolution performance:

1. Drug and dose range

   • Water-soluble medicament: ≥0.75 g in the tablet core (Claim 1).
   • Dependent claims limit medicament to:
     • Potassium chloride (Claim 2, and the detailed potassium embodiments in Claims 12 and 16)
     • Sodium chloride (Claim 3)

2. Core composition and proportions

   • Tablet comprises:
     • Core constituting ≥95% of tablet weight
   • Core contains:
     • 72–85 wt% water-soluble medicament
     • 13–25 wt% water-insoluble wax-like material (explicitly stearic acid in Claim 4)

3. Film form and content

   • Continuous permeable erosion-resistant polymeric film
   • Film constitutes up to 5 wt% of tablet weight
   • Film is a polymer major / plasticizer minor system

4. Polymer/plasticizer selection

   • Polymer and plasticizer quantities are selected so film:
     • remains intact for at least a portion of the 5–8 hour dissolution period
     • confers an ER dissolution profile by the rolling bottle method.

5. Dissolution profile constraints (hard boundaries)
   The dissolution profile is defined by multiple numerical criteria:

   • 45–75% dissolved during the first 3 hours
   • max 25% dissolved during the first hour
   • ≥66% dissolved during the first 5 hours
   • ≥90% dissolved during the entire 8-hour dissolution period
   • Early-rate uniformity:
     • First-hour deviation from average hourly amount during first 3 hours is ≤22%
   • Film effect:
     • Dissolution from core without film in first hour exceeds the average hourly amount during first 3 hours by >22%
     • This creates a measurable “film impact” requirement.

Dependent claim coverage (Claims 2–19)
The dependents add narrower embodiments:

• Drug identity: KCl (Claim 2) and NaCl (Claim 3)
• Wax-like insoluble material: stearic acid (Claim 4)
• Tablet weight split:
  • Core approx 97%, film approx 3% (Claim 5)
• Polymer blend: HPMC + EC (Claim 6)
• Plasticizer example: glycerol (Claim 7)
• Film formulation ratios:
  • 9 parts polymer : 1 part plasticizer (Claim 8)
  • 5 parts HPMC : 4 parts EC : 1 part glycerol (Claim 9)
• Decorative/finish coat:
  • Film enclosed within a readily erodible decorative finish coat that does not materially affect dissolution profile (Claims 10 and 13)
  • Decorative coat includes HPMC with opacifiers (Claims 14 and 18)
  • Decorative coat includes HPMC containing silicon dioxide at approximate equal weight (Claims 15 and 19)

Potassium-specific “example builds”
Claims 12 and 16 specify concrete core amounts and film composition:

• Claim 12:

  • Core: 937.5 mg KCl + 187.5 mg stearic acid + 20–100 mg excipients/lubricants/binders/colors
  • Film: up to 5% tablet weight, comprising 5 parts HPMC : 4 parts EC : 1 part glycerol
  • Dissolution performance matches Claim 1 kinetic constraints for KCl ER

• Claim 16:

  • Core: 750 mg KCl + 150 mg stearic acid + 16–80 mg excipients
  • Film: about 3.6% tablet weight
  • Film composition fixed to 5:4:1 (HPMC:EC:glycerol)
  • Dissolution performance constraints (KCl) match the Claim 1 profile

What this means for infringement analysis
The claim set is best read as a tight ER-KCl/NaCl tablet engineering window:

• You must match the core drug:wax ratio (72–85% drug, 13–25% stearic acid) and
• match a continuous permeable film content (≤5 wt%) and composition (polymer major blend with a specific plasticizer system),
• and pass the rolling-bottle dissolution test constraints, including the film-vs-no-film first-hour kinetic separation.

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How do the dissolution “rolling bottle method” limitations define claim scope in US 4,140,756?

The claims embed both performance and causation
The dissolution limitations do more than set endpoints. They also require:

• ER suppression early:
  • ≤25% in first hour
• Sustained release:
  • ≥66% by 5 hours
• Near completion by 8 hours:
  • ≥90% by 8 hours
• Tight early-hour consistency:
  • First-hour dissolved amount must deviate by no more than 22% from the mean hourly amount dissolved during the first 3 hours
• Demonstrated necessity of the film:
  • If you remove the film, first-hour dissolution must exceed the first-3-hour average by >22%

Practical reading
A formulation can be “close” compositionally but non-infringing if it fails one of the kinetic gates. Conversely, formulations with composition outside some ranges still risk infringement if they achieve the claimed dissolution profile under the specified rolling bottle method, but the claim also ties film composition and core ratios to that performance.

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Which film compositions in the patent are likely to matter most for FTO around KCl ER tablets?

Film composition anchors
Key claim-level constraints:

• Film content: up to 5% of tablet weight (Claim 1)
• Polymer major / plasticizer minor:
  • Dependent examples specify HPMC + EC (Claims 6 and 9)
  • Plasticizer: glycerol (Claims 7 and 9)
• Film ratio examples:
  • 9 parts polymer : 1 part plasticizer (Claim 8)
  • 5:4:1 HPMC:EC:glycerol (Claim 9)
• Film integrity duration: must remain intact “for at least a portion” of the 5–8 hour dissolution period and deliver the kinetic profile

Decorative finish coat is secondary but still claimed

• Claims 10 and 13–19 extend structure to include an enclosing decorative finish coat that erodes during dissolution without materially affecting the dissolution profile.

Design-around pressure points
In practice, the most straightforward FTO pressure points are:

• film total wt% (≤5% gate),
• core stearic acid wt% (13–25% gate),
• core drug wt% (72–85% gate),
• and rolling bottle dissolution performance.

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What patent estate does US 4,140,756 imply for KCl continuous release, and what does that mean after expiration?

Single patent vs. family
The user-provided material is only the claims of U.S. 4,140,756. Without the prosecution history, related patents, and bibliographic data (assignee, filing dates, priority, continuations), a complete landscape cannot be reconstructed from the prompt alone.

However, the claim scope indicates a likely cluster
Claim structure is typical of an ER “technology patent” with:

• core composition ranges
• a tuned polymeric film (permeable, erosion resistant, plasticized)
• and explicit dissolution test requirements

That kind of claim suite often appears alongside continuations or related patents covering alternative polymers, film ratios, drug loads, or alternative dissolution equivalence metrics. But those cannot be enumerated from the supplied text.

Expiration impact
U.S. Drug Patent 4,140,756 is from an era when ER technology patents are generally non-current for regulatory exclusivity. Today, any relevance is most commonly:

• prior art for validity and obviousness in later filings
• a historical baseline for ER KCl/NaCl tablet designs using HPMC/EC and stearic acid-wax blends.

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What is the risk profile for generic or “follow-on” ER KCl tablets relative to US 4,140,756?

Active risk is primarily about infringement theory, not regulatory exclusivity
Because the patent is old and ER KCl products are widely commercialized, the operational question is usually:

• whether a newer tablet concept overlaps substantially identical claim elements, particularly the composition gates and rolling bottle dissolution profile.

High-infringement-likelihood overlap indicators

• core has drug at 72–85 wt% and stearic acid at 13–25 wt%
• tablet has an HPMC/EC glycerol permeable film at ≤5 wt%
• dissolution under rolling bottle method matches:
  • first-hour ≤25%
  • ≥66% at 5 hours
  • ≥90% at 8 hours
  • deviation and no-film separation thresholds

Lower-likelihood overlap indicators

• different wax-like material or wax absence
• film content materially above 5 wt%
• polymer system not within the claimed polymer/plasticizer selection (at least as constrained in dependent claims)
• dissolution profile materially different from the chained numerical constraints

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How do the dependent claims narrow coverage to specific “product-like” embodiments?

Claim 12 and 16 are especially product-shaped
They lock in:

• exact KCl and stearic acid amounts (within a narrow practical range given the excipient band)
• a fixed film ratio (5:4:1 HPMC:EC:glycerol)
• fixed or approximate film weight (up to 5% vs about 3.6%)

These dependent claims create strong “anchor embodiments” for infringement mapping against tablet master formulation sheets, even when the independent claim is broad.

Decorative coat claims add a second structural layer
If a competitor uses a finish coat, it may still avoid the specific dependent claim if the coat is not “readily erodible” or if it materially affects the dissolution profile. But the finish coat is still framed as not materially affecting the dissolution constraints.

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What other patents could plausibly intersect with US 4,140,756 based on its claim mechanics?

From the claim text alone, the most plausible intersection themes are:

• ER matrices for high drug load salt formulations using wax-like insoluble materials (stearic acid class)
• polymeric permeable/erosion-resistant coatings using cellulose ethers (HPMC) and ethyl cellulose
• plasticized film systems with glycerol-like plasticizers
• formulation-dependent dissolution profiles expressed in standard apparatus metrics

A complete “how many patents cover this” or “who is challenging whom” landscape cannot be produced from the provided prompt because it requires patent family data, assignee, priority chain, and claim citations.

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Key Takeaways

• US 4,140,756 claims a continuous-release oral ER tablet built from a high drug-load compressed core with 72–85 wt% water-soluble medicament and 13–25 wt% wax-like insoluble material (stearic acid), coated with a continuous permeable erosion-resistant film of ≤5 wt%.
• The polymer film is tuned using polymer major + plasticizer minor. Dependent claim examples strongly suggest HPMC + EC with glycerol in 5:4:1 ratios.
• The claim scope is constrained by a rolling bottle dissolution profile that tightly controls first-hour burst, 5-hour release, 8-hour completion, and film-vs-no-film separation.
• The potassium-specific dependent claims (notably Claims 12 and 16) are product-shaped with defined KCl and stearic acid loads and fixed film composition, making them the most direct infringement hooks if a competitor’s formulation matches the same quantitative build.
• Today, exclusivity is not the dominant lens; the main use of this patent is historical validity/prior-art positioning and FTO screen for formulations engineered to reproduce the same dissolution kinetics and compositional gates.

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FAQs

1) Does US 4,140,756 protect both potassium chloride and sodium chloride tablets?
Yes. Claim 1 covers “water soluble medicament” and dependent claims specify potassium chloride (Claim 2) and sodium chloride (Claim 3).

2) What dissolution conditions must an accused tablet meet to fall within Claim 1?
Under the rolling bottle method, it must meet the chained numeric gates: 45–75% by 3 hours, ≤25% in the first hour, ≥66% by 5 hours, ≥90% by 8 hours, plus the ≤22% deviation condition and the no-film vs with-film separation condition.

3) Is stearic acid required for protection under the claims?
Claim 1 allows a “wax-like” water-insoluble material range, while dependent Claim 4 specifies stearic acid. Stearic acid is not strictly required by Claim 1 as written, but it is explicitly claimed in dependent scope.

4) How important is the polymer/plasticizer ratio in US 4,140,756?
It is central because the film must remain intact and produce the claimed rolling-bottle dissolution profile. Dependent claims lock example ratios, including 5:4:1 HPMC:EC:glycerol and 9:1 polymer:plasticizer.

5) Do decorative finish coats change infringement risk?
Yes for dependent claims. Claims 10 and 13–19 add a finish coat that erodes during dissolution without materially affecting the dissolution profile. Designs with finish coats that alter dissolution kinetics could fall outside those dependent embodiments.

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References (APA)

1. U.S. Patent No. 4,140,756.

Drugs Protected by US Patent 4,140,756

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