United States Patent 6,132,758 (Loratadine + Aminopolycarboxylic Acid Syrup): Claim Scope and Patent Landscape

What does US 6,132,758 claim cover?

US 6,132,758 is directed to liquid oral antihistaminic formulations built around loratadine plus an aminopolycarboxylic acid (or salt) at defined concentration ranges. The claims fall into two functional buckets:

1) Formulation composition for stability and degradation control

Core: loratadine syrup + aminopolycarboxylic acid (0.05 to 5 mg/mL) [Claims 1, 13].
Specific aminopolycarboxylic acids and salts: iminodiacetic acid; methyliminodiacetic acid; nitrilotriacetic acid; EDTA (ethylenediaminetetraacetic acid); diethylenetriaminepentaacetic acid; 1,2-diaminocyclohexane-tetraacetic acid; N-hydroxyethylenediaminetriacetic acid; plus combinations [Claim 2].
EDTA-specific embodiments [Claims 3, 15, 16].
Concentration subsets (0.1 to 1 mg/mL; and 0.25 to 0.5 mg/mL) [Claims 4, 5].
A stability function: aminopolycarboxylic acid present at an amount sufficient to inhibit loratadine degradation [Claims 14, 16].

2) Storage-stable loratadine syrup defined by impurity/hydroxymethyl limits

Storage-stable loratadine syrup with:
- <0.49% by weight of 2-hydroxymethyl loratadine [Claim 11]
- <0.53% by weight of 4-hydroxymethyl loratadine [Claim 12]

A third bucket adds optional co-therapeutic agents:

Combination syrups where loratadine/aminopolycarboxylic acid is further formulated with a decongestant, analgesic, antitussive, expectorant, or combinations [Claim 6].
Decongestant examples explicitly recited: pseudoephedrine and phenylpropanolamine [Claims 7, 8].
Analgesic combinations are also claimed, but the analgesic identity is not limited in the excerpt [Claims 9, 10].

What is the claim-by-claim scope in practical terms?

Independent claim coverage

Claim 1 (anchor scope)

Requires:
- “An antihistaminic syrup” (liquid oral formulation)
- loratadine
- about 0.05 to about 5 mg/mL aminopolycarboxylic acid (or salt)
Claim breadth:
- High because it is not limited to a single aminopolycarboxylic acid; it covers any aminopolycarboxylic acid (or salt) that falls within the recited functional and concentration framing.

Claim 13 (composition restatement)

“An antihistaminic syrup comprising loratadine and an aminopolycarboxylic acid.”
This is broader conceptually (it does not restate the numeric range in the excerpt) but is likely constrained in practice by dependence or specification tie-ins.

Claim 11 and Claim 12 (storage stability via impurity thresholds)

These are “product-by-result” style elements:
- Must meet impurity limits for specific hydroxymethyl degradation products.

Dependent claims: how much do they narrow?

Claim 2 narrows aminopolycarboxylic acids to a specified list (and combinations of two or more).

Limits the “aminopolycarboxylic acid” universe to named chemistries within that list.

Claim 3 narrows to EDTA.

Claims 4 and 5 impose concentration windows:

0.1 to 1 mg/mL [Claim 4]
0.25 to 0.5 mg/mL [Claim 5]

Claims 14 and 16 add functional limitation:

Aminopolycarboxylic acid amount is “sufficient to inhibit degradation of said loratadine.”
Practically, this is a performance threshold that can be evaluated by accelerated stability testing showing reduced degradation relative to a control.

Claim 6 adds co-actives:

Decongestant, analgesic, antitussive, expectorant, or any combination.
This creates additional infringement exposure for combo-syrup products.

Claims 7 and 8 specify decongestants:

pseudoephedrine and phenylpropanolamine [Claim 7]
pseudoephedrine (in particular) [Claim 8]

Claims 9 and 10 reference analgesics:

They expand combo-syrup permutations but still depend on the loratadine + aminopolycarboxylic acid base.

What is the enforceable “moving parts” map?

For freedom-to-operate and design-around, the claims hinge on four technical axes:

1) Dosage form

“Syrup” implies oral liquid. If a product is not a syrup (e.g., tablet, capsule, oral suspension not characterized as “syrup”), claim fit may change, but the excerpt does not define “syrup.”

2) API

Must include loratadine (not a prodrug, not another antihistamine).

3) Stabilizer identity

aminopolycarboxylic acid and salts:
- Broad in Claim 1 (as presented)
- Narrowed list in Claim 2 dependent claim

4) Stabilizer exposure

Numeric range in Claim 1: ~0.05 to ~5 mg/mL
Additional ranges for dependent claims: 0.1 to 1 mg/mL and 0.25 to 0.5 mg/mL
Plus performance sufficiency: “inhibit degradation.”

And for the separate “impurity limit” claims:

Meeting threshold mass fractions for:
- 2-hydroxymethyl loratadine (<0.49% w/w)
- 4-hydroxymethyl loratadine (<0.53% w/w)

How do the impurity-limit claims interact with the aminopolycarboxylic acid claims?

The patent has two overlapping stability strategies:

Reagent-based stability: aminopolycarboxylic acid added at specified amounts to inhibit degradation [Claims 1, 14, 16].
Outcome-based stability: final formulation must have low levels of specific hydroxymethyl impurities [Claims 11, 12].

In infringement analysis, a product with EDTA at the relevant concentration can satisfy the first strategy; a product can also satisfy the second strategy if it meets the impurity limits even if it uses a different stabilization mechanism, depending on how claim interpretation ties the impurity limits to the composition.

What is the likely claim landscape around this patent?

Within the constraints of the claim text provided, US 6,132,758 occupies a specific formulation niche:

Loratadine in syrup form
Stabilization against hydroxymethyl degradation products (as evidenced by Claims 11 and 12)
Stabilizer class limited to aminopolycarboxylic acids (especially EDTA)

This means the practical competitive and legal landscape tends to cluster around:

Different preservatives/stabilizers for loratadine syrups (including non-aminopolycarboxylate approaches)
EDTA level optimization
Impurity-controlled formulations engineered to keep hydroxymethyl loratadine below stated thresholds
Combination cold products that add pseudoephedrine or other actives

Scope gaps and design-around pressure points

Based on the claim language in the excerpt, the strongest pressure points for product design are:

1) Aminopolycarboxylic acid concentration window (Claim 1 and dependent ranges)

Claim 1 requires aminopolycarboxylic acid at about 0.05 to about 5 mg/mL. If a formulation uses an aminopolycarboxylic acid but falls materially outside this window, it can avoid Claim 1 scope as written. Dependent claims further narrow EDTA embodiments and tighter windows [Claims 3-5, 15-16].

2) Aminopolycarboxylic acid identity (Claim 2 dependent narrowing)

If a competitor uses a stabilization agent that is not among the listed aminopolycarboxylic acids, it can avoid Claim 2-dependent scope. Claim 1 as provided is broader, but Claim 2’s list still functions as a key claim corridor.

3) Degradation “sufficiency” (functional limitation in Claims 14 and 16)

Even with EDTA present, competitors may try to keep the amount below what stability testing shows as “sufficient to inhibit degradation,” but that is a performance-based litigation variable.

4) Impurity thresholds (Claims 11 and 12)

Even if a competitor avoids aminopolycarboxylic acid entirely or uses different concentrations, it can still face exposure if its loratadine syrup product meets the impurity thresholds by coincidence or by alternate stabilization pathways. These claims can therefore be used as leverage in enforcement focused on test results.

Claim scope table (quick infringement mapping)

Claim	Core limitation(s)	Key numbers / lists in excerpt	Practical risk trigger
1	Antihistaminic syrup with loratadine + aminopolycarboxylic acid	aminopolycarboxylic acid ~0.05 to ~5 mg/mL	Any syrup with loratadine plus aminopolycarboxylic acid in range
2	Aminopolycarboxylic acid identity	list includes EDTA, NTA, etc.	Using one of the listed acids in Claim 1 formulation
3	EDTA-specific	EDTA is aminopolycarboxylic acid	EDTA-enabled stability formulations
4	Concentration subset	~0.1 to ~1 mg/mL	Formulations landing in mid-range exposure
5	Concentration subset	~0.25 to ~0.5 mg/mL	Narrow sub-range; easier to target in development
6	Combo syrup expansion	decongestant/analgesic/antitussive/expectorant allowed	Cold/flu combo syrups built on Claim 1 base
7	Decongestant list	pseudoephedrine, phenylpropanolamine	“Loratadine + pseudoephedrine/phenylpropanolamine” combos
8	pseudoephedrine specifically	pseudoephedrine included	Commonly used decongestant direction
9	Analgesic added	unspecified “an analgesic”	Combo products with pain relievers
10	pseudoephedrine claim + analgesic	depends on Claim 8	Multi-active cold product architectures
11	Storage-stable syrup by impurity	<0.49% w/w 2-hydroxymethyl loratadine	Test result compliance can define infringement
12	Storage-stable syrup by impurity	<0.53% w/w 4-hydroxymethyl loratadine	Test result compliance can define infringement
13	Broad base formulation	loratadine + aminopolycarboxylic acid	Base composition category
14	Functional sufficiency	amount sufficient to inhibit degradation	Stability-driven infringement pathway
15	EDTA + base	EDTA present	EDTA-containing products
16	EDTA + functional sufficiency	EDTA amount sufficient to inhibit degradation	EDTA at stability-effective level

Business-relevant landscape conclusions

1) This patent is a formulation stability patent with two enforcement levers: reagent composition (loratadine + aminopolycarboxylic acid at defined exposure) and product quality (low hydroxymethyl impurities). 2) EDTA is a central commercial target because multiple dependent claims explicitly recite EDTA, plus concentration and degradation-inhibition performance language. 3) Combo products widen exposure: pseudoephedrine-based and multi-active syrups can fall within dependent claims if the aminopolycarboxylic acid base is present. 4) Analytical test results matter: hydroxymethyl impurity thresholds are direct claim elements, so quality/COA testing and accelerated stability data can become infringement evidence independent of formulation strategy.

Key Takeaways

US 6,132,758 claims loratadine syrup stabilized with aminopolycarboxylic acid at ~0.05 to ~5 mg/mL (Claim 1) and tighter windows for dependent claims.
The patent’s strongest specificity is EDTA (Claims 3, 15, 16) plus concentration subsets (Claims 4, 5).
A second enforcement track uses impurity limits: <0.49% 2-hydroxymethyl loratadine and <0.53% 4-hydroxymethyl loratadine (Claims 11, 12).
Combo-syrup architecture is explicitly contemplated through dependent claims allowing pseudoephedrine and other added therapeutics (Claims 6-10).

FAQs

1) Does the patent require EDTA to infringe?

No. Claim 1 requires an aminopolycarboxylic acid in the defined concentration range; EDTA is singled out in dependent claims (Claims 3, 15, 16).

2) What is the minimum aminopolycarboxylic acid concentration stated?

The excerpted Claim 1 range is about 0.05 mg/mL to about 5 mg/mL.

3) Can a product avoid the aminopolycarboxylic acid claims but still face risk under impurity-limit claims?

Yes. Claims 11 and 12 are keyed to impurity levels of 2-hydroxymethyl and 4-hydroxymethyl loratadine, so meeting those thresholds can create exposure even if a different stability approach is used.

4) How do the “sufficient to inhibit degradation” claims work?

Claims 14 and 16 require that the aminopolycarboxylic acid be present at an amount sufficient to inhibit loratadine degradation, which is a performance-based element.

5) What combo ingredients are explicitly named?

Pseudoephedrine and phenylpropanolamine are explicitly recited for decongestant embodiments (Claims 7, 8). The claims also allow adding a decongestant/analgesic/antitussive/expectorant in general terms (Claim 6), with analgesic dependencies (Claims 9, 10).

References

[1] U.S. Patent No. 6,132,758. “Antihistaminic syrup comprising loratadine and an aminopolycarboxylic acid,” claims as provided in the prompt.

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Details for Patent: 6,132,758

Summary for Patent: 6,132,758