Scope and Patent Landscape for US Patent 5,169,849 (Dihydroergotamine + Xanthine for Nasal Ciliary Modulation)

Executive summary: US 5,169,849 claims liquid nasal compositions and nasal administration methods that pair dihydroergotamine (DHE) with a ciliary-function-increasing xanthine (theophylline or caffeine, among others), using defined DHE:xanthine weight ratios (about 0.1:1 to 10:1). The patent further narrows scope to specific DHE salt form (mesylate), optional isotonizing agents (including glucose, with specific ratios), defined osmotic pressure (280 to 360 mOsm/L), and delivery format constraints (solution, nasal spray applicator, and droplet size 800 to 1000 microns). The estate’s competitive relevance for US generic or reformulation entry depends on whether later commercial products (and any Orange Book-listed NDAs) practice these exact combinations and constraints, and whether separate patents cover (i) DHE nasal products, (ii) caffeine/theophylline inclusion, (iii) ciliary-function modulation as a mechanism, and (iv) nasal device and performance parameters. The claims are structurally broad on “xanthine” class selection, but functionally and parameter-specifically narrow on formulation attributes and administration context.

What is US Patent 5,169,849 and what does it claim for dihydroergotamine nasal delivery?

Short answer: US 5,169,849 is a formulation-and-method patent focused on nasal delivery of DHE using a paired ciliary depressant (DHE) and a ciliary function-increasing xanthine (theophylline/caffeine), with defined weight ratios and optional salt, tonicity, osmotic pressure, and applicator/droplet parameters.

Claim set overview (as provided)

Composition claims

Claim 1: Liquid nasal pharmaceutical composition containing:
- DHE (pharmaceutically effective amount; depresses ciliary function)
- Xanthine (effective amount; increases ciliary function)
- DHE:xanthine weight ratio about 0.1:1 to 10:1
Claim 2: DHE is mesylate
Claim 3-5: Xanthine structure-defined; examples include theophylline and caffeine
Claim 6-10: Optional isotonizing agent (non-toxic), sugar preferred; example glucose; ratios tied to isotonizing agent
Claim 11: composition in solution form
Claim 12: osmotic pressure 280 to 360 mOsm/L
Claim 13: unit dosage saturated with carbon dioxide gas
Claim 14-15: nasal spray applicator; droplet size 800 to 1000 microns
Claim 16: specific preferred combination: DHE mesylate + caffeine at DHE:caffeine 1:0.1 to 1:1 plus glucose

Method claims

Claim 17: Nasal co-administration of DHE and xanthine with same DHE:xanthine ratio range (0.1:1 to 10:1); DHE depresses ciliary function; xanthine increases it
Claim 18: treating hypotension or migraine
Claim 19: DHE is mesylate
Claim 20-23: xanthine definition; examples theophylline/caffeine; dose 2 to 20 mg xanthine per dose
Claim 24-25: administering spray of liquid; osmotic pressure 280 to 360 mOsm/L
Claim 26: spray of powder (non-liquid spray embodiment)
Claim 27-30: co-administer non-toxic isotonizing agent; sugar preferred; glucose example; sugar dose 10 to 100 mg
Claim 31: DHE dose 0.5 to 5 mg per dose

How broad are US 5,169,849 claims on dihydroergotamine-to-xanthine ratio and xanthine identity?

Short answer: The core inventive claim hinge is DHE plus a ciliary-function-increasing xanthine at a specified weight ratio range. The xanthine identity is class-linked by structural general formula plus explicit embodiments for theophylline and caffeine.

Ratio scope (primary infringement lever)

Claim 1 / 17: DHE:xanthine weight ratio about 0.1:1 to 10:1
- This is broad across three orders of magnitude in ratio terms, enabling formulation flexibility.
- “About” increases tolerance for minor deviations.

Xanthine scope

Claim 3 / 20: xanthine chosen from a general formula where R1, R2, R3 are hydrogen or alkyl C1-10 (as indicated in the text you provided).
Claim 4 / 21: theophylline
Claim 5 / 22: caffeine

Practical impact for design-around:

A competitor that uses a different ciliary-supporting agent that is not a “xanthine” within the defined formula likely falls outside the literal scope.
A competitor that uses theophylline or caffeine but uses a DHE:xanthine ratio outside 0.1:1 to 10:1 creates a potential literal avoidance path, but “about” narrows how far outside you can be while remaining safe.

Does US 5,169,849 require mesylate or can other DHE salts infringe?

Short answer: The base claims (1 and 17) do not expressly limit DHE to a specific salt, but dependent claims do. Whether the patent reaches other DHE salts depends on whether the independent claims interpret “dihydroergotamine” to include pharmaceutically effective salts as equivalents in claim construction.

Salt-related claim structure

Dependent claim 2: DHE present is mesylate
Dependent method claim 19: DHE is mesylate

Scope reading (based on claim text provided):

If the independent claim term “dihydroergotamine” is construed to encompass DHE salt forms, then other salts could still infringe claim 1/17 when paired with an appropriate xanthine ratio.
If claim construction restricts “dihydroergotamine” to the specific examples/salt where the specification or prosecution history limits interpretation, then claim 2/19 become the primary literal targets.

Business takeaway: Licensing leverage and clearance risk should be evaluated assuming salt flexibility in claim 1/17, then pressure-tested against any later construction or cited prior art that might narrow scope.

What formulation parameters are locked in: osmotic pressure, isotonizing agent, glucose ratios, and carbon dioxide saturation?

Short answer: Several dependent claims lock formulation performance parameters that can materially affect both product design and patent-risk screening.

Osmotic pressure limits (device/formulation-specific)

Claim 12 (composition): osmotic pressure 280 to 360 mOsm/L
Claim 25 (method): osmotic pressure 280 to 360 mOsm/L for the liquid spray embodiment

Risk effect:

If a competitor’s product osmolarity is outside 280 to 360 mOsm/L, they may avoid dependent claims 12/25, but claim 1/17 could still be asserted unless osmolarity is treated as an implicit requirement for the independent claim.

Isotonizing agent and glucose constraints

Claim 6: includes non-toxic isotonizing agent
Claim 7: weight ratio of ciliary function increasing agent to isotonizing agent from 1:0.05 to 1:10
Claim 8-10: isotonizing agent is sugar; sugar is glucose; ratio of ciliary function increasing agent to glucose from 1:1 to 1:10

Key point: These are “ratio-of-ingredients” constraints, not a generic “include sugar.” That narrows the practical design-around space: keeping sugar out is one path, but the ratio constraints can create literal infringement risk if included at the specified tonicity strategy.

Carbon dioxide saturation (unit dose)

Claim 13: unit dosage form saturated with carbon dioxide gas

Device and delivery relevance:

Carbon dioxide saturation can imply headspace/gas handling, propellant-free aerosolization strategies, and stability controls. Products without CO2 saturation are more likely to avoid claim 13.

How restrictive are the nasal spray applicator and droplet size claims?

Short answer: Claims 14-15 lock a nasal spray applicator and a droplet size range of 800 to 1000 microns. These are likely to be product-specific and can create a strong non-infringement argument for different device/atomization strategies.

Applicator constraints

Claim 14: nasal spray applicator
Claim 15: spray applicator produces droplet size 800 to 1000 microns

Design-around logic:

If a product uses a different droplet size distribution (or different spray technology not matching 800 to 1000 microns), it may avoid claim 15 while still potentially falling under claim 14 or the broader independent method claim 17 depending on how delivery is characterized.

What delivery formats are covered: solution vs powder spray?

Short answer: The patent covers both liquid spray (claims 11, 24-25) and spray of powder (claim 26).

Covered embodiments

Claim 11: solution
Claim 24: method wherein a spray of liquid is administered
Claim 25: liquid spray with osmotic pressure 280 to 360 mOsm/L
Claim 26: spray of powder

Impact:

Even if a competitor shifts from liquid to powder, the xanthine/DHE ratio and nasal co-administration elements remain central. A powder formulation could still trigger claim 17 unless claim 26 is read as an independent-format requirement or limitation tied to other dependent features.

Do the method claims cover migraine and hypotension, and how does that affect enforcement?

Short answer: Claim 18 expressly limits one method embodiment to treating hypotension or migraine, but the core method claim 17 already covers nasal co-administration with ratio limits.

Indication-specific claim

Claim 18: treating hypotension or migraine

Enforcement implications:

Indication-specific claims can support narrower licensing and litigation based on the intended use described in prescribing information or clinical labeling.
However, claim 17 (if not limited by indication) can still support broad enforcement based on administration practice.

How does this patent compare with adjacent DHE nasal product IP: where do other patents typically overlap?

Short answer: For DHE nasal products, adjacent IP usually clusters into (i) active ingredient salt/form, (ii) nasal formulation excipients/tonicity and stability, (iii) device delivery mechanics, and (iv) dosing regimens and indications. US 5,169,849 sits at the intersection of (ii) and (iii) but also anchors a specific combination rationale: DHE as a ciliary depressant paired with xanthine as a ciliary-function increasing agent.

Typical overlap risk zones for competitors

DHE nasal composition patents:
- excipient selection
- tonicity control strategy
- pH/stability specifications
- viscosity and spray behavior
DHE dosing patents:
- mg per dose ranges
- frequency schedules
- regimen for migraine/hypotension
Ciliary/transport modulation patents:
- pairing “mucociliary clearance modulation” agents with penetration-enhancing agents
- nasal physiologic targeting

Competitive reading: If a generic reformulation changes excipients but maintains DHE:xanthine within 0.1:1 to 10:1, it may still fall into the “core combination” claims. If it changes the ratio or replaces caffeine/theophylline with a non-xanthine modulator, the main claim may be avoided while still leaving dependents (osmolarity, glucose ratio, droplet size) as secondary constraints.

Where are potential infringement choke points: which claim elements are most likely to be determinative in litigation?

Short answer: The most determinative elements for infringement or non-infringement are (1) whether a xanthine is present and meets the formula-defined scope (and is not merely a similar methylxanthine analog), (2) whether the DHE:xanthine weight ratio falls within 0.1:1 to 10:1, and (3) whether formulation/device parameters match dependent claim constraints (osmotic pressure, droplet size, glucose ratio, CO2 saturation).

High-friction elements

DHE + xanthine pairing
Weight ratio 0.1:1 to 10:1
Osmotic pressure 280 to 360 mOsm/L (for dependent claim 12/25)
Droplet size 800 to 1000 microns (for dependent claim 15)
Glucose/isotonizing agent ratios and sugar inclusion (claims 6-10)
CO2 saturation (claim 13)

What generic entry risks exist for DHE nasal products under this claim?

Short answer: Risk concentrates on products that attempt to replicate a DHE nasal formulation while using caffeine or theophylline as a ciliary modulator at similar ratios and with similar tonicity/spray performance. Generic entry risk rises when the competitor’s formulation appears “close” rather than substitutive.

Generic risk matrix (based on claim logic)

Competitor design choice	Likely exposure to US 5,169,849
Uses DHE + caffeine/theophylline within 0.1:1 to 10:1	High
Uses DHE + xanthine but ratio outside 0.1:1 to 10:1	Medium (independent may still be asserted depending on construction of “about” and practice details)
Uses DHE but replaces xanthine with non-xanthine ciliary modulator	Lower for combination core (claim 1/17), depends on whether substitute is argued to be within xanthine definition
Keeps DHE + xanthine but changes osmotic pressure outside 280-360 mOsm/L	Avoids dependents 12/25; independent still possible
Keeps core but changes device to avoid 800-1000 micron droplet size	Avoids dependent 15; independent still possible
Changes delivery from liquid spray to powder spray	Potentially reduces dependent 24/25 but claim 17/26 still risk

What would the patent estate look like beyond US 5,169,849: continuations, related patents, and typical continuation coverage?

Short answer: Without the patent family listing, continuation chain, and prosecution history, a complete estate map cannot be produced. The claim scope you provided indicates a typical formulation+method patent that often appears alongside:

salt form patents (DHE mesylate),
excipient/tonicity patents (glucose or other sugars, osmolarity windows),
device/pump/spray parameter patents (droplet size),
dosing regimen patents (0.5 to 5 mg DHE, xanthine 2 to 20 mg per dose).

Actionable limitation: A “full landscape” requires the complete family and citation set; that is not available in the input provided.

Orange Book and FDA pathway status: how does exclusivity affect enforcement for US 5,169,849?

Short answer: A definitive Orange Book and FDA exclusivity position cannot be established from the information provided. The patent’s enforcement utility depends on whether it is listed for an FDA-approved product and on the exclusivity timeline for that specific NDA.

Key Takeaways

US 5,169,849 anchors protection around a specific nasal therapeutic concept: co-formulation and co-administration of DHE with a ciliary-function-increasing xanthine.
The core independent scope (claims 1 and 17) is driven by DHE:xanthine weight ratio about 0.1:1 to 10:1 and the presence of a xanthine within a defined structural scope (with caffeine/theophylline explicit).
Dependent claims narrow to formulation and delivery parameters: DHE mesylate, osmotic pressure 280-360 mOsm/L, glucose as sugar isotonizing agent with ratio constraints, CO2 saturation, and spray droplet size 800-1000 microns.
For generic/reformulation strategy, the highest leverage design-around variables are:
1. removing the xanthine (or using non-xanthine ciliary modulators),
2. moving the DHE:xanthine ratio outside the claimed range,
3. changing osmolarity,
4. changing device droplet size distributions,
5. removing CO2-saturated unit-dose features.

FAQs

1) What happens if a nasal product includes DHE and caffeine but uses a DHE:caffeine ratio slightly outside 0.1:1 to 10:1?
Risk shifts away from literal coverage of the independent ratio limitation, but “about” can still create infringement arguments depending on how closely the ratio is matched in practice.

2) Does using a different sugar instead of glucose avoid the patent?
It may avoid dependent glucose-specific claims (8-10, 9-10), but claim 6-7 could still apply if a non-toxic isotonizing agent and the relevant ratios align.

3) If osmotic pressure is adjusted outside 280-360 mOsm/L, is the product safe?
It avoids dependent claims 12 and 25, but independent claims 1 and 17 may still be asserted if their limitations do not require osmotic pressure.

4) Are powder nasal sprays automatically non-infringing because the patent includes liquid-specific osmotic claims?
No. Claim 17 covers nasal co-administration broadly, and claim 26 includes “spray of powder,” so powder does not eliminate core risk.

5) Can a product infringe if it treats indications other than migraine or hypotension?
Yes. Claim 18 is indication-specific, but claim 17 covers the administration concept and ratio framework without needing an explicit migraine/hypotension label.

References (APA)

US Patent 5,169,849. (n.d.). Dihydroergotamine and xanthine nasal compositions and methods.

Foriegn Application Priority Data
Foreign Country	Foreign Patent Number	Foreign Patent Date
United Kingdom	8202781	Feb 01, 1982

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Austria	385656	⤷ Start Trial
Austria	A30383	⤷ Start Trial
Australia	1085083	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 5,169,849

Summary for Patent: 5,169,849