Boosting Anti-Infective Activity with Muramyldipeptides and Liposomes
This patent describes a method to make anti-infective drugs called muramyldipeptides work better by injecting them separately but close in time with tiny fat bubbles called liposomes into an animal.
Original patent title: “Serial injection of muramyldipeptides and liposomes enhances the anti-infective activity of muramyldipeptides”
This patent describes a method to make anti-infective drugs called muramyldipeptides work better by injecting them separately but close in time with tiny fat bubbles called liposomes into an animal. Granted to Syntex USA LLC in 1985 with 10 claims and 2,340 forward citations.
Key facts
Coverage
What does this patent actually cover?
The patent details a method to improve how well muramyldipeptide (MDP) compounds fight infections. This involves giving an animal two separate intravenous injections: first, an unencapsulated MDP compound, and second, liposomes. The key is that these two injections must happen within three hours of each other, as stated in claimclaimA numbered sentence at the end of a patent that legally defines what the inventor owns. The most important section.Read more → 1. This serial injection approach enhances the MDP compound's ability to combat infections. For example, if a lab animal has a bacterial infection, this method could make the MDP treatment more effective than giving the MDP alone.
The gap
What does this patent NOT cover?
- Does not cover injecting the muramyldipeptide (MDP) compound directly inside the liposomes; it specifies 'unencapsulated MDP compound' in claimclaimA numbered sentence at the end of a patent that legally defines what the inventor owns. The most important section.Read more → 1.
- Does not cover administering the MDP compound and liposomes more than three hours apart, as claimclaimA numbered sentence at the end of a patent that legally defines what the inventor owns. The most important section.Read more → 1 requires them to be 'within three hours of each other'.
- Does not cover methods of delivery other than 'serial intravenous injection' (e.g., oral administration or intramuscular shots).
- Does not cover using MDP compounds or liposomes alone; the method requires both components to be serially injected.
- Does not cover applications outside of 'an animal in need thereof', meaning it's not for cell cultures or inanimate objects.
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
What made this novel
The noveltynoveltyThe requirement that an invention be different from anything publicly known before its priority date.Read more → lies in the specific timing and separate delivery of the unencapsulated muramyldipeptide and liposomes. Instead of combining them, the patent found that injecting them serially, within a short window, significantly boosts the anti-infective effect, suggesting a unique synergistic mechanism.
Schematic visualization of the patent's claim structure. Hand-drawn diagrams in progress for each landmark patent.
Where you've seen this
Real-world examples
Experimental immune-boosting therapies
Adjuvants in vaccine development
Research into host defense mechanisms against pathogens
Drug delivery systems in preclinical studies
Why it matters
The bigger picture
Enhancing the effectiveness of anti-infective agents is crucial for treating diseases and potentially combating drug resistance. This method aims to boost the body's immune response to fight off infections more efficiently. By making existing compounds like muramyldipeptides more potent, it could lead to better patient outcomes and potentially lower dosages of the active drug.
Filed
July 8, 1982
Granted
June 11, 1985
Market context
Who's building on this
Companies in this space
The original assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more →, Syntex USA LLC, was acquired by Roche, a major pharmaceutical company, which continues to be active in drug discovery and development. Companies involved in immunology, vaccine adjuvants, and advanced drug delivery systems, such as Moderna, BioNTech, and various biotech startups, are continuously exploring ways to enhance immune responses and drug efficacy, often using liposomal technologies or immune modulators similar to MDPs.
Market impact
This patent contributed to the understanding of how immune-modulating compounds like muramyldipeptides can be made more effective. While not creating an entirely new market, it provided a specific method for enhancing existing anti-infective strategies. This knowledge could inform the development of more potent treatments for various infections, potentially reducing treatment durations or improving outcomes for patients with compromised immune systems.
Claim 1 — Plain English
What this patent covers
The patent details a method to improve how well muramyldipeptide (MDP) compounds fight infections. This involves giving an animal two separate intravenous injections: first, an unencapsulated MDP compound, and second, liposomes. The key is that these two injections must happen within three hours of each other, as stated in claim 1. This serial injection approach enhances the MDP compound's ability to combat infections. For example, if a lab animal has a bacterial infection, this method could make the MDP treatment more effective than giving the MDP alone.
The clever bit
The novelty lies in the specific timing and separate delivery of the unencapsulated muramyldipeptide and liposomes. Instead of combining them, the patent found that injecting them serially, within a short window, significantly boosts the anti-infective effect, suggesting a unique synergistic mechanism.
What it does not cover
- Does not cover injecting the muramyldipeptide (MDP) compound directly inside the liposomes; it specifies 'unencapsulated MDP compound' in claim 1.
- Does not cover administering the MDP compound and liposomes more than three hours apart, as claim 1 requires them to be 'within three hours of each other'.
- Does not cover methods of delivery other than 'serial intravenous injection' (e.g., oral administration or intramuscular shots).
- Does not cover using MDP compounds or liposomes alone; the method requires both components to be serially injected.
- Does not cover applications outside of 'an animal in need thereof', meaning it's not for cell cultures or inanimate objects.
Patent timeline
Application submitted to the patent office
Application published, typically 18 months after filing
Patent officially issued
PatentBrief Score
Impact Score
Moderate
Citation count
40/40
Highly cited
Claim breadth
7/20
Moderate scope
Recency
0/20
Older than 20 years
Assignee scale
0/20
Independent or smaller assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more →
PatentBrief Impact Score — based on citation count, claim breadth, recency, and assignee scale. Not a legal assessment.
Heuristic Value Estimate
What this patent might be worth
$135K – $432K
Midpoint $270K · expired or expiring · industry ×3.0
Heuristic only — blends forward/backward citation counts, claim scope, time remaining, litigation history, and CPC-derived industry baseline. Real valuations need a professional appraisal.
The original legal language
Original claims
10 claims as filed with the patent office.
Concepts involved
Citations
Patent lineage
Cite this patent
Fraser-Smith, E. B., Matthews, T. R., & Eppstein, D. A. (1985). Boosting Anti-Infective Activity with Muramyldipeptides and Liposomes (U.S. Patent No. 4,522,811). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/4522811/human-growth-hormone-protropin
Auto-generated from the patent record. Double-check author order and the issue date against the official USPTO document before submitting.
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Common Questions
Frequently Asked Questions
What does Boosting Anti-Infective Activity with Muramyldipeptides and Liposomes cover?
This patent describes a method to make anti-infective drugs called muramyldipeptides work better by injecting them separately but close in time with tiny fat bubbles called liposomes into an animal.
Who owns patent US 4522811?
Syntex USA LLC owns this patent, granted in 1985.
When does this patent expire?
This patent has expired and is now in the public domain — anyone can use the invention freely.
What is patent US 4522811 cited by?
This patent has been cited by 2340 later patents that build on its ideas.
What problem does this patent solve?
Enhancing the effectiveness of anti-infective agents is crucial for treating diseases and potentially combating drug resistance. This method aims to boost the body's immune response to fight off infections more efficiently. By making existing compounds like muramyldipeptides more potent, it could lead to better patient outcomes and potentially lower dosages of the active drug.
What does this patent NOT cover?
Does not cover injecting the muramyldipeptide (MDP) compound directly inside the liposomes; it specifies 'unencapsulated MDP compound' in claim 1.
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