Injectable formulations of anesthetics for any pathological pain
Inventors
Assignees
New Jersey Institute of Technology • Rutgers State University of New Jersey
Publication Number
US-12285528-B2
Publication Date
2025-04-29
Expiration Date
2039-10-31
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Abstract
An injectable formulation for a sustained-release of a local anesthetic is provided. The formulation comprises a pharmaceutically effective amount of a local anesthetic encapsulated into polymeric particles having a diameter from about 1 μm to about 4 μm. Such formulation prolongs analgesic effect, decreases toxicity, and allows loading larger doses, and at the same time is injectable directly at a patient's body site of the interest without generating a surgical wound. Methods of use and preparation are also provided.
Core Innovation
The invention provides an injectable formulation for the sustained-release of a local anesthetic. This formulation consists of a pharmaceutically effective amount of a local anesthetic encapsulated into polymeric particles with a diameter from about 1 μm to about 4 μm, and preferably from about 1 μm to about 2 μm. The selected polymers are biocompatible or biodegradable, including, for example, poly(lactic-co-glycolic acid) (PLGA), poly(lactic acid) (PLA), or poly(glycolic acid) (PGA).
The problem addressed is the inadequate management of pathological pain due to the short duration of analgesic effects and systemic toxicity of conventional local anesthetics. Traditional formulations are rapidly absorbed systemically, providing analgesia for only a short period and requiring repeated administration or continuous infusion through catheters, which can be invasive or require surgical intervention. Previous sustained-release formulations using larger polymeric particles were not injectable and required surgical placement, thus limiting minimally invasive application.
The core innovation lies in the use of polymeric microparticles with carefully controlled size—1 μm to 4 μm in diameter—allowing the formulation to be injected through standard needles (e.g., 25-gauge) directly at the site of interest. The encapsulated local anesthetic is released in a sustained, controlled manner for up to 14 days, prolonging analgesic effect, decreasing toxicity, and enabling higher loading doses than conventional approaches, all without generating a surgical wound.
Claims Coverage
The patent claims cover two independent inventive features centering on the specific injectable sustained-release formulation and its method of use for sustained pain relief.
Injectable sustained-release formulation using biodegradable polymeric particles with controlled size for delivering local anesthetic
An injectable formulation for treatment of pathological pain, comprising: - A pharmaceutically effective amount of a local anesthetic encapsulated into a plurality of polymeric particles. - Each particle has a diameter from 1 μm to 2 μm. - The local anesthetic has a concentration from 1.25 mg/mL to 20 mg/mL. - The polymer is a biodegradable polymer: poly(lactic acid) (PLA), poly(glycolic acid) (PGA), or poly(lactic-co-glycolic acid) (PLGA). - The formulation must be injectable with a 25-gauge needle.
Method for providing sustained pain relief at a site in a patient through administration of the defined injectable sustained-release formulation
A method involving: - Administering the injectable sustained-release formulation comprising a pharmaceutically effective amount of a local anesthetic encapsulated into a plurality of polymeric particles (as defined above) to a patient at a targeted site. - The local anesthetic may have a loading of 1% to 90% by weight into the particles. - The release is controlled (1 to 30 mg per hour at the release site for a duration ranging from 4 hours to 14 days).
In summary, the inventive features cover a specific size-controlled, biodegradable, injectable particle-based formulation of local anesthetic, as well as its method of use for providing sustained pain relief in patients.
Stated Advantages
The formulation prolongs analgesic effect at the site of interest.
It decreases toxicity compared to conventional local anesthetic formulations.
It enables loading of larger doses of local anesthetic into the injectable formulation.
The formulation can be injected directly at the patient's body site without generating a surgical wound.
Documented Applications
Management of pathological pain, such as incisional pain and neuropathic pain.
Management of chronic pain, including pain associated with various types of cancer.
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