PLGA Progestogen Microspheres for Linear Sustained Release
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Solution Overview
Problem
Existing progestogen formulations, particularly those using PLGA microspheres, exhibit non-linear cumulative drug release profiles with either a high initial burst or a delayed lag phase, which is unsuitable for therapies requiring consistent drug delivery over several days.
Innovation Solution
Development of PLGA microspheres encapsulating progestogen drugs with a biodegradable polymer composition, designed to achieve a linear cumulative release profile without an initial burst or lag phase, suitable for parenteral administration, specifically for subcutaneous or intramuscular use, with a controlled release duration of at least 6 days.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If PLGA microspheres are used for sustained-release of progestogen drugs, then the dosing frequency is reduced and patient compliance is improved, but the drug release profile becomes non-linear with initial burst or lag phase
Solution Approach 1:
The patent modifies the polymer composition parameters by using specific ratios of lactide to glycolide (50:50 to 75:25) and controlling molecular weight (4,000 to 100,000 daltons) to achieve linear release kinetics. The polymer chain end groups (carboxyl- or ester-terminated) are also controlled to optimize the release profile, transforming the non-linear burst/lag phase pattern into a consistent linear release over 6-14 days.
Solution Approach 2:
The patent employs composite microsphere formulations combining PLGA polymers with specific drug loading ratios (10-50% progestogen by weight). The composite structure of polymer matrix and drug core, along with controlled porosity and surface properties, enables sustained linear release while maintaining biocompatibility and biodegradability.
2Reliability
If oil solution formulations are used for intramuscular administration of progesterone, then high serum levels are achieved, but severe pain and hypersensitivity reactions occur
Solution Approach 1:
The patent transitions from oil-based formulations to water-soluble PLGA microsphere suspensions, fundamentally changing the vehicle parameter. This eliminates oil-related tissue disruption while maintaining effective drug delivery. The microsphere size (20-150 μm diameter) and surface properties are optimized to reduce injection pain and improve tissue compatibility.
Solution Approach 2:
The patent uses biodegradable PLGA polymers that naturally degrade in the body over time, eliminating the need for long-term persistence of foreign materials. The microspheres are designed to be temporarily present (6-14 days release period) and then safely metabolized, reducing chronic tissue irritation and hypersensitivity risks associated with persistent oil formulations.
3Reliability
If repeated intramuscular injections are administered, then therapeutic effect is maintained, but local soreness and sterile abscess formation occur
Solution Approach 1:
The patent extends the therapeutic action duration from daily to weekly or bi-weekly injections by incorporating sustained-release PLGA microspheres. The dynamic release profile maintains steady drug levels over 6-14 days, eliminating the need for frequent injections that cause cumulative tissue damage. The biodegradable polymer dynamically degrades while releasing drug, providing continuous therapy without repeated mechanical trauma.
Solution Approach 2:
The patent pre-encapsulates the progestogen drug within PLGA microspheres before administration, creating a reservoir that releases drug gradually. This preliminary encapsulation action prevents direct contact of bulk drug or oil vehicle with tissue, reducing acute inflammatory responses and sterile abscess formation while maintaining therapeutic efficacy over extended periods.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The microspheres provide a reliable and effective method for sustained release of drugs, ensuring a linear cumulative release profile of progestogen drugs, achieving consistent drug delivery over several days without initial burst or lag phase, thereby improving patient compliance and reducing discomfort.
Implementation Method 1
microspheres comprising a progestogen drug encapsulated by a PLGA biodegradable polymer
Implementation Method 2
exhibit a linear cumulative release profile until about 70% or more of the progestogen is released from the microspheres
Data Source
AI summary
The present invention relates to injectable microspheres and formulations comprising the microspheres for controlled release of progestogen hormones. The present invention also relates to a method of preparing the microspheres that control the release of the progestogen hormone and methods of using the microspheres that control the release of the progestogen hormone to treat conditions such as pregnancy and fertility in women as well as gynecological disorders such as secondary amenorrhea, endometriosis, abnormal uterine bleeding due to hormonal imbalance, and acne.