Levothyroxine PLGA Microparticles for Sustained Injectable Release
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Solution Overview
Problem
Current oral and injectable levothyroxine formulations require daily administration, lacking a sustained release formulation that reduces frequency and minimizes initial burst release, toxicity, and enhances patient compliance.
Innovation Solution
A sustained release injectable formulation using microparticles of levothyroxine or its pharmaceutically acceptable salt with a poly(D,L-lactide-co-glycolide) polymer, achieving a theoretical drug loading of at least 1.5% w/w, with controlled release over an extended period and reduced initial burst.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If levothyroxine is formulated in oral or conventional injectable forms, then the drug can be administered and absorbed, but it requires daily administration and has short duration of action
Solution Approach 1:
The levothyroxine is segmented into microparticles embedded within a biodegradable polymer matrix. This segmentation allows the drug to be released gradually as the polymer degrades, extending the duration of action from daily to monthly or longer intervals, thereby reducing dosing frequency while maintaining therapeutic effect.
Solution Approach 2:
The levothyroxine is pre-loaded into the polymer matrix during formulation, creating a reservoir that will release the drug over time. This preliminary encapsulation ensures sustained release without requiring repeated administration, effectively extending the duration of pharmacological action.
2Duration of action of moving object
If levothyroxine microparticles are prepared in polymer matrices, then the drug can be sustained for longer periods, but high initial burst release occurs causing side effects
Solution Approach 1:
The polymer matrix is designed with specific local properties including controlled porosity, hydrophobicity, and cross-linking density to modulate drug release. These localized characteristics prevent rapid initial release while maintaining sustained release capability, eliminating burst effects that cause side effects like restlessness, palpitations, and heart failure.
Solution Approach 2:
The formulation parameters of the polymer matrix are optimized including polymer composition (PLA, PLGA, PCL), molecular weight, crystallinity, and cross-linking degree. These parameter changes control the degradation rate and drug diffusion, achieving sustained release without initial burst while maintaining the desired duration of action up to two months.
3Quantity of substance
If high drug loading is achieved in the formulation, then the dosing volume is reduced, but the manufacturing precision becomes more difficult to control
Solution Approach 1:
Pharmaceutically acceptable excipients and surfactants are used as intermediaries during the microparticle fabrication process. These agents facilitate uniform drug distribution within the polymer matrix, ensuring consistent high drug loading (at least 1.5% w/w) while maintaining manufacturing precision and formulation reproducibility across batches.
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 formulation provides a pharmacological effect for at least a week up to two months with a single administration, improving patient compliance and reducing medical care costs.
Implementation Method 1
controlled release over an extended period
Implementation Method 2
microparticles of levothyroxine or its pharmaceutically acceptable salt with a poly(D,L-lactide-co-glycolide) polymer
Data Source
AI summary
A stable sustained release injectable formulation based on poly(D,L-lactide-co-glycolide) microparticles comprising levothyroxine is described. The formulation has a theoretical levothyroxine loading of at least 1.5% w/w. A process for preparing the microparticles is also described. The formulation may be used to control hypothyroidism in adults, congenital hypothyroidism in infants, and acquired hypothyroidism in children.