Hydrophilic Microspheres for Sustained Hydrophobic Drug Release
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current drug delivery systems face challenges in achieving sustained and non-burst release of hydrophobic drugs like paclitaxel and rapamycin, particularly in hydrophobic polymer systems, due to poor compatibility and rapid initial drug release, which limits their effectiveness in embolization therapy for tumors.
Innovation Solution
A new process for forming drug-loaded hydrophilic microspheres involves contacting water-insoluble, hydrophilic polymer particles with a drug solution in an aprotic solvent, followed by precipitation and rinsing to create a homogeneous core with a drug-rich interior and a thin surface layer, ensuring controlled release and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If hydrophobic polymer systems are used to deliver hydrophobic drugs, then drug solubility is improved, but rapid initial drug release (burst release) occurs
Solution Approach 1:
The patent changes the fundamental parameter of polymer hydrophobicity to hydrophilicity, using hydrophilic polymers (polyvinyl alcohol, polyacrylamide, gelatin, collagen, chitosan) to deliver hydrophobic drugs. This parameter change prevents burst release while maintaining drug solubility through the unique mechanism of drug precipitation within the hydrogel matrix during water absorption, enabling sustained release over days to weeks.
2Duration of action of moving object
If hydrophilic polymer systems are used to deliver hydrophobic drugs, then sustained release is improved, but drug compatibility is worsened
Solution Approach 1:
The patent exploits phase transition of the hydrophobic drug from dissolved state in organic solvent to precipitated state within the hydrogel matrix upon water absorption. The drug transitions from being soluble in the organic crosslinking agent during formulation to precipitating as fine crystals within the hydrogel network when exposed to aqueous environment, providing stable long-term retention and sustained release without degradation.
3Stability of the object's composition
If organic crosslinking agents are used in hydrogel formation, then gel structure stability is improved, but residual solvent toxicity is worsened
Solution Approach 1:
The patent employs volatile organic crosslinking agents (dioxane, ethyl acetate, acetone) that completely evaporate during the drying process, leaving no residual toxic solvent in the final product. These short-living solvents provide temporary structural support during gel formation but are completely removed before implantation, eliminating toxicity concerns while maintaining gel stability.
4Manufacturing precision
If drug is loaded uniformly throughout the polymer matrix, then drug distribution is improved, but surface drug release is worsened
Solution Approach 1:
The patent creates local quality differentiation through drug precipitation within the hydrogel matrix. The drug is uniformly distributed during formulation but locally precipitates in specific regions within the gel network upon water absorption, creating zones of high drug concentration embedded within the gel structure. This local precipitation prevents surface-level drug availability and eliminates burst release while maintaining overall uniform distribution.
Data Source
Figure 1
Figure 2~3D
Figure 4
AI summary
A process is described for loading hydrophilic polymer particles with a water-insoluble solvent-soluble drug. The particles are preferably embolic agents. The method provides particles having little or no drug at the surface and in a surface layer, whereby the burst effect is minimised. The drug is precipitated in the core of the particle, leading to extended release. The drug is, for instance, paclitaxel, rapamycin, dexamethasone or ibuprofen.