Polyoxaester Suspensions for Osmotic Pump Stability
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Solution Overview
Problem
Existing pharmaceutical suspensions face challenges in maintaining stability and preventing pluggage in osmotic drug delivery devices due to phase separation and high viscosity, which affects the reliability and flowability of the suspending vehicles, especially when exposed to aqueous media.
Innovation Solution
The use of polyoxaesters as suspending vehicles, formed from diacids and diols, provides a stable, virtually solvent-free, and one-phase environment for pharmaceutical agents, maintaining stability and flowability even when contacted with water, thus preventing phase separation and pluggage in osmotic pump-driven dosage forms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If high viscosity biocompatible polymers are used as suspending vehicles, then the sedimentation rate of pharmaceutical agent is slowed, but the suspending vehicle becomes difficult to pump through narrow exit ports and may form highly viscous almost solid formations
Solution Approach 1:
The patent changes the chemical structure parameters of the polymer by introducing oxane rings (cyclic ether structures) at regular intervals along the polymer backbone. This structural modification fundamentally alters the polymer's physical properties, reducing viscosity while maintaining suspension stability, thereby resolving the contradiction between suspension stability and pumpability.
Solution Approach 2:
The patent creates a composite polymer structure combining hydrophobic segments (providing structural integrity and suspension stability) with hydrophilic oxane ring segments (reducing viscosity and improving flow). This composite approach allows the material to exhibit both high suspension stability and good pumpability simultaneously.
2Reliability
If water-immiscible solvents are used in suspending vehicles, then water ingress into dosage forms is limited, but phase separation occurs at organic/aqueous interface when polymers like PVP are used
Solution Approach 1:
The patent applies local quality by creating a polymer with heterogeneous structure at the molecular level - hydrophobic segments provide the water-blocking property while hydrophilic oxane segments provide water compatibility. This local differentiation within the polymer chain allows the material to simultaneously protect from water ingress and maintain phase stability.
Solution Approach 2:
The oxane-containing polymer acts as an intermediary substance that bridges the incompatibility between water-immiscible solvents and aqueous media. The amphiphilic nature of the polymer (having both hydrophobic and hydrophilic character) allows it to stabilize the interface and prevent phase separation while maintaining the protective barrier against water ingress.
3Reliability
If suspending vehicles are made substantially solvent-free, then stability environment for proteins and peptides is improved, but achieving desirable suspension characteristics becomes more difficult
Solution Approach 1:
The patent changes the molecular weight parameters and chemical structure of the polymer to achieve the desired balance. By optimizing the polymer's structural parameters (oxane ring placement, chain length, molecular weight), the formulation achieves stable suspension characteristics without requiring additional solvents, thus maintaining drug stability while simplifying the formulation process.
Data Source
AI summary
Liquid polyoxaester polymer materials are provided as suspending vehicles suitable for dispensing of pharmaceutically active agents, such as proteins, from delivery devices, for example, pump-driven dosage forms. Polyoxaesters are made from at least one diacid and at least one diol. Through the use of polyoxaesters virtually solvent-free pharmaceutical suspensions can be created.