Stable Sepiapterin Polymorphs Identified by X-Ray Diffraction
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Solution Overview
Problem
Sepiapterin has limited stability in solutions and degrades under oxidative conditions, posing challenges for its use as a therapeutic agent due to its instability in solid forms.
Innovation Solution
Development of stable crystalline and amorphous forms of sepiapterin free base and its salts, characterized by specific X-ray diffraction peaks, which enhance stability and facilitate effective conversion to tetrahydrobiopterin (BH4) for therapeutic applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sepiapterin is used as a therapeutic agent, then it can effectively increase BH4 levels and treat diseases associated with low intracellular BH4, but it degrades under oxidative conditions and has limited stability in solutions and solid forms
Solution Approach 1:
The patent applies parameter changes by discovering and characterizing multiple crystalline polymorph forms of sepiapterin (Forms A through G), each with distinct X-ray diffraction patterns and stability characteristics. By changing the crystal structure parameters, the patent achieves improved chemical stability while maintaining the therapeutic function of increasing BH4 levels. For example, Form C shows enhanced stability compared to other polymorphs, demonstrating how parameter changes in crystal structure resolve the stability contradiction.
Solution Approach 2:
The patent creates composite material systems by formulating sepiapterin with various excipients and carriers in pharmaceutical compositions. These composite formulations protect sepiapterin from oxidative degradation while maintaining its bioavailability. The composite approach allows combining sepiapterin with stabilizing agents that prevent degradation under oxidative conditions, thus resolving the contradiction between therapeutic efficacy and chemical stability.
2Stability of the object's composition
If crystalline forms of sepiapterin are developed to improve stability, then chemical stability is enhanced, but the complexity of characterization and quality control increases
Solution Approach 1:
The patent replaces complex stability testing methods with X-ray diffraction (XRD) characterization to identify and differentiate crystalline polymorph forms. Each polymorph has a unique XRD fingerprint, allowing for straightforward identification and quality control. This substitution of characterization methods simplifies the complexity of monitoring and ensuring the stability of different crystalline forms while maintaining rigorous quality standards.
3Reliability
If sepiapterin is administered to treat phenylketonuria and other BH4-related disorders, then therapeutic efficacy is achieved by increasing BH4 levels, but the limited stability in solutions affects storage and administration
Solution Approach 1:
The patent applies preliminary action by pre-converting sepiapterin into stable crystalline polymorph forms and pharmaceutical compositions before administration. This preliminary stabilization ensures that the compound remains stable during storage, transport, and shelf-life, while maintaining its ability to convert to BH4 in vivo. The pre-formed crystalline structures and formulations are designed to remain stable until the moment of administration, at which point they effectively increase BH4 levels for treating phenylketonuria and other BH4-related disorders.
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 stable forms of sepiapterin provide improved stability and efficacy in treating diseases associated with low intracellular BH4 levels, such as phenylketonuria, by effectively increasing BH4 levels and enhancing the activity of related enzymes.
Implementation Method 1
having at least one peak at diffraction angle 2θ (°) of 8.4°±0.5, 16.9°±0.5, or 25.4°±0.5 as measured by X-ray diffractometry
Implementation Method 2
as measured by X-ray diffractometry by irradiation with Cu Kα X-rays
Implementation Method 3
having an endothermic peak at a temperature of 195° C.±5° C. in differential scanning calorimetry (DSC) profile
Data Source
AI summary
Disclosed are crystalline forms of sepiapterin free base selected from polymorphs A, B, C, D, E, F, and G, and combinations thereof, as well as crystalline polymorphs of salts of sepiapterin. Also disclosed are pharmaceutical compositions containing one or more such polymorphs and methods for preparing such polymorphs. Sepiapterin is useful in the treatment of a number diseases associated with low cellular levels of BH4, for example, phenylketonuria.