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Simultaneous Label-Free Autofluorescence Multi-Harmonic Microscopy
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Kinetic Modeling of Accelerated Stability Testing Enabled by Second Harmonic Generation Microscopy.

Zhengtian Song1,2, Sreya Sarkar1,2, Andrew D Vogt2

  • 1Department of Chemistry , Purdue University , 560 Oval Drive , West Lafayette , Indiana 47906 , United States.

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|March 6, 2018
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This summary is machine-generated.

Second harmonic generation (SHG) microscopy allows for highly sensitive detection of active pharmaceutical ingredient (API) crystallization in amorphous solid dispersions (ASDs). This method enables precise kinetic modeling of crystallization processes, crucial for drug stability testing.

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Area of Science:

  • Pharmaceutical Sciences
  • Materials Science
  • Chemical Engineering

Background:

  • Amorphous solid dispersions (ASDs) enhance solubility of poorly soluble active pharmaceutical ingredients (APIs).
  • Stability testing of ASDs is critical for drug product development and shelf-life determination.
  • Early detection of API crystallization is a key challenge in ASD stability assessment.

Purpose of the Study:

  • To quantitatively model the temperature-dependent crystallization kinetics of ritonavir in ASDs.
  • To evaluate the utility of second harmonic generation (SHG) microscopy for sensitive detection of API crystallization.
  • To compare the limit of detection of SHG microscopy with existing methods for ASD crystallinity analysis.

Main Methods:

  • Accelerated stability testing of ritonavir ASDs at 50°C/75%RH and 40°C/75%RH.
  • Monitoring of ritonavir crystallization using SHG microscopy coupled with image analysis.
  • Quantitative kinetic modeling using the Johnson-Mehl-Avrami-Kolmogorov (JMAK) model.

Main Results:

  • SHG microscopy achieved a limit of detection for ritonavir crystals as low as 10 ppm.
  • This detection limit is approximately two orders of magnitude lower than conventional methods.
  • Independent determination of nucleation and crystal growth rates was achieved through quantitative modeling.

Conclusions:

  • SHG microscopy offers unprecedented sensitivity for detecting API crystallization in ASDs.
  • The quantitative modeling capabilities of SHG microscopy facilitate accurate assessment of ASD stability.
  • This technique significantly advances the characterization and stability testing of amorphous solid dispersions.