Advanced Analysis of Sustained-Release Drug Morphology Using Scanning Electron Microscopy (SEM)
What are Sustained-Release Drugs?
Sustained-release drugs refer to formulations that release the drug slowly and at a non-constant rate within a designated release medium after oral administration. Compared to conventional formulations, sustained-release drugs reduce the frequency of dosing and can significantly enhance patient compliance or minimize the side effects of the drug.
How to Formulate Sustained-Release and Controlled-Release Preparations?
Controlling the Dissolution Rate: Controlled-release preparations can be achieved by reducing the drug's dissolution rate.
Controlling the Diffusion Rate: In diffusion systems, the release rate is controlled through diffusion via an inert membrane.
Utilizing Osmotic Action: Preparations based on osmotic pressure principles release the drug evenly at a constant rate.
SEM Applications in Drug Morphology Analysis
This study employs the COXEM EM-30 series TT-SEM to characterize the morphology of sustained-release drugs, offering resolutions up to 5 nm at 30 kV. The COXEM CP-8000+ cross-section polisher, utilizing an argon ion beam, prepares particle cross-sections with minimal physical deformation or structural damage.
Ion Exchange Method: Charged drugs bind to resins. When ions with the appropriate charge interact with ion exchange groups, the drug is released through ion exchange.
This study utilizes the COXEM EM-30AX TT-SEM from Korea to observe the morphology of sustained-release drugs, with a resolution of up to 5nm at 30kV.
For particle cross-section preparation, the COXEM CP-8000+ is an advanced sample preparation tool that employs an argon ion beam to etch the sample's cross-section. This process prevents physical deformation and structural damage. It is capable of processing clean, large areas ranging from tens of micrometers to several millimeters. Its features are as follows:
- A high etching rate of 700 μm per hour (based on Si, 8 kV)
- Ability to save/load recipes that are frequently used
- Step by step recipes with automatic execution function
- Easy to load sample using smart sample holder
- Real-time observation of ion beam status and etching status through chamber camera
- Convenient operation - intuitive GUI and easy touch screen
- Minimizes thermal damage with the ion beam Auto On/Off function
- Fast and convenient sample alignment with ion beam using built-in digital microscope
- Provided with noise, vibration, oil-free diaphragm pump
- Flat milling function provided for plane etching of a large areas
Figure 2 shows that the generic drug particles have a relatively regular spherical crystalline structure, with a higher number of broken particles. The particle size ranges from approximately 2.0 to 20.0 μm, and the surface of the particles has holes ranging from 200 to 500 nm. The cross-sectional view of the drug also reveals internal voids, which are typically used for drug loading.
Figure 3 shows that the innovator drug particles are approximately 2.0 to 20.0 μm in size, with fewer surface holes and a smoother surface. Broken particles are rare. The cross-sectional view indicates that the internal voids are more abundant than in the generic drug, with sizes ranging from approximately 200 nm to 2.0 μm.
?When comparing the generic drug to the innovator drug, it is clear that the particle sizes are roughly the same, but the innovator drug particles are more uniform, with smaller surface holes, which helps in slower release. Additionally, the innovator drug has more internal voids, which helps control the drug loading. The experimental results also confirm that the innovator drug is more effective than the generic drug.
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