The First Discovery of a Microstructure in Black Plaster and Its Performance Characterization

Area of Science:

• Traditional Chinese Medicine
• Materials Science
• Pharmacology

Background:

• Black plaster is a traditional external dosage form of Chinese medicine, used since ancient times.
• Goupi Gao is a representative black plaster ointment with a long history of external application.
• This study investigates the scientific characteristics of the black plaster dosage form using Goupi Gao as a model.

Purpose of the Study:

• To characterize the microstructure of black plaster using Field Emission Scanning Electron Microscope - Image Processing (FESEM-IPP).
• To analyze the release behavior of active components from Goupi Gao at different temperatures.
• To evaluate the impact of temperature on the physical properties of black plaster.

Main Methods:

• Established FESEM-IPP for morphological and quantitative characterization of black plaster microstructure.
• Investigated Goupi Gao release at 28°C, 35°C, and 45°C using the paddle over disk method.
• Analyzed cinnamaldehyde and eugenol content using Ultra-Performance Liquid Chromatography (UPLC).

Main Results:

• Goupi Gao and blank matrix formed a double continuous phase system with oil and soap crystal fibers.
• Pore area significantly increased with temperature (28°C: 216.8±59.5 μm², 35°C: 259.7±52.8 μm², 45°C: 408.0±57.7 μm²).
• No significant differences were observed in other pore parameters with varying temperatures.

Conclusions:

• The unique structure of black plaster supports its application in various medications.
• Black plaster exhibits favorable slow-release properties and performs well in extreme temperatures.
• The dosage form demonstrates good adhesion and peeling characteristics.