Electrostatic dry powder coated moisture barrier films for Compound Danshen Tablets / 中草药

ABSTRACT

Objective: Using ultrafine hydroxypropyl cellulose (HPC) powders as coating material to prepare moisture barrier coating film for Compound Danshen Tablets by an innovative electrostatic powder coating technology. The effects of coating prescription and process parameters on coating efficiency and coating film properties were investigated, so as to provide new ideas for moistureproof coating of moisture sensitive traditional Chinese medicine such as Compound Danshen Tablets. Methods: Free films were prepared by applying an electrostatic deposition process, and the effects of liquid plasticizer on the mechanical properties and the water vapor permeability were investigated. And the Compound Danshen Tablets were dry coated with ultrafine powders by the electrostatic coating technology. The effects of coating formulations and processing conditions on the moisture sorption behavior of the barrier film coated tablets were studied. Results: The coating efficiency could be manipulated by adjusting the charging voltage of the electrostatic spray gun and the amount of the liquid plasticizer. Compared with static curing process, dynamic curing process was capable to produce a satisfactory film with an enhanced moisture barrier function for the herbal medicines. The best coating process parameters were plasticizer spraying time 3 min and titanium dioxide addition ratio 1%. The minimum hygroscopicity was achieved when the coating level was increased to 6.7%. Conclusion: The moisture-protective effect by using a novel electrostatic coating technology with ultrafine powders was efficiently achieved, suggesting that it was a promising alternative for the protection for the moisture sensitive drugs.