Application of Microwave Drying Sterilization Technology in Pharmaceutical Production

The factors affecting the quality of pills were investigated by orthogonal experiment. The results showed that the quality of pills dried by microwave was better than that dried by oven. The water content was uniform and the qualified rate of the first test of dissolution time was high.

Microwave drying and sterilization technology was used to test five products of different pill types, and the drying effect and product quality were investigated. The selected medicines are Naoliqing pills (containing aromatic ingredients), Zanlian pills (containing animal gum and animal organs), Maren pills (containing lipid ingredients), Wuziyanzong pills (containing sugar and lipid ingredients) and Qingshen Xiaopang pills (containing extract) with concentrated honey pills. All the above medicines are prepared by extensive preparation method. According to the characteristics of different kinds of pellets and the moisture content of wet pellets, the feed thickness of pellets is controlled below 3 cm, and the speed of conveyor belt of transmission device is adjusted to 80 r/min, 100 r/min and 200 r/min, respectively. The drying sterilization experiment is carried out with the moisture content of dry pellets as the process control index. The quality indexes of the dried pills, such as properties, identification, weight difference, dissolution time, water content and microbial limit test, were all in accordance with the requirements.

The results showed that the microwave drying effect was related to the ingredients of medicinal materials in the pills. Honey pills containing sugars, oils, gums, animal organs and extracts had a slower internal moisture diffusion rate, and the low-speed and long-time drying process was suitable. The water pills containing volatile components had a faster internal moisture and volatile components diffusion rate, so it was better to use high-speed and short-speed drying process. The drying process of time can avoid the loss of volatile components. If necessary, secondary drying can be carried out to make the moisture meet the requirements. Because the vapor pressure inside the pills is greater than that outside when microwave drying, the pills will expand to a certain extent, which accelerates the dissolution speed of the pills. Generally, the pills will dissolve completely within 1 hour. For example, the dissolution time of Maren pills and Qingshen Xiaofei pills should not exceed 2 hours according to the pharmacopoeia. The finished products dried by microwave will dissolve within 1 hour. The pilot test results show that the finished products sterilized by microwave are compared with the original powder of traditional Chinese medicine. The total number of bacteria decreased by 1 to 2 orders of magnitude, the microwave action time was long and the sterilization effect was good.

Therefore, when microwave drying is used, the drying materials should be processed in order to ensure good drying and sterilization effect. For example, low-power, fast and long-distance drying methods should be used to prevent the bursting of pills and affect their quality. The shelf life of microwave dried pills is more than 1/3 longer than that of traditional pills.

It can be seen that microwave technology used for drying and sterilization of traditional Chinese medicine preparations not only has fast drying speed, high energy utilization rate, good drying and sterilization effect and high quality of finished products, but also can be used for continuous and automatic production with high working efficiency and good production environment, which meets the requirements of GMP and is worthy of popularization and application.