The packagings applied for oral safe medicines require the microbial number is within the standard limits. According to Chinese Pharmacopoeia (year 2015, items 1105, 1106), the baisc limits are below.
- Aerobic bacteria <= 100 cfu per unit
- Molds and yeasts <= 10 cfu per unit for sprayer, <= 100 cfu per unit for plastic bottle,
- Staphylococcus areus = 0 cfu per unit
- Pseudomonas aeroginosa = 0 cfu per unit
- Escherichia coli = 0 cfu per unit
The packagings produced in the purification rooms can meet the above limits unless other contamination occurs. If require lower microbial level, additional sterilization is needed. Three main sterilization ways are often used.
Sterilized via vapor. This method is simple and doesn’t need complicated equipment. Pharmaceutical companies can operate in the plant by themselves. However, these method can not be used for PET bottle because PET bottle will deform immediately once it is heated (See Types of Plastic Materials). And vapor can not reach the inner cavity of pump so sterilization is only effective on the surface.
Sterilization via ozone gas. This method can be operated in some packaging manufacturers’ factories. It need build a separated room as the ozone sterilization room, in which ozone gas will be filled. High temperature isn’t applied so PET bottle can be sterilized by ozone. The limit of ozone gas is still sterilization can only be effective on the surface but can not go inside the pump inner cavity. Materials’ resistance ozone refers to “Gaseous Ozone Resistance of Materials“.
Sterilization via irradiation (gamma ray). This method is the best sterilization way. The irradiation ray can penetrate any walls to kill microorganisms in the sealed cavity. General ray dosage is 5 kGy. The whole progress is just a few minutes. The sterilized plastic unit’s microbial level can be close to zero. Packaging manufacturers can not perform irradiation sterilization at the plant by themselves. Irradiation is a very dangerous operation so only professional companies with license can do irradiation sterilization. The packaging are completed and sealed well in the boxes at the packaging manufacturing factories and then are delivered to the professional company for irradiation sterilization. The cost is very cheap. Just need queue so leads to longer lead time. There are two points necessary for irradiation sterilization. Firstly, once sterilization, the outer packaging can not be opened or damaged during the shipment, or the goods will be re-contaminated. Therefore, if the pharmaceutical company can do irradiation sterilization in their own city, better not request the packaging manufacturer to do irradiation sterilization before shipment. Secondly, after irradiation sterilization, the color of plastic will become a little yellow but not obvious. The higher dosage of ray, the more yellowish. However, this yellow doesn’t reduce the quality of plastic unit. Just this point should be known to avoid worry. One important point is that multiple irradiation sterilization of sprayer should be avoided because PP has low toleration of irradiation. Materials’ resistance to irradiation refers to “Irradiation Resistance of Materials“.
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