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2022-09-21
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Drug transportation - thermodynamic packaging (Part 1)

recently, such a thing happened in Canada. Some patients died after using the correct dose of vaccinia vaccine, because the drugs in the bottle crystallized in the severe winter

this kind of medicine is transported in a box insulated with foam plastic. The drugs leave the factory in Puerto Rico and are transported to San Juan Airport by ground transportation. After being stored there for a period of time, the drugs are loaded by transport aircraft and then transported to a distribution point in Canada. The pharmaceutical factory carefully transports them in large packages, and the distribution point repacks them in small packages and distributes them to various clinics. From the pharmaceutical factory to the final destination, through ground transportation and air transportation, there are several storage stages, and the drugs should be exposed to the following environment:

in Puerto Rico, the temperature is 32~35 ℃, and the humidity is 90%

in the conveyor, the height is 35000 feet, and the temperature is about -6 ℃

at the final destination, the temperature is below zero

extreme climatic conditions play a role inside and outside the transport box. When the warm, humid and low-pressure system meets the cool and dry air, the air can't stand the humidity, and dew will form here. In order to avoid the bad temperature of drugs, it is most important to choose the appropriate packaging materials and packaging design

sensitivity to temperature

in recent years, the use of temperature recorders and temperature indicators in the transportation of drugs has proved that drugs have indeed experienced a harsh temperature environment during transportation, but the information available to pharmaceutical manufacturers is incomplete. A variety of temperature recorders are transported with large packages, but the results are contradictory. The temperature recorder reflects that it has experienced bad temperature, but because it cannot provide a record file of the relationship between time and temperature, its use in pharmaceutical factories is limited

out of vigilance against bad temperatures, some pharmaceutical companies have become very cautious and even destroyed drugs that are only suspected to have experienced bad temperatures. Of course, this will increase costs. Some pharmaceutical factories and biological companies are focusing on developing and reducing their reliance on landfills for biologically active drug packaging, which requires strict temperature conditions. The temperature range of drugs is different. Some may need to be preserved in the domestic in mold labeling packaging market that has been covered by solid ice for many years at room temperature for nearly two years (13 ~ 29 ℃). Some need to be refrigerated but cannot be frozen, which will almost affect the service life of the device. All drugs will decompose at high temperature (≥ 40 ℃), and all biological drugs will fail below the freezing point or when they deviate from room temperature. Some substances will freeze immediately below 0 ℃, but water is not like this. The surface of water below zero must be fully exposed before freezing. Therefore, the physical properties of some drugs do not change immediately upon exposure, but are related to time temperature, and the dynamic properties vary according to the material. Most biological drugs are safe at 2 ℃ ~8 ℃, and physical changes will occur only after exposure outside this range for a long enough time. Because some drugs contain water in addition to other substances in this range, they will not freeze until they are exposed below zero for 6~8 hours

state change materials

when researchers discuss temperature measurement, the most frequently cited is water. For example, water begins to become solid at zero (freezing point), and water begins to vaporize at 100 ℃, which is usually called boiling point. With the change of temperature, water changes from liquid to solid or vapor, which is called phase transition, that is, state change. For packaging that needs temperature control, phase transition is of great significance. Consider a container containing ice. When it is heated continuously, its temperature rises rapidly before reaching the melting point of ice. The energy required for ice to change from a solid state to a liquid state is called heat capacity, which remains constant until the ice is completely dissolved. The characteristics of water absorbing a lot of heat and keeping the temperature constant provide the basis for many packaging methods that need to control the temperature. It is important to remember that the temperature of substances is constant during phase transition. When ice turns into water, the temperature of ice is zero, and when water vaporizes, the temperature of boiling water is 100 ℃. For packaging, the phase transition of substances can be used to maintain the temperature of adjacent products through heat transfer (heat convection, heat conduction and heat radiation). The longer the phase change process takes, the longer the phase change material will maintain a constant temperature

all substances have transition points, and the temperatures are different. Some substances can be combined to get a material, and its state is within a certain temperature range. If a material becomes solid at -50 ℃, any product placed in this package can be well preserved below zero, which is related to the time required for state change and the design of the package. The same is true at high temperatures. Now the state of the material can be solidified or dissolved at low or high temperature. When used in packaging, its composition can be kept unchanged at -50 ℃ ~40 ℃, and the state transition of materials can eliminate dry ice by keeping low temperature. Other state transition materials can be kept at room temperature or higher, and if the overload or unloading angle is too large, it has nothing to do with the external temperature. As the high-temperature state transition material may regenerate itself, the state transition is continuous, and manual refrigeration and heating are no longer required to maintain the controlled temperature. (to be continued)

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