Andy Tay, PhD is a freelance science writer based in Singapore. He can be reached at andy.csm2012@gmail.com.
An important criterion for drug manufacturing is to ensure product purity and consistency. Ingredients used in making drugs are likely to be heat sensitive and care must be taken to preserve the stability of active therapeutic ingredients while removing impurities, unreacted components, and moisture. Evaporators can help achieve all of these goals. Household Freeze Dryer
There are two main categories of evaporators, tubular or plate-based. The tubular type, such as a thin film evaporator or wiped film evaporator, is one of the most commonly used distillation/evaporation equipment in the pharmaceutical industry. In this machine, samples are introduced at the top of the evaporator above the heated zone and evenly distributed down the vessel wall in a turbulent flow. This flow creates optimum heat transfer to evaporate volatile compounds and concentrate samples at the discharge outlet.
In a thin film evaporator, samples have short residence time in the tubular vessels, which enhances the throughput of processing, a key consideration for large-scale manufacturing. With high turbulence flow, there is also fast heat transfer to concentrate samples and remove impurities. Finally, because the rotor blade is continuously rotating and the sides of vessel walls are being “wetted” by steam, it reduces the contact time between samples and vessel walls and minimizes biofouling.
Evaporators can be used to concentrate active pharmaceutical ingredients while protecting their stability and biofunctions and distilling organic solvents from temperature sensitive products. In some cases, evaporators can also help remove excess water to completely dry products to extend shelf-life and remove impurities down to safe-to-use or -consume levels. With these, pharmaceutical companies can manufacture products with high quality and consistency.
When chosen and used correctly, evaporators can significantly improve sample purity, quality, and consistency.
Before deciding on an evaporator model, there are some critical factors to consider. First is the evaporator’s materials. Common materials used in evaporators are stainless steel and graphite. Evaporation takes place at high temperatures and the equipment needs to withstand heat, plus chemical corrosion from acids and solvents. Additionally, the material of the evaporator should not react with samples to avoid biofouling and introducing impurities to the samples.
Second is throughput or volume of the evaporator. There are evaporator models offering various rates of sample volume processing and depending on the applications, different models are more suitable. For instance, for a drug with huge and steady consumer demand or a significant volume of solvent or moisture to evaporate, a high-throughput evaporator is helpful. For a niche drug that has lower sales volume, a smaller evaporator might suffice.
Third is user control. In older models, the user interface does not reflect the rate of heating and/or temperature change, but in newer models, this information is digitally monitored and reflected and users can even be alerted to unusual fluctuations during sample evaporation. This can be helpful to ensure batch-to-batch consistency in drug production. This is because the presence of dissolved solids like salts in samples are known to raise the boiling point of samples, which may degrade active pharmaceutical ingredients.
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