The Advantages Of Wet Milling In The Pharmaceutical Industry

Wet milling is a process defined as the size reduction of wet granulation prior to a fluid bed dryer. This has huge implications for the pharmaceutical industry in particular. Typical reasons for wet milling include reducing fluid bed drying time, improving moisture uniformity across a dried product, and improving material throughput during dry milling. This article will take a brief look at the vast benefits of wet milling in the pharmaceutical industry.

To begin, a major concern is safety. Companies need to be cognizant of their employees' health. By employing a wet milling technique, occupational exposure to dust fines is greatly reduced. This also minimizes the number of product handling situations a worker could be exposed to. With a reduction in fines generation not only is the workers safety increased, but the amount of product waste is also greatly reduced.

When it comes to particle reduction of compounds with high potency or high dust explosivity rating, high shear wet milling may be the most effective process solution. When it comes to reducing the particle size in your active pharmaceutical ingredients (API) you can add the high shear mixers into the last step of the final crystallization process. This is a more efficient alternative to dry milling. The process involves the use of high-speed rotor blades to exert suction and draw the liquid and solid components into its own separate parts. From a technical standpoint, it's crucial to understand these differences to make sure that each step of development is working as smoothly as possible.

With this in mind, there is new technology that uses wet milling downstream to a crystallization process that efficiently reduces crystal size and produces a narrow particle size ideal for various pharmaceutical products. When designing a new product of small molecule drugs for development and manufacturing, wet milling can be utilized from the pilot phase all the way to the final production steps.

In a case study data presentation at the American Association of Pharmaceutical Scientists (AAPS) in Toronto, 2002, several key findings were found regarding wet milling. It was found that granules appear to break via fragmentation in wet state and via impact attrition in dry state. After dry milling, wet milled materials had less fines compared to material that was not wet milled. Wet milling did not negatively impact granule porosity, drug assay distribution or compactability. It was also found that wet milling reduced product drying time by 20 - 25%.

There are a number of key benefits associated with wet dispersion prior to product drying. One benefit is that mixing and granulation can form lumps of irregular shapes and size - unless the product is wet milled beforehand. Another benefit is to create homogenous and uniformly sized wet particles for drying. This eliminates moist centers, hard over dried particles from extended drying and reduces drying time significantly.

As you can see, whether the concern is safety or the efficiency of your business, wet milling is something worth considering. Although not all of the pertinent benefits may be well known, it is in the best interest of pharmaceutical companies to weigh out the functionality of all alternatives before settling with an outdated technology. Wet milling provides cutting edge processing solutions to many industries.