Filtration in Pharmaceutical Industry

Filtration removes solid particles from the liquid or gaseous state of Pharma products, that are have become infected with any contaminants. If filtration is not applied, it will affect the pharma process and the final product will become hazardous for human consumption. 

The type of products that can be subject to filtration are various such as raw material, final finished product, and intermediate form of product. Some test samples used in the QC laboratory also require filtration. For specific filtration requirement, regulatory guidelines should be consulted for developing filtration strategy for a given product.

Mainly, filtration is a process that is applied as a part of a contamination control strategy for removing impurities, controlling contamination, and improving product quality. Without filtration, it is impossible to implement contamination control strategies across many pharmaceutical processes. 

Different types of methods and equipment for filtration in the pharmaceutical industry exist. It depends upon the type of product, active contamination, and degree of purification required for implementing the filtration method.

Filtration methods

Let's discuss some filtration methods employed in the pharmaceutical industry.

Surface filtration

Surface filtration is the most common method in the pharmaceutical industry. In this method, impurities remain on the surface of filter media as a pharma product. 

In this method, as the contaminants build up on the surface of filter media, flow decreases due to the resistance offered by the impurities. When a maximum quantity of material builds up, the surface must be cleaned to allow efficient filtration and to operate the filter equipment as per its standard speed.

During changing filter or maintenance activity, the equipment or system must be stopped and cannot be performed during equipment operation.

The filter size depends upon the filtration requirement, i.e., particle size and the speed of filtration equipment. 

Membrane-based filtration systems are examples of surface filtration systems.

Depth filtration

Depth filtration is a specialized mechanism where material (to be filtered) flows downward. It is mainly used for soluble materials and suspended particles that cannot be dissolved in liquid substances. 

The depth filtration system employs a wise stage mechanism, where large particles are removed at the initial stage and smaller-sized impurities are removed later.  

The action of backflow in the material cleans filters. The material (to be filtered) flows in opposite directions, i.e., from product outfeed to product infeed. This enables the impurities retained on the filter surface to leave, causing the blocked pores to open. The deposited impurities are collected through discharge or reject output.

Compared to surface filtration, depth filtration equipment are expensive. However, its high price is compensated by the extended life of the operation.

Cross flow filtration

Cross filtration includes a filtration membrane that can filter impurities of sizes in the range of nanometers or below.

These types are typically used to filter out total dissolved substances.

Since the pores of the nanometer membrane are small, the filtration membrane can be affected by fouling and scaling. This can significantly decrease the filtration efficiency, so these filters require constant maintenance and inspection. 

Ultrafiltration

Ultrafiltration filters out ultra-small substances, typically less than 0.01 microns. This filtration is specifically designed to filter out extremely small particles. Ultrafiltration is commonly employed at the last stage when the material has been filtered with all the large-sized impurities. 

In addition to particles and impurities, ultrafiltration can remove microorganisms and bacteria.

A semipermeable membrane is often used as the filtration media in ultrafiltration. In this type, the material (to be filtered) is made to flow through a membrane with high pressure to work, to overcome the osmotic pressure associated with a semipermeable membrane. 

Filtration equipment

Filtration in the Pharmaceutical process is implemented through filtration equipment installed at the desired process location. Let's discuss some common filtration equipment in the pharmaceutical industry.

Dust collectors

Does the collector are used to collect dust particles from the area, equipment, or Pharma processes? The filter inside the dust collector separates the solid particle from the incoming air. The solid particles are collected on the filter and clean the air. The purified air then leaves the dust collector and is typically returned to the production area through the air handling system.

Dust Collector can filter out solid particles typically in the range of sub-micron level. Various types of filters are available, depending on the type of product and process requirement.

The collected particles in the dust collector can then be removed from the filter or separated in the collection unit. 

In the pharma industry, dust collectors are commonly used in areas that generate high concentrations of dust particles, such as in the tableting department, granulation, and oral filling section.

Sterile filtration

Sterile filtration filters out impurities and contaminants from products that cannot be terminally sterilized. Terminal sterilization is executed to kill microorganisms and contamination from Pharma products through high temperatures for some products. Sterilization is not feasible; it changes the chemical properties or degrades the pharma product.

Sterile filtration equipment consists of a filter having a 0.2-micron capacity. The filter with this capacity can provide the sterility assurance level required for sterile products.

Filters for sterile filtration require frequent integrity testing. Its basic purpose is to ensure and prove that the filter in the housing is free from any leak and is not damaged. Additionally, there is no change in its physical appearance.

HEPA filters

HEPA stands for "High-Efficiency Particulate Air" and can purify 99.97% of air by removing dust, microorganism, and solid particles as small as 0.3 microns.

HEPA filters are used in the pharmaceutical industry for critical areas such as parental product manufacturing. They are mostly installed as a final stage filter in an air handling unit.

HEPA filters are combined with other filter types to remove solid particles of large sizes. Pre-filters remove large particles, and HEPA filters can filter out small particles. If pre-filters are not used, the large-sized particle will damage the HEPA filter. As a result, the efficiency and life of HEPA filters will decrease and increase the maintenance frequency.

HEPA filters are made up of micro glass fiber, synthetic fiber, or polytetrafluoroethylene PTFE that are pleated with each other. The pleated pattern leaves no space in the housing for air leakage. This enables air velocity to pass through it without damaging the HEPA filter or escaping sideways through the housing.

Bag filters

Bag filters consist of a bag of filtering material, commonly cotton or Wool fiber. They are used to collect suspended particles in the air that are large.

A motor-driven blower creates a vacuum across it, effectively forcing the air to press across the filter's bag filter. When air passes through the bag filter, particles are collected at the filter surface. It used surface filtration, where particles build up on the surface of the bag filter as air passes through it.

Bag filters are also provided with a shaking mechanism, which shakes the bag filter intermittently or after a fixed time. Its main purpose is to remove the particles from the bag filter. The shredded particles are collected at the base of the filter, which can be cleaned or removed when it exceeds its limit.

Filters can be used solely in the equipment or combination with other filters.

When you solely, they only filter out large-sized particles. This combination is used for the pharma process, where requirements are less stringent and for less critical products and processes.

Combined with other filters, its main purpose is to filter out incoming high-volume particles to prevent damage from large-size particles. An example is the Air Handling Unit, where the Bag filter is used to finish the incoming air for the final stage HEPA filter so that HEPA filters are not affected by large-sized particles.

Pharma processes requiring filtration

Let's discuss some pharmaceutical departments where filtration is employed and used.

Tablet press machine

A tablet machine is used to form tablets from granules. At presides the granules and high pressure converts the granules into tablet form.

An area where the tablet machine installs fine granules of powder of an escape in the air from the upper during machine run product transfer.

Particles are easy to enable by the person working in the area, which is harmful to them.

Filtration is used in tablets with a machine to collect the particles and topper and Ham to the personnel.

Granulation

In the Granulation area, a fluid bed dryer is used to draw the mixture of chemical composition products. Everybody away filled is installed above the product container to prevent the product the machine through the exhaust.

Bike filters are slowly designed to capture Lal size particles. In a BD, the product's size also has large back filters that can effectively prevent the product by utilizing the filtration method.

Clean rooms

Clean rooms are specially designed area that provides a special product-specific non-mended condition that suggests temperature, humidity, and airflow, including filtered clean air.

The cleaner is also a feature that clean rooms are required to supply.

For Clean air, clean rooms are provided with HEPA filters. The airflow in the clean room passes through the hero filter that effectively filters round the incoming air from fine particle sizes.

About the Author

Muhammad Asim Niazi has a vast experience of about 11 years in a Pharmaceutical company. During his tenure he worked in their different departments and had been part of many initiatives within the company. He now uses his experience and skill to write interested content for audiences at PharmaSources.com.