Reducing In-Process Control (IPC) Testing

Reducing In-Process Control (IPC) Testing by the use of Automated Tablet Compression Machines

At Consort Medical, we use compression machines to produce many millions of pharmaceutical grade tablets per year. In order to produce so many tablets we use ‘state of the art’ automated tablet compression machines.

However, tablet compression is not a simple process and there are many variables to control in order to reliably produce a tablet that consistently meets its specification which is tightly controlled via a licensing system through the MHRA (Medicines and Healthcare Regulatory Agency).

Producing 1 billion tablets per year

Compression machines are used across many different industry sectors, not just the pharmaceutical industry. For the pharmaceutical industry there is a wide variety of tablet types, some examples include:

  • Uncoated tablets (immediate release)
  • Film coated tablets (immediate release)
  • Enteric film coated tablets (delayed release until passed through the stomach)
  • Sustained release tablets (delivery dose over a number of hours)
  • Sugar coated tablets
  • Bi-layer tablets

At Consort Medical, we primarily manufacture film coated tablets in caplet form that allow for easier swallowing. These are immediate release formulations with a coloured film coating that helps mask the taste of the uncoated tablet and aids in tablet identifications (in addition to tablet size and markings).

A typical batch size is 1 million tablets in our 24/7 operating HCMF (High Capacity Manufacturing Facility), where we typically produce up to 100 batches per month. This roughly equates to 100 million tablets per month and over 1 billion tablets per year.  To achieve production of this scale, our tablet compression machines follow a strict process to control the many variables.


The Four Steps of Tabletting

A simplified process flow for tabletting is as follows:

  1. Filling
  2. Metering
  3. Compression
  4. Ejection

This process occurs very quickly and utilises top of the range equipment. The tablet compression machines in our HCMF are coupled through a control console to an in-line WHT (Weight, Hardness and Thickness) sampling unit. Uncoated tablet cores are then passed through de-dusters and metal detectors. The compression machines are double sided and operate at up to almost 4000 tablets per minute.

The control console controls both sides of the compression machine and utilises information from the in-line WHT unit along with the compression machine compaction force. This way, the compression machine’s operating parameters are automatically adjusted to meet a pre-set specification.

It was not always like this in the past, IPC tablet tests from weight thickness and hardness were done manually (usually every hour) and the press stopped for adjustment – some companies still use manual IPC tests and readjust compression machines manually. This slowed down the process considerably and was not as efficient. Additionally, the presses needed to be continually monitored and could not be run in ‘light out’ mode.

For automated compression machines to run effectively there are a number or parameters that needed to be controlled to meet the four basic parts of the process.


Filling requires good powder flow – this is achieved at Consort Medical by a granulation process (spray granulation utilising a fluid bed granulator). This is where the API (Active Pharmaceutical Ingredient) are mixed in a fluid bed granulator whilst being sprayed with a granulation liquid to agglomerate the particles of API powder to form larger granules. These granules are dried to a pre-set moisture content under control of air temperature and flow rate. To achieve even more consistency the granules are graded through a mill before being mixed with powdered diluent and lubricant. This is a validated process so that the granule mass / size / moisture content is repeatable between batches and results in consistent flow properties to fill the compression dies quickly to achieve tablet weight control and compression speeds. Granulation also reduces the effect of segregation of API’s due to particle size segregation effects.


Metering requires good flow of granule together with consistent granule density. Variation in granule density and poor flow will result in variation of tablet weight at a set compression speed and would require the compression turret speed to be reduced to maintain tablet weight in specified tolerance.


Compression requires the formulation and manufacturing process of the granule that easily compresses to produce tablets of the required hardness and correct quality with no defects and to meet dissolution requirements.


Ejection requires the formulation and manufacturing process of the granule that easily compresses to produce tablets of the required hardness and correct quality with no defects and to meet dissolution requirements.

Increased efficiency in tablet compression to meet patient supply

All pharmaceutical companies strive for increased productivity consistent with improving quality, and Consort Medical is no different. To achieve this increased production, it requires modern validated automated compression machines linked to automated in-line testing equipment that feeds back in real time to adjust the compression machine’s parameters. This is only possible with a validated formulation and granulation/mixing process in order to reduce variability to a minimum.

The benefits seen are an increase in efficiency in terms of tablet compression speed with reduced level of manual input to produce tablets of improved consistency and quality. The end effect is the production of an increased quantity of high quality tablets that both meet specification and patient supply.


Would you like to know more about this process?

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