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How to help prevent tablet punch sticking in pharmaceutical manufacturing
In this Leaders in Pharma Spotlight, Samer Al Halabi, pharmaceutical application specialist based in our Solution Center in Essen, Germany, unveils solutions to help pharmaceutical manufacturers overcome challenges presented by punch sticking in the direct compression tablet manufacturing process.
Decoding punch tablet sticking: Navigating the core challenges
Tablets are the most widespread and popular dosage forms for medical applications, making the science and precision of tablet manufacturing pivotal for the pharmaceutical industry. Among the myriad of challenges producers encounter in the tableting process, punch tablet sticking is one of the most common. It can create significant hurdles in pharmaceutical ingredient quality and manufacturing efficiency.
What is punch sticking in tableting?
Tablet sticking refers to the phenomenon in which a tablet's ingredients adhere to the punch and die rather than being ejected cleanly. Punch tablet sticking can lead to difficulties in ejection, tablet damage, and overall quality degradation. This tablet manufacturing flaw compromises the tablet's quality and reduces manufacturing efficiency, necessitating frequent tooling and punch surface cleaning.
This comprehensive exploration delves into the nuances behind tablet punch sticking causes, shedding light on its causes and unveiling targeted solutions to mitigate its impact.
Decoding punch tablet sticking: Navigating the core challenges
Tablets are the most widespread and popular dosage forms for medical applications, making the science and precision of tablet manufacturing pivotal for the pharmaceutical industry. Among the myriad of challenges producers encounter in the tableting process, punch tablet sticking is one of the most common. It can create significant hurdles in pharmaceutical ingredient quality and manufacturing efficiency.
What is punch sticking in tableting?
Tablet sticking refers to the phenomenon in which a tablet's ingredients adhere to the punch and die rather than being ejected cleanly. Punch tablet sticking can lead to difficulties in ejection, tablet damage, and overall quality degradation. This tablet manufacturing flaw compromises the tablet's quality and reduces manufacturing efficiency, necessitating frequent tooling and punch surface cleaning.
This comprehensive exploration delves into the nuances behind tablet punch sticking causes, shedding light on its causes and unveiling targeted solutions to mitigate its impact.
Solutions to help avoid tablet punch sticking
Lubricants: Essential yet tricky
In the tablet manufacturing process, lubricants form a layer around powders and granules which reduces friction between the tablet itself and machine tools, such as the punch tip or the dye wall. However, the efficacy of lubricants can cause sticking-related issues due to a variety of primary causes explored below. Here are some insights to help overcome tablet punch sticking challenges when using lubricants:
- Ensure you have selected the optimal concentration of the lubricant
- Allow for homogeneous mixing and sufficient sieving with the other components of the tablet to increase the effect of the lubricant
- Introduce lubricants to the formulation at the proper stage in the process; Lubricants should only be added during the final blending stage in order to significantly reduce sticking occurrences
- It is essential that no additional excipients are added after lubricants have been blended into the formulation
Moisture dynamics and melting mishaps
Moisture content – as well as contact melting – can lead to sticking issues in tablet production. Together, we can explore strategies to navigate and manage these challenges for smoother manufacturing by:
- Aiming to select excipients, binders, and fillers with lower moisture content
- Avoiding using hygroscopic tableting ingredients that absorb moisture from the environment
- Helping to ensure strict control of humidity during the handling and compression of the tableting ingredients
Also, avoid using ingredients with a low melting point as they can cause the tablet to melt at the punch surface while under pressure. Suitable excipients that can help with this issue include colloidal silica or microcrystalline cellulose.
Moisture dynamics and melting mishaps
Moisture content – as well as contact melting – can lead to sticking issues in tablet production. Together, we can explore strategies to navigate and manage these challenges for smoother manufacturing by:
- Aiming to select excipients, binders, and fillers with lower moisture content
- Avoiding using hygroscopic tableting ingredients that absorb moisture from the environment
- Helping to ensure strict control of humidity during the handling and compression of the tableting ingredients
Also, avoid using ingredients with a low melting point as they can cause the tablet to melt at the punch surface while under pressure. Suitable excipients that can help with this issue include colloidal silica or microcrystalline cellulose.
Active pharmaceutical ingredient (API) properties
API properties, such as high surface area, surface energy, and particle size, can predispose formulations and contribute significantly to manufacturing challenges and final dose quality. By exploring and addressing some of these elements, producers can overcome these issues:
- Choosing the most compactable system can help to mitigate and manage the properties of a solid dosage form
- Using APIs with reduced surface area and low surface energy reduces the opportunity for sticking
- Exploring the components of the tableting ingredients and choosing APIs with the most compatible particle size; Larger particle size and shape distribution often helps
Powder dilemmas
The ratio of fine powder and poor powder characteristics, such as deficient flowability and broad particle size distribution, can also play an essential role in product formulations.
- Tableting ingredients with a high percentage of fine powder tends to adhere to the punches; Be sure to sieve the granules properly to generate less fine powder
- Increasing machine pressure can help force the powder to adhere to the tablet surface instead of the punch surface
- Reduce attrition, or the breakage of particles, during dry granulation by roller compaction
- Add a glidant to improve the powder flowability
- Avoid broad particle size distribution among the components of the tablet and improve powder compaction
Powder dilemmas
The ratio of fine powder and poor powder characteristics, such as deficient flowability and broad particle size distribution, can also play an essential role in product formulations.
- Tableting ingredients with a high percentage of fine powder tends to adhere to the punches; Be sure to sieve the granules properly to generate less fine powder
- Increasing machine pressure can help force the powder to adhere to the tablet surface instead of the punch surface
- Reduce attrition, or the breakage of particles, during dry granulation by roller compaction
- Add a glidant to improve the powder flowability
- Avoid broad particle size distribution among the components of the tablet and improve powder compaction
Case hardening
Through the wet granulation process, large lumps in the formulation can also cause punch sticking during compression.
- Avoid the manual addition of binder solutions, as well as rapid drying procedures
- Ensure your selected chopper and wet mill are working correctly so that large lumps are broken down within the formulation and your mixture has smooth flowability and particle size distribution
Environmental factors: Relative humidity and temperature considerations
High relative humidity in the compression area results in sticking during compression. Additionally, high temperatures may cause the melting of macrogol or magnesium stearate in formulations. Therefore, producers are encouraged to explore the tactics below to produce optimal results:
- Control the humidity level of the compression area using a heating, ventilation, and air conditioning system (HVAC)
- Maintain strict control of the temperature by the HVAC system
- Place silica desiccants in any final blended product containers
Environmental factors: Relative humidity and temperature considerations
High relative humidity in the compression area results in sticking during compression. Additionally, high temperatures may cause the melting of macrogol or magnesium stearate in formulations. Therefore, producers are encouraged to explore the tactics below to produce optimal results:
- Control the humidity level of the compression area using a heating, ventilation, and air conditioning system (HVAC)
- Maintain strict control of the temperature by the HVAC system
- Place silica desiccants in any final blended product containers
Compression (tableting) machine factors: Insufficient compression force
To avoid punch sticking in your mass production tableting process, it is essential to use the proper compression force in the powder compaction. Pre-compression and dwell time are two crucial elements that should be considered to help ensure smooth tablet manufacturing.
- Pre-compression is the stage where a small force is applied to the powder bed to form partial compacts prior to undergoing main compression. The pre-compression roller is usually smaller in size than the main compression roller
- In tableting, dwell time is the time each individual punch head flat remains in contact with the compression roller. Increasing dwell time helps to ensure sufficient compression force. To increase dwell time, pre-compression can be employed, or the speed of the tablet machine can be reduced
Machine punch condition and tooling properties
The condition of the machine punch and machine tooling properties reveal some areas of concern in tableting. Here are some important solutions to ensure you have the right setup for optimal quality, effectiveness, and precision in tableting:
- The punch tip is a chrome surface that can become rough over time and impact machine performance and the quality of the output; be sure to polish the punch tip with appropriate polishing materials regularly
- Use chromium nitride-coated punch tips, which exhibit excellent anti-sticking properties
When embossing the punch tip, avoid using deep or close letters or intricate logos that might enhance sticking - Clean punches and dyes thoroughly, removing any tableting material residue once the tooling is removed from the tablet press
- Protect tooling from deleterious conditions such as corrosion (oxidation) during storage
- Use punches with a modified surface, such as chromium electroplating, that protects the punch surface against corrosion
- Replace dyes consistently as needed
Machine punch condition and tooling properties
The condition of the machine punch and machine tooling properties reveal some areas of concern in tableting. Here are some important solutions to ensure you have the right setup for optimal quality, effectiveness, and precision in tableting:
- The punch tip is a chrome surface that can become rough over time and impact machine performance and the quality of the output; be sure to polish the punch tip with appropriate polishing materials regularly
- Use chromium nitride-coated punch tips, which exhibit excellent anti-sticking properties
When embossing the punch tip, avoid using deep or close letters or intricate logos that might enhance sticking - Clean punches and dyes thoroughly, removing any tableting material residue once the tooling is removed from the tablet press
- Protect tooling from deleterious conditions such as corrosion (oxidation) during storage
- Use punches with a modified surface, such as chromium electroplating, that protects the punch surface against corrosion
- Replace dyes consistently as needed
Overcoming punch tablet sticking challenges in pharmaceutical manufacturing
Tablet punch sticking is more than a mere inconvenience – it’s a complex problem that can quickly lead to production inefficiencies and compromised quality. Resolving the issue begins with a thorough understanding of its multifaceted causes.
Everything from the importance of optimal lubricant concentration and homogeneous mixing to moisture dynamics, melting mishaps, and API properties can contribute. Additionally, environmental factors, machinery, and tooling play an important role.
By understanding and addressing these factors, manufacturers can significantly reduce sticking occurrences, enhance the quality and efficiency of tablet production, and help ensure successful pharmaceutical tableting with your products.
Are you seeking innovative methods to enhance your tableting processes to avoid punch sticking? Connect with our in-house pharma lab services experts in our Global Solution Centers to help overcome your tableting or pharmaceutical formulation challenges.
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Author Bio
Samer Al Halabi
Pharmaceutical application specialist
Univar Solutions Global Solution Center, Essen, Germany
At Univar Solutions, Samer provides in-depth technical support for customers and suppliers with a focus on pharmaceutical and nutraceutical formulations and new product development. Samer leads the company’s pharmaceutical ingredients lab in Essen where he ensures the lab offers state-of-the-art equipment and capabilities while also supporting customers on-site at their pharmaceutical manufacturing facilities to troubleshoot challenges and deliver solutions.
With over 15 years of experience in research and development, production, and quality across pharmaceutical, food, and personal care industries, Samer is passionate about delivering innovative and customized solutions for customers. He holds a bachelor of science degree in pharmacy, as well as a master’s degree in analytical toxicology, both from The University of Jordan.
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