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How to help prevent tablet punch sticking in pharmaceutical manufacturing
In this Leaders in Pharma Spotlight, Samer Al Halabi, senior 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.
Solving tablet punch sticking for smoother, more reliable manufacturing
Tablets are the most widespread and popular dosage form in medicine, making precise manufacturing essential for quality and efficiency. Among the many challenges in tableting, tablet sticking in pharmaceutical manufacturing is one of the most common, causing defects and slowing production. Because sticking often stems from formulation behavior and ingredient interactions, solving it requires more than compression adjustments.
Solving tablet punch sticking for smoother, more reliable manufacturing
Tablets are the most widespread and popular dosage form in medicine, making precise manufacturing essential for quality and efficiency. Among the many challenges in tableting, tablet sticking in pharmaceutical manufacturing is one of the most common, causing defects and slowing production. Because sticking often stems from formulation behavior and ingredient interactions, solving it requires more than compression adjustments.
Ingredients + Specialties from Univar Solution’s partners with many of the world’s top pharmaceutical manufacturers on everything from ingredient formulation to process hurdles. Our technical experts help pinpoint root cause and recommend targeted ingredient and process solutions to improve tablet consistency.
Ready to eliminate punch sticking now?
Our pharmaceutical formulation experts can help you pinpoint the cause and tailor ingredient and process solutions to your specific tablet line.
What is punch sticking in pharmaceutical tableting?
Tablet sticking occurs when tablet ingredients adhere to the punch and die rather than being ejected cleanly. Even small amounts can cause issues during production, including:
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Damage to tablets
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Inconsistent tablet quality
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Decreased output and efficiency
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Frequent tooling and punch surface cleaning
Understanding the “why” is the first step in eliminating the punch sticking problem. In this comprehensive exploration, we will delve into the nuances behind tablet punch sticking, shedding light on its root causes, and unveiling targeted solutions to help you mitigate its impact.
What is punch sticking in pharmaceutical tableting?
Tablet sticking occurs when tablet ingredients adhere to the punch and die rather than being ejected cleanly. Even small amounts can cause issues during production, including:
-
Damage to tablets
-
Inconsistent tablet quality
-
Decreased output and efficiency
-
Frequent tooling and punch surface cleaning
Understanding the “why” is the first step in eliminating the punch sticking problem. In this comprehensive exploration, we will delve into the nuances behind tablet punch sticking, shedding light on its root causes, and unveiling targeted solutions to help you mitigate its impact.
Solutions to help avoid tablet punch sticking
Lubricants: Essential yet tricky
In the manufacturing process, lubricants form a layer around powders and granules, reducing friction between the tablet itself and machine tools, such as the punch tip or die wall. However, the efficacy of lubricants can cause sticking-related issues. To get the most out of your lubricants:
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Ensure you have selected the optimal concentration of the lubricant
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Mix thoroughly and sieve sufficiently with other tablet components to increase effectiveness
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Introduce lubricants only during the final blending stage
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Avoid adding any new excipients after lubrication
Moisture dynamics and melting mishaps
Moisture content and contact melting can lead to sticking issues in tablet production. To control moisture-related sticking:
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Choose excipients, binders, and fillers with lower moisture content
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Avoiding hygroscopic tableting ingredients that absorb moisture from the environment
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Maintain strict control of humidity during the handling and compression of the tableting ingredients
Additionally, avoid using ingredients with a low melting point, as they can cause the tablet to melt at the punch surface while under pressure. Excipients like colloidal silica or microcrystalline cellulose can help stabilize the compression process.
Moisture dynamics and melting mishaps
Moisture content and contact melting can lead to sticking issues in tablet production. To control moisture-related sticking:
-
Choose excipients, binders, and fillers with lower moisture content
-
Avoiding hygroscopic tableting ingredients that absorb moisture from the environment
-
Maintain strict control of humidity during the handling and compression of the tableting ingredients
Additionally, avoid using ingredients with a low melting point, as they can cause the tablet to melt at the punch surface while under pressure. Excipients like colloidal silica or microcrystalline cellulose can help stabilize the compression process.
Active pharmaceutical ingredient (API) properties
Your API’s properties, such as high surface area, surface energy, and particle size, can predispose formulations and contribute significantly to manufacturing challenges and final dose quality. To minimize sticking:
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Choose compactable systems that support your formulation design
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Use APIs with reduced surface area and low surface energy
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Exploring the components of the tableting ingredients and choosing APIs with the most compatible particle size; a larger particle size often sticks less
Powder flow and particle size challenges
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 flow and particle size challenges
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 cause punch sticking during compression. Avoid these issues by:
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Skipping the manual addition of binder solutions
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Avoid rapid drying procedures
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Ensure your 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. To create a stable environment for your compression area:
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Use an air conditioning system (HVAC) to control the humidity of the compression area
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Have proper ventilation
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Maintain strict and consistent control of the temperature by the HVAC system
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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. To create a stable environment for your compression area:
-
Use an air conditioning system (HVAC) to control the humidity of the compression area
-
Have proper ventilation
-
Maintain strict and consistent control of the temperature by the HVAC system
-
Place silica desiccants in any final blended product containers
Tableting machine factors: compression force and dwell time
Insufficient compression force is a common cause of sticking. To avoid punch sticking, increasing dwell time or optimizing pre-compression often results in cleaner ejections with fewer defects. Two machine steps can mitigate punch sticking:
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Pre-compression: a small initial force is applied to the powder bed to form partial compacts before undergoing main compression.
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Dwell time: the amount of time each punch head flat remains in contact with the compression roller. Increasing dwell time helps to ensure sufficient compression force.
Machine punch condition and tooling properties
The condition of the machine punch and machine tooling properties can affect tablet quality and production. To ensure you have the right setup for optimal quality, effectiveness, and precision in tableting, our specialist recommend:
- 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
- Avoid using deep, close letters or intricate logos on punch tip embossing
- Clean punches and dies thoroughly and routinely
- 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 dies consistently as needed
Machine punch condition and tooling properties
The condition of the machine punch and machine tooling properties can affect tablet quality and production. To ensure you have the right setup for optimal quality, effectiveness, and precision in tableting, our specialist recommend:
- 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
- Avoid using deep, close letters or intricate logos on punch tip embossing
- Clean punches and dies thoroughly and routinely
- 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 dies consistently as needed
Overcoming punch tablets sticking challenges in pharmaceutical manufacturing
Tablet punch sticking is more than a mere inconvenience; it’s a complex problem that impacts production quality and efficiency. 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.
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Let's get started on your next pharmaceutical innovation
Discover how our technical specialists can help you select the right ingredients to help you achieve the most stable and desired tablet formulation.
Author Bio
Samer Al Halabi
Senior 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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