Achieving Tablet Stability with Moisture Management
March 25, 2019
Moisture management is a critical aspect of pharmaceutical manufacturing, especially when it comes to tablets. One of the biggest challenges is the impact of environmental moisture on active pharmaceutical ingredients (APIs) and the risk it poses to product stability.
The total moisture content of pharmaceutical products typically includes both bound water and free water. While bound water is harmless, free water is responsible for degrading moisture-sensitive materials, which can result in poor drug stability profiles.
To assess the potential stability of moisture-sensitive products, total moisture content (loss on drying or LOD) is often used. However, this measure alone may not provide enough information to determine the stability of the product. Therefore, it is essential to understand the impact of moisture on drug stability and take necessary measures to manage it.
Moisture Management: Physical Packaging
One of the primary methods for combatting environmental moisture is physical packaging containing low permeability moisture barrier materials and desiccants. Packaging-based solutions can be very successful to maintain potency, stability, and shelf life, and pharmaceuticals and healthcare products often include highly protective and active packaging, but additional physical barrier solutions can add complexity.
For the best solution, manufacturers can incorporate multiple layers of moisture protection into the dosage form design, including the packaging. By doing so, they can reduce moisture-induced degradation and improve drug stability profiles without adding significant costs.
Building Moisture Protection into Dosage Form Design
Understanding good and bad moisture in tablets is essential for managing moisture content in pharmaceuticals. Total moisture content (loss on drying or LOD) is often used to assess the potential stability of moisture-sensitive products. However, the total moisture content of pharmaceutical products typically includes both bound (i.e., water of hydration, linked by hydrogen bonding or entrapped into an amorphous structure) and free water.
To better manage moisture content, manufacturers should focus on reducing water activity within the formulation and retarding interaction with the moisture-sensitive API. This can be achieved through formulation improvements that enhance stability and reduce costs. For example, manufacturers can use Starch 1500®, a partially pregelatinized starch, to scavenge moisture within the formulation and inhibit water activity.
By inhibiting water activity within the formulation, Starch 1500 helps to reduce or eliminate the detrimental effects of other excipients.
Lowering Water Activity to Improve Core Stability
Starch 1500 has a relatively high moisture content, but it has very low water activity. This makes it an excellent excipient to enhance stability and reduce the impact of moisture on APIs. The moisture scavenging properties of Starch 1500 allow it to bond with water molecules within its amorphous structure, inhibiting water activity and reducing interaction with the moisture-sensitive API.
Incorporating Starch 1500 into the formulation can
- Lower the water activity of the core
- Enhance core stability
- Reduce the risk of moisture-induced degradation
By inhibiting the interaction between water and the moisture-sensitive API, manufacturers can improve the overall stability profile of the drug product.
The Role of Film Coating in Moisture Protection
Film coating can be an effective way to protect pharmaceuticals from moisture, provided the formulation is developed with minimal ingress of water and protection from humidity. Recent studies have compared uncoated and coated placebos for film coating moisture barrier properties, using dynamic vapor sorption (DVS) models to measure water sorption.
These studies have found that coated tablets show significantly lower water vapor transmission rate (WVTR) values than uncoated tablets, indicating that film coatings can provide effective moisture protection.
Polyvinyl alcohol (PVA) is a film-forming polymer that has been shown to offer vast improvements in moisture barrier properties over traditional hydroxypropyl methylcellulose (HPMC)-based coatings. PVA-based coatings can help manufacturers reduce the risk of moisture-induced degradation and improve overall stability profiles.
By selecting the right excipients and coatings, manufacturers can build multiple layers of moisture protection into the dosage form design, reducing the need for costly physical barriers and improving drug stability profiles.
Moisture Protection In-Use: A Case Study
To evaluate the impact of film coatings on tablet stability and integrity, a study was conducted on amoxicillin/clavulanic acid dosage forms. The study compared the in-use stability of uncoated, HPMC-based coated, and Opadry® amb II, High Performance Moisture Barrier Film Coating, (PVA) coated tablets following removal from primary packaging at daily intervals for 10 days.
At the end of the 10-day dosage regimen, the uncoated and HPMC-coated tablets showed complete depletion of clavulanic acid, whereas the tablets coated with PVA-based coating, Opadry amb II, maintained acceptable levels of both clavulanic acid and amoxicillin even outside of the primary packaging.
These results confirm that Opadry amb II can protect the integrity of moisture-sensitive compounds beyond the primary packaging. By selecting the right film coating, manufacturers can significantly reduce the risk of moisture-induced degradation and improve the overall stability profile of the drug product.
Protect Your Drug Products from Moisture-Induced Degradation
If you are a pharmaceutical company concerned about the moisture content in your tablets, you know the significant impact it can have on drug stability and efficacy. Moisture-induced degradation can lead to product recalls, decreased shelf life, and potentially harm the end-users of your products. That is why it is important to find a solution that can address this problem.
At Colorcon, we understand the importance of moisture management in pharmaceuticals. Opadry amb II coating offers a high performance moisture barrier that can protect the integrity of moisture sensitive compounds beyond primary packaging and reduce the risk of moisture-induced degradation to improve the overall stability profile of your drug products.
Our team of experts can work with you to develop a customized solution that fits your specific needs. We provide guidance on the formulation and design of your dosage form, helping you select the right excipients, coatings and packaging to reduce the impact of moisture on your products. So why wait? Contact Colorcon today to learn more about how we can help you solve your moisture management challenges and bring cost-effective drug products to market.
