The Benefits of Using Dynamic Vapor Sorption (DVS) in Pharmaceutical Production Development
Dynamic Vapor Sorption (DVS) is a powerful analytical technique widely used in the pharmaceutical industry to measure the amount of vapor absorbed or desorbed by a sample under controlled conditions of temperature and humidity. This technique provides critical insights into the behavior of pharmaceutical materials, impacting various properties from stability and shelf life to formulation and manufacturing processes. Here, we explore the numerous benefits of DVS in the pharmaceutical industry.
Amorphous Content Determination
One significant benefit of DVS is its ability to detect low levels of amorphous content in pharmaceutical powders. Amorphous content in pharmaceutical materials can lead to instability and reduced efficacy due to their tendency to absorb more moisture, causing phase transitions and product degradation. The DVS is an effective method to quantify amorphous content by analyzing moisture sorption isotherms. It allows scientists to calibrate known amorphous contents or identify vapors that induce crystallization, thereby understanding the extent of amorphous phases.
For example, data shows where the crystallization of a pharmaceutical ingredient was induced using ethanol as a solvent. After establishing a baseline, the system was adjusted to a low partial pressure environment before initiating crystallization at 30% p/p0. To induce a phase change, ethanol concentration was then increased to 85% p/p0, resulting in the formation of a crystalline material. Due to the formation of a structured crystalline lattice, there was a reduced uptake of ethanol when the system returned to 30% p/p0 in the third stage of the experiment. The amorphous content was calculated based on the difference in ethanol uptake between the first and third steps of the experiment. Such studies enhance pharmaceutical stability and shelf life by identifying and controlling unstable amorphous regions.
Analysis of Drug-Excipient Moisture Interactions
Moisture sorption isotherms, which describe the equilibrium moisture content of a material at different relative humidity levels, are essential for understanding and predicting the behavior of pharmaceuticals under various environmental conditions. DVS allows for precise measurement of these isotherms, providing detailed insights into the hygroscopicity of both active pharmaceutical ingredients (APIs) and excipients. This information is crucial for designing stable and effective formulations.
For example, by analyzing the moisture sorption properties of hydrophobic pharmaceutical substances, such as Lovastatin, we can see how it interacts with moisture in contrast to hydrophilic substances like hydroxypropyl cellulose (HPC) and microcrystalline cellulose (MCC). The DVS reveals how these materials interact with moisture, helping in selecting suitable excipients and optimizing formulations to enhance drug performance and shelf life.
Determination of Glass Transition RH
The DVS can determine the critical relative humidity (RH) at which a glass transition occurs. This is important because the glass transition can lead to significant changes in a material’s physical properties.
Figure 3 shows a DVS ramping experiment coupled with a camera to analyze spray-dried lactose. The experiment starts with a stable baseline and then increases the relative humidity by 10% per hour up to 90%. Initially, moisture adsorbs on the surface. As RH increases, lactose undergoes a glass transition, where moisture penetrates the bulk, increasing molecular mobility and facilitating recrystallization above 80% RH. This absorbed moisture acts as a plasticizer, promoting the rearrangement of lactose molecules into a stable crystalline form. Further increases in RH lead to material decomposition. In identifying the glass transition RH, manufacturers can better understand and control the storage and processing conditions of amorphous pharmaceuticals.
Packaging Materials
Packaging materials play a crucial role in protecting pharmaceutical products from environmental factors, and their ability to interact with moisture can significantly impact the shelf life and quality of the packaged goods. The DVS can be used to understand how packaging materials absorb and desorb moisture under varying humidity conditions, providing insights into their water-vapor transmission rates and barrier properties.
By exposing packaging samples to controlled humidity levels and continuously measuring the weight changes, the DVS can determine moisture diffusion coefficients. This information is important for selecting appropriate packaging materials that maintain product stability and prevent issues such as spoilage, caking, or loss of flavor and aroma. Moreover, DVS can identify critical humidity thresholds that might induce phase transitions or degradation in packaging materials, allowing manufacturers to design more effective packaging solutions that ensure longer shelf life and better preservation of pharmaceutical products.
Improvement in Quality Control and Assurance
DVS serves as a powerful tool for quality control in pharmaceutical manufacturing. It ensures that materials meet the required specifications for moisture content, which is crucial for maintaining product quality and compliance with regulatory standards. Regular use of DVS in quality assurance processes ensures that each batch of the product is consistent with the intended specifications.
Dynamic Vapor Sorption (DVS) is an indispensable tool in the pharmaceutical industry, offering enhanced sensitivity, detailed moisture sorption analysis, and valuable insights into drug-excipient interactions. Its ability to detect low levels of amorphous content, study complex formulations, and ensure product stability and quality makes it a crucial technique for pharmaceutical research, development, and manufacturing. In the research and development phase, the DVS accelerates the formulation process by providing quick and accurate data on the moisture-related properties of new compounds and formulations. This enables researchers to make informed decisions early in the development process, reducing the time and cost associated with bringing new drugs to market. As the industry continues to evolve, the role of DVS in ensuring the efficacy and safety of pharmaceutical products will only become more prominent, driving innovation and improving patient outcomes.