ADVANCEMENTS IN CHARACTERIZING THIXOTROPIC PROPERTIES FOR ENHANCED DRUG DELIVERY SYSTEMS: A COMPREHENSIVE REVIEW

Abhijeet Welankiwar*, Shrijit Ghadekar and Pradyumna Keche

ABSTRACT

The way a substance's thickness changes under stress, known as thixotropy, is vital for many drug products like
liquids and creams. It means a substance gets thinner when stirred or shaken, then thickens again when left s till.
This behavior is key to keeping medications stable, ensuring consistent doses, and controlling how quickly the drug
is released into the body, which improves how well the medicine works and how easy it is for patients to use.
Thixotropy is typical in fluids that don't behave like water, where thickness changes with force. The opposite,
where a substance thickens with stress (rheopexy), also matters in some drug formulations. To measure thixotropy,
scientists use both older and newer methods. Older met hods, like hysteresis loops, assess the energy needed for
structural changes, but they have limitations. Newer techniques, such as SAOS and 3ITT, offer more precise
measurements of how the substance breaks down and recovers. SAOS looks at how materials rea ct to small
stresses, while 3ITT examines recovery by applying different stress levels. Incorporating real time monitoring
through PAT has transformed how thixotropy is managed in drug manufacturing. Tools like in line viscometers and
Raman spectroscopy al low for continuous quality checks, ensuring consistent batches and optimized processes.
Regulatory bodies like the USFDA encourage PAT to improve process understanding and maintain high quality.
Real time monitoring of thickness changes and structural reco very has boosted manufacturing efficiency, reduced
errors, and increased product reliability. For example, gels made with methylcellulose show structural recovery,
which is essential for controlled drug release. This underlines the importance of detailed a nalysis for creating
effective drug formulations. Future improvements in thixotropy analysis will likely include combining real time
monitoring with machine learning for better quality control. Combining traditional and modern tools will provide a
deeper u nderstanding of thixotropy in complex drug systems, enhancing stability, manufacturing, and patient
outcomes. This overview examines thixotropy in drug formulations, covering measurement techniques,
applications, and the role of PAT in quality control. By blending classic and innovative monitoring tools, the
pharmaceutical industry can achieve more accurate formulation development, highlighting thixotropy's critical role
in drug design and delivery.

Keywords: Thixotropy, PAT Tools, Newtonian, Non-Newtonian, Viscosity.