Beyond the Drying Curve: Aldo Vidinha on Tackling Overdried Granules in Modern Pharma Manufacturing

Precision in drying defines the strength of every tablet

In pharmaceutical manufacturing, success often depends on mastering small details. Few steps show this balance better than the drying stage of granulation. For many production teams, it seems like a routine operation. But according to Aldo Vidinha, Senior Technical Operations Freelance Consultant, it is one of the most misunderstood and underestimated parts of the process.

“Drying is not only about removing moisture,” Vidinha explains. “It is about managing it carefully. If you take it too far, you can damage the product before it even reaches the press.”

The Moisture Paradox

In wet granulation, powder particles are blended with a binder solution to create a cohesive mass. Drying then removes excess water, but a small amount of residual moisture—typically between 1% and 3%—is essential for proper compression and tablet strength. When drying time or temperature goes beyond validated parameters, granules become brittle. The result is a range of mechanical problems such as tablet capping, lamination, and poor compressibility.

“Production efficiency often pushes teams to shorten cycles or raise temperatures,” Vidinha says. “But every extra minute or degree beyond what is validated can harm product quality.”

The Science of Control

Vidinha describes overdrying as both a technical and operational challenge. Technically, it occurs when critical variables such as temperature, airflow, or drying time are not properly controlled. Operationally, it often stems from a production mindset that prioritizes speed over stability.

“We used to focus on throughput,” Vidinha says. “Now, as formulations become more complex, drying needs to be treated as a living process that responds to the material, not just a timer on a machine.”

Modern production facilities are starting to adopt real-time moisture sensors, near-infrared spectroscopy (NIR), and predictive process models. These tools allow operators to monitor drying in real time and stop the process when the material reaches its optimal moisture level. Vidinha refers to this approach as “adaptive control,” where decisions are made based on data, not assumptions.

Recovering from Overdrying

When overdrying does occur, it can sometimes be corrected. The white paper outlines a controlled re-moistening method, where the same solvent used in granulation is applied in a measured quantity, followed by mixing and sieving.

“Reintroducing moisture can help, but it has to be done precisely,” Vidinha cautions. “Too little and the granules remain brittle. Too much and they start sticking during compression.”

He adds that recovery should be a last resort. Prevention, supported by proper training and process validation, is a far more reliable strategy.

From Process to Philosophy

For Vidinha, overdrying highlights a larger issue in the pharmaceutical industry: the gap between process control and material science. His work at Consultant focuses on helping manufacturers understand that gap and design smarter, more consistent systems.

“Machines perform the work, but humans must understand the materials,” he says. “When you know how your materials behave, you can design processes that respect those limits.”

This philosophy underpins StepScience’s approach to pharmaceutical engineering, which combines technical precision with a deep understanding of how real-world production environments operate.

The Future of Drying

As continuous manufacturing and digital twins become more common, the drying stage is evolving rapidly. Closed-loop feedback systems and automated moisture monitoring are helping to eliminate human error and reduce energy waste. Vidinha believes that with the right approach, overdrying can become a problem of the past.

“When we start managing moisture as a critical parameter of performance, not just something to remove, we will reach a new level of consistency in manufacturing,” he says.

For an industry defined by precision, Vidinha’s message is clear: control the details, respect the materials, and quality will follow.