75% ASD Loading Shrinks Tablets: AAPS PharmSci 360 2026

Turning a poorly soluble API into an amorphous solid dispersion (ASD) is often necessary for oral bioavailability. The manufacturing route a developer picks, however, affects everything from processing time to final tablet size. PharmTech sat down with Bill Williams, professor and chair at The University of Texas at Austin College of Pharmacy and editor-in-chief of AAPS PharmSciTech, to discuss comparisons between KinetiSol processing with spray drying, drawing on his group's poster at AAPS PharmSci 360.

Williams says the right choice at commercial scale depends on what the API requires. KinetiSol forms ASDs in roughly 10 to 20 seconds. Spray drying takes longer and requires organic solvent, but remains a well-established tool for solubility enhancement.

Drug loading is a key differentiator. Williams notes that a 75% loading, compared with 60% or lower, fits more drug into a smaller tablet. “The higher drug loading you can get, then the less pill burden you have for the dosage form, like a tablet that gets administered to patients,” he says. He cites studies linking smaller pills to better patient compliance.

For weakly basic drugs, release behavior matters as much as loading. Drug that dissolves in the stomach can precipitate once it reaches the higher pH of the upper small intestine. “As a formulator, we’re looking for ASDs that don’t release drug in the acid phase, but then release drug above supersaturation levels and maintain it,” Williams explains.

No process is universal, he adds. Drugs with very high melting points need to be evaluated case by case before KinetiSol is chosen. “What I’ve found over the years is each process has their limitations, and KinetiSol for high melting point drugs, that could be a limitation and just needs to be studied,” Williams says.