Understanding Of Amorphous Solid Dispersions & Their Downstream Development

By Jim Huang, PhD, Founder & CEO, Ascendia Pharmaceuticals

Amorphous solid dispersion (ASDs), in which drug is amorphously dispersed within polymer(s), would significantly increase drug dissolution rate by a simultaneous increase in local aqueous solubility as a result of amorphous formation and excipient solubilization effects, and in dissolution surface area by a reduction in particle size to the minimum level. Amorphous solid dispersions have experienced an exponential growth since the late 1990s. This phenomenon is partially attributed to the current need to address the high percentage of poorly water-soluble compounds in drug pipelines and the availability of new large-scale manufacturing technologies, eg, spray dried, liquid (melt)-filled capsules and hot-melt extrusion. A few new ASD products manufactured by various technologies have gained marketing approval since 2000. However, due to the lack of full understanding of solid dispersion properties and reliable prediction of product scale up, stability, and in-vivo performance, ASDs are still not fully utilized in drug delivery of drug candidates in clinical and commercial stages.