Interfacial Competition on Drug Crystal Surfaces
Lucas Attia, Massachusetts Institute of Technology
Hydrophobic drugs are increasingly important to small molecule drug discovery. It is estimated that 40% of commercialized therapeutic molecules and 90% of drug candidates in the pharmaceutical development pipeline are hydrophobic. Yet, most hydrophobic drug candidates fail in clinical trials, usually due to their poor oral bioavailability. Enabling the oral bioavailability of hydrophobic drugs relies on cleverly processing drug with inactive ingredients (excipients), particularly polymers and surfactants. Understanding the molecular interactions between drug crystals and excipients during processing has been a bottleneck in developing new formulations that enable oral bioavailability. Here, we use all-atom molecular dynamics (MD) simulations on an HPC system to reveal the interfacial competition between polymers and surfactants on the surface of a model hydrophobic drug crystal. We develop a novel workflow for simulating mixtures of excipients on a crystal surface. We use this workflow to report the first characterization of the change in interfacial structure on a drug crystal surface as a function of composition in realistic excipient mixtures. Simulation results are related to an experimental crystallization system and help explain composition-dependent crystallinity. Our novel workflow can be applied to study candidate drug formulations or generalized to characterize other surface interactions on any molecular crystal.
Abstract Author(s): Lucas Attia, Dien Nguyen, Devashish Gokhale, Talia Zheng, Patrick S. Doyle