title: Acid-base interactions in amorphous solid dispersions of lumefantrine prepared by spray-drying and hot-melt extrusion using X-ray photoelectron spectroscopy.
abstract: This study investigates drug-excipient interactions in amorphous solid dispersions (ASDs) of the model basic compound lumefantrine (LMN), with five acidic polymers. X-ray photoelectron spectroscopy (XPS) was used to measure the extent of the protonation of the tertiary amine in LMN by the five acidic polymers. The extent/efficiency of protonation of the ASDs was assessed a function of polymer type, manufacturing process (hot-melt extrusion vs. spray drying), and drug loading (DL). The most strongly acidic polymer, polystyrene sulfonic acid (PSSA) was found to be the most efficient polymer in protonating LMN, independently of manufacturing method and DL. The rank order for the protonation extent of LMN by each polymer is roughtly the same for both manufacturing processes. However, protonation efficiency of polymers of similar acidic strength ranged from ∼0% to 75% (HPMCAS and Eudragit L100-55, respectively), suggesting an important role of molecular/mixing effects. For some polymers, including Eudragit L100 55 and HPMCP, spray-drying resulted in higher protonation efficiency compared to hot-melt extrusion. This result is attributable to a more favorable encounter between acid and base groups, when exposed to each other in solution phase. Increasing DL led to decreased protonation efficiency in most cases, particularly for polyacrylic acid, despite having the highest content of acidic groups per unit mass. These results indicate that the combined effects of acid strength and mixing phenomena regulate the efficiency of acid-base interactions in the ASDs.
authors.affiliation: Department of Industrial and Physical Pharmacy, Purdue University, West Lafayette, IN 47907, United States.
authors.forename: Yang
authors.initials: Y
authors.lastname: Song
authors.affiliation: Birck Nanotechnology Center, Purdue University, West Lafayette, IN 47907, United States.
authors.forename: Dmitry
authors.initials: D
authors.lastname: Zemlyanov
authors.affiliation: GlaxoSmithKline, Collegeville, PA 19426, United States.
authors.forename: Xin
authors.initials: X
authors.lastname: Chen
authors.affiliation: U.S. Food and Drug Administration, Silver Spring, MD 20993, United States.
authors.forename: Ziyang
authors.initials: Z
authors.lastname: Su
authors.affiliation: Department of Industrial and Physical Pharmacy, Purdue University, West Lafayette, IN 47907, United States.
authors.forename: Haichen
authors.initials: H
authors.lastname: Nie
authors.affiliation: Small Molecule Pharmaceutical Sciences, Genentech, Inc., South San Francisco, CA 94080, United States.
authors.forename: Joseph W
authors.initials: JW
authors.lastname: Lubach
authors.affiliation: Department of Industrial and Physical Pharmacy, Purdue University, West Lafayette, IN 47907, United States.
authors.forename: Daniel
authors.initials: D
authors.lastname: Smith
authors.affiliation: Department of Industrial and Physical Pharmacy, Purdue University, West Lafayette, IN 47907, United States.
authors.forename: Stephen
authors.initials: S
authors.lastname: Byrn
authors.affiliation: Department of Industrial and Physical Pharmacy, Purdue University, West Lafayette, IN 47907, United States. Electronic address: rpinal@purdue.edu.
authors.forename: Rodolfo
authors.initials: R
authors.lastname: Pinal
mesh_terms: D000143:Acids / Q000737:chemistry*; D004339:Drug Compounding / Q000379:methods*; D004355:Drug Stability; D004983:Ethanolamines / Q000737:chemistry*; D005449:Fluorenes / Q000737:chemistry*; D000078102:Lumefantrine; D056951:Photoelectron Spectroscopy; D011108:Polymers / Q000737:chemistry*; D011208:Powders / Q000737:chemistry
chemical_list: D000143:Acids; D004983:Ethanolamines; D005449:Fluorenes; D011108:Polymers; D011208:Powders; D000078102:Lumefantrine
keywords: Acid-base; Amorphous; Hot-melt extrusion; Ionic interaction; Lumefantrine; Salt; Solid dispersion; Spray-drying; XPS