title: Amino acids as co-amorphous excipients for tackling the poor aqueous solubility of valsartan.
abstract: Co-amorphization has recently been shown to be a promising approach for stabilizing amorphous drugs and improving the dissolution rate of poorly water-soluble drugs. In this study, three basic amino acids were chosen as small molecular weight excipients to interact with the drug to form co-amorphous combinations. The co-amorphous combinations of valsartan (VAL) with l-histidine, l-arginine, and l-lysine were prepared by vibrational ball milling. Solid-state characterization with X-ray powder diffraction and differential scanning calorimetry (DSC) revealed that all of the co-amorphous mixtures were homogeneous. The molecular interactions of the co-amorphous mixtures were investigated through the glass transition temperature (Tg) in the DSC measurements and Fourier transform infrared spectroscopy. The drug remained chemically stable during the milling process, and the co-amorphous formulations were generally physically stable over at least 3 months at 40 °C under dry conditions. The dissolution rate of all of the co-amorphous mixtures was significantly increased over that of the amorphous VAL alone. The results of this study demonstrated the potential of amino acids as small molecular weight excipients in co-amorphous formulations to improve the drug solubility and dissolution rate.
authors.affiliation: a Pharmaceutical Analytical & Solid-State Chemistry Research Center, Shanghai Institute of Materia Medica, Chinese Academy of Sciences , Shanghai , China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Huang
authors.affiliation: a Pharmaceutical Analytical & Solid-State Chemistry Research Center, Shanghai Institute of Materia Medica, Chinese Academy of Sciences , Shanghai , China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: a Pharmaceutical Analytical & Solid-State Chemistry Research Center, Shanghai Institute of Materia Medica, Chinese Academy of Sciences , Shanghai , China.
authors.forename: Jian-Rong
authors.initials: JR
authors.lastname: Wang
authors.affiliation: a Pharmaceutical Analytical & Solid-State Chemistry Research Center, Shanghai Institute of Materia Medica, Chinese Academy of Sciences , Shanghai , China.
authors.forename: Kai-Lei
authors.initials: KL
authors.lastname: Lin
authors.affiliation: a Pharmaceutical Analytical & Solid-State Chemistry Research Center, Shanghai Institute of Materia Medica, Chinese Academy of Sciences , Shanghai , China.
authors.forename: Xuefeng
authors.initials: X
authors.lastname: Mei
mesh_terms: D000596:Amino Acids / Q000737:chemistry*; D000959:Antihypertensive Agents / Q000737:chemistry*; D001120:Arginine / Q000737:chemistry; D002152:Calorimetry, Differential Scanning; D004355:Drug Stability; D005079:Excipients / Q000737:chemistry*; D006639:Histidine / Q000737:chemistry; D008239:Lysine / Q000737:chemistry; D033362:Powder Diffraction; D012995:Solubility; D017550:Spectroscopy, Fourier Transform Infrared; D044366:Transition Temperature; D000068756:Valsartan / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D000596:Amino Acids; D000959:Antihypertensive Agents; D005079:Excipients; D006639:Histidine; D000068756:Valsartan; D001120:Arginine; D008239:Lysine
keywords: Amino acid; co-amorphous; intrinsic dissolution rate; small molecular excipients; solubility; valsartan