Amino Acids as Co-amorphous Excipients for Simvastatin and Glibenclamide: Physical Properties and Stability

作者：Laitinen Riikka^*; Lobmann Korbinian; Grohganz Holger; Strachan Clare; Rades Thomas

来源：Molecular Pharmaceutics, 2014, 11(7): 2381-2389.

DOI：10.1021/mp500107s

• amorphous
• co-amorphous
• amino acid
• stability
• tautomerism

Co-amorphous drug mixtures with low-molecular-weight excipients have recently been shown to be a promising approach for stabilization of amorphous drugs and thus to be an alternative to the traditional amorphous solid dispersion approach using polymers. However, the previous studies are limited to a few drugs and amino acids. To facilitate the rational selection of amino acids, the practical importance of the amino acid coming from the biological target site of the drug (and associated intermolecular interactions) needs to be established. In the present study, the formation of co-amorphous systems using cryomilling and combinations of two poorly water-soluble drugs (simvastatin and glibenclamide) with the amino acids aspartic acid, lysine, serine, and threonine was investigated. Solid-state characterization with X-ray powder diffraction, differential scanning calorimetry, and Fourier-transform infrared spectroscopy revealed that the 1:1 molar-combinations simvastatin-lysine, glibendamide-serine, and glibendamide threonine and the 1:1:1 molar combination glibenclamide serine threonine formed co-amorphous mixtures. These were homogeneous single-phase blends with weak intermolecular interactions in the mixtures. Interestingly, a favorable effect by the excipients on the tautomerism of amorphous glibenclamide in the co-amorphous blends was seen, as the formation of the thermodynamically less stable imidic acid tautomer of glibenclamide was suppressed compared to that of the pure amorphous drug. Furthermore, the co-amorphous mixtures provided a physical stability advantage over the amorphous drugs alone.

• 出版日期2014-7