Solid dispersions of glimepiride, belonging to the sulfonylurea group of antidiabetic drugs, and poly(ester amide) hyperbranched polymers of different chemical compositions were prepared in order to improve glimepiride's poor water solubility. X-ray powder diffraction results show that glimepiride is innoncrystalline form, indicating that drug molecules are molecularly dispersed within the amorphous hyperbranched polymers. Nuclear magnetic resonance spectroscopy and Fourier transform-infrared spectroscopy results reveal the complex formation between the glimepiride drug and the particular hyperbranched polymer, which was confirmed also by quantum chemical calculations. The complex is stabilized by a hydrogen-bond interaction betweenthe NH group of the sulfonylurea segment of glimepiride and the carbonyls of the amide and ester bonds of the hyperbranched polymers. The slightly acidic proton of the NH group of the sulfonylurea segment of glimepiride is also involved in an interaction with the tertiary amino functional groups of the hyperbranched polymer. As a consequence, the loading capacity is higher for the hyperbranched polymer with the tertiary amino groups. Owing to a complex formation between glimepiride and a particular hyperbranched polymer, glimepiride's water solubility and its dissolution rateare considerably improved relative to the pure glimepiride drug.
COBISS.SI-ID: 4713498
Due to their highly branched structure and the large number of functional groups hyperbranched polymers possess unique properties that make them interesting for uses in a wide variety of applications. Some of the most widely investigated hyperbranched polymers are the polyesters based on 2,2-bis(methylol)propionic acid. In this paper we present the results of characterization studies of hyperbranched polyesters based on 2,2-bis(methylol)propionic acid which show that they are very complex products with a multidimensional distribution of various properties. The influence of the synthesis conditions on the structure and molar-mass characteristics of hyperbranched polyesters as well as the findings that allow a thorough understanding of the structure-property relationships are reviewed in detail.
COBISS.SI-ID: 4487194
The feasibility of incorporating a solid dispersion containing poorly soluble antidiabetic drug glimepiride and poly(ester amide) hyperbranched polymer into a tablet using a direct-compression tabletting technique was investigated. Tablet cores were additionally coated with hydroxypropyl methylcellulose phthalate in order to protect the extremely hygroscopic solid dispersion from atmospheric moisture. Preliminary stability studies show that glimepiride, which is in amorphous form within solid dispersion, is chemically stable, even if tablets are exposed to elevated temperature and/or moisture. In-vitro dissolution studies show some impact of storage conditions on the tablet cores disintegration time and, consequently, drug release rate. Glimepiride solubility also deteriorates somewhat, most probably due to its partial recrystallization. Storage conditions much less affect the physical stability of coated tablets, which was ascribed to reduced tablet hygroscopicity due to the presence of protecting coating. The hyperbranched polymers are rather new and complex macromolecules. Therefore, we addressed also the biocompatibility of hyperbranched polymer, i.e., its impact on haemolysis of the red blood cells. The concentration required for the haemolytic effect on the red blood cells is around 100-times higher than its expected gastrointestinal luminal concentration, which makes the occurrence of hyperbranched polymer mediated cytotoxicity very unlikely.
COBISS.SI-ID: 3075697