Critical properties of lactide-co-glycolide polymers for the use in microparticle preparation by the Aerosol Solvent Extraction System

• Published in: International journal of pharmaceutics 1999-08, Vol.185 (1), p.61-72
• Main Authors: Engwicht, A., Girreser, U., Müller, B.W.
• Format: Article
• Language: English
• Subjects: Aerosols; Biocompatible Materials - chemical synthesis; Biocompatible Materials - chemistry; Biological and medical sciences; Calorimetry, Differential Scanning; Chemistry, Pharmaceutical; General pharmacology; Humans; Lactic Acid - chemical synthesis; Lactic Acid - chemistry; Magnetic Resonance Spectroscopy; Medical sciences; Microparticles; Microscopy, Electron, Scanning; Microspheres; NMR; Particle Size; Pharmaceutical technology. Pharmaceutical industry; Pharmacology. Drug treatments; Polyglycolic Acid - chemical synthesis; Polyglycolic Acid - chemistry; Polylactic Acid-Polyglycolic Acid Copolymer; Polylactide-co-glycolide; Polymers - chemical synthesis; Polymers - chemistry; Powder diffraction; Prostheses and Implants; Solvents; Supercritical fluids; Thermal analysis
• ISSN: 0378-5173; 1873-3476
• DOI: 10.1016/S0378-5173(99)00127-1

The Aerosol Solvent Extraction System (ASES) process uses supercritical carbon dioxide for the production of microparticles. Since the critical temperature for this gas is at 304 K, polymers that are used in this process must fulfil certain requirements in crystallinity, and thermal behavior. This can be achieved by the use of blocked copolymers and thus the presence of semicrystalline microdomains in the polymers. However, changing the sequences of the comonomers dilactide and lactide often leads to polymers of low solubility due to long glycolide blocks. In this study, the critical properties of two blocked co-polymers were investigated, such as the blocked structure itself by 1H-NMR and 13C-NMR, the thermal behavior by differential scanning calorimetry (DSC), and the crystallinity by powder diffraction. The impact of these properties on microparticles formed by those polymers was also object of these studies. Additionally, two different model drugs, albumin and estriolm were embedded to investigate the impact of different polymer properties on drug content and release.