Moisture sorption by polymeric excipients commonly used in amorphous solid dispersions and its effect on glass transition temperature: III. Methacrylic acid-methyl methacrylate and related copolymers (Eudragit®)
Moisture sorption by polymeric carriers used in amorphous solid dispersion (ASD) plays a critical role in the physical stability of the dispersed drug as it can increase molecular mobility of drug in ASD by decreasing the glass transition temperatures (Tg) of the drug-polymer system, leading to drug crystallization. The present report describes Part III of a systematic investigation of moisture sorption by different polymers used in ASDs, where the results for four chemically different methacrylic acid-methyl methacrylate and related copolymers, namely, Eudragit® EPO, Eudragit® L100-55, Eudragit® L100, and Eudragit® S100, as the function of relative humidity (RH) are presented.
Effects of moisture sorption on Tg of the polymers were also determined. Among the polymers, Eudragit® EPO is the least hygroscopic, having absorbed, for example, 1.3% w/w moisture at 25 °C/60% RH, while the three other polymers absorbed 4.7–7.5% w/w moisture at the same condition. The moisture sorption was relatively lower at 40 °C than that at 25 °C. The apparent Tg of polymers decreased with the increase in moisture content; however, Tg values remained higher than the usual storage temperature of ASD (25 °C) even at high RH, indicating that the effect of moisture sorption on the physical stability of ASD could be minimal when these polymers are used in ASDs.
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Nirali G. Patel, Sabrina Banella, Abu T.M. Serajuddin, Moisture sorption by polymeric excipients commonly used in amorphous solid dispersions and its effect on glass transition temperature: III. Methacrylic acid-methyl methacrylate and related copolymers (Eudragit®), International Journal of Pharmaceutics, Volume 636, 2023, 122745, ISSN 0378-5173, https://doi.org/10.1016/j.ijpharm.2023.122745.
See also the first two interesting articles in the small series from Abu Serajuddin et al.:
- Part 2: Moisture sorption: Cellulosic Polymers
- Part 1: Moisture sorption: Polyvinylpyrrolidone and related copolymers