Formulation of salicylate-based poly(anhydride-ester) microspheres for short- and long-term salicylic acid delivery

Abstract

The formulation of salicylate-based poly(anhydride-ester) (PAE) microspheres was optimized by altering polymer concentration and homogenization speed to improve the overall morphology. The microspheres were prepared using three salicylate-based PAEs with different chemical compositions comprised of either a heteroatomic, linear aliphatic, or branched aliphatic moiety. These PAEs broadened the range of complete salicylic acid release to now include days, weeks and months. The molecular weight (Mw), polydispersity index (PDI) and glass transition temperature (Tg) of the formulated polymers were compared to the unformulated polymers. In general, the Mw and PDI exhibited decreased and increased values, respectively, after formulation, whereas the Tg changes did not follow a specific trend. Microsphere size and morphology were determined using scanning electron microscopy. These microspheres exhibited smooth surfaces, no aggregation, and size distributions ranging from 2-34 m in diameter. In vitro release studies of the chemically incorporated salicylic acid displayed widely tunable release profiles.

Pharmaceutical suspension containing both immediate/sustained-release amoxicillin-loaded gelatin nanoparticles: preparation and in vitro characterization

“…16,32,33 The release mechanism was calculated from the slope of the appropriate plots and the regression coefficient ( R 2 ) was determined by Sigma Plot software (v 9.01; Systat Software, Inc, San Jose, CA, USA). It was found that the in vitro drug release of GLAN formulations was best explained by two models (Figure 4).…”

Pinosylvin‐Based Polymers: Biodegradable Poly(Anhydride‐Esters) for Extended Release of Antibacterial Pinosylvin

“…PAEs are predominantly surface‐eroding polymers with minimal burst release, allowing for controlled and sustained release of bioactives in a near‐zero order manner . Additionally, PAEs can be prepared to achieve higher bioactive loadings (50%–100%), and formulated into different geometries, hence offering the potential to satisfy diverse applications …”

Tuning salicylate‐based polymers to overcome lag time and extend release via copolymers and polymer blends

“…These polymers undergo hydrolytic degradation and release SA in a controlled fashion, exhibiting near zero‐order kinetics . The physicochemical properties and drug release profiles of the salicylate‐based PAEs can be altered by varying the hydrophobicity of the “linker” molecule . Previous work has shown that increases in the hydrophobicity of the “linker” results in slower drug release and increased lag time (initial degradation period containing little to no drug release) .…”

“…Extended release of SA may be beneficial for the treatment of chronic inflammatory diseases that cause pain; for example, rheumatoid arthritis and osteoarthritis . However, the presence of a significant lag time is unfavorable for sustained and long‐term drug release, as it is the case for salicylate‐based PAEs with branched aliphatic linkers, which manifest a 10‐day lag period . To modify the physicochemical properties and drug release profiles of the salicylate‐based PAEs beyond variation of the “linker” molecule, we explored the use of copolymers and polymer blends.…”