To analyze polyesteramide (PEA) microparticles (“MPs”) interaction with reagents used in histological analysis and their compatibility with the steps required for ocular injection.Methods
Unloaded- and dye-loaded (Chromoionophore II) PEA III MPs suspended in PBS/mannitol were: i) analyzed under light and fluorescence optic microscopy; ii) exposed to reagents, solutions and processes required to perform histological procedures; iii) released through different needle gauges and quantified in a Neubauer chamber. Rat eyes were divided into two groups: intravitreal injection (n= 20) and subtenon/subconjuntival injection (n=24). After sacrifice, tissues were processed as retinal whole-mount and cryosections.Results
i) PEA III MPs were stable when contacted with distilled water, PBS, 4% PF and 2% glutaraldehyde; ii) PEA III MPs lost shape or dissolved when in contact with Xylene, EtOH or acetone; iii) freezing at -20°C and heating at 60°C does not impact particles re-dispersion, shape and polydispersity; iv) no significant differences in MPs number released through different needle gauges (25G, 27G, 30G, 32G) were found; v) in unstained tissues, MPs preserved their morphological characteristics and coalesced into depots.Conclusion
MPs: i) are compatible with some of the steps required for routine histological processing. ii) can be released through needle gauges used in human clinical setting; iii) the injection should be done during the 30 minutes following suspension preparation.