Ratios of ABR threshold values after 0.05 mL intratympanic injections of
copolymer systems to those before injections in guinea pigs over 28 days
in vivo. The average threshold values of ABR were
35–50 dB before the injections. Injection of 0.1 mL saline was the
control. Symbols: dotted bars, synthesized PLGA-PEG-PLGA; striped bars,
commercial PLGA-PEG-PLGA; open bars, saline (control). D0, D7, D14, D21, and D28
indicate ABR data on 7 days, 14 days, 21 days, and 28 days after the injection, respectively.
8kHz, 16kHz, and 32kHz indicate the frequency. Mean ± 95%
confidence interval (n ≥ 4).