Adenosine amine congener as a cochlear rescue agent.

UNLABELLED: We have previously shown that adenosine amine congener (ADAC), a selective A1 adenosine receptor agonist, can ameliorate noise- and cisplatin-induced cochlear injury. Here we demonstrate the dose-dependent rescue effects of ADAC on noise-induced cochlear injury in a rat model and establish the time window for treatment.

METHODS: ADAC (25-300 μg/kg) was administered intraperitoneally to Wistar rats (8-10 weeks old) at intervals (6-72 hours) after exposure to traumatic noise (8-16 kHz, 110 dB sound pressure level, 2 hours). Hearing sensitivity was assessed using auditory brainstem responses (ABR) before and 12 days after noise exposure. Pharmacokinetic studies investigated ADAC concentrations in plasma after systemic (intravenous) administration.

RESULTS: ADAC was most effective in the first 24 hours after noise exposure at doses >50 μg/kg, providing up to 21 dB protection (averaged across 8-28 kHz). Pharmacokinetic studies demonstrated a short (5 min) half-life of ADAC in plasma after intravenous administration without detection of degradation products.

CONCLUSION: Our data show that ADAC mitigates noise-induced hearing loss in a dose- and time-dependent manner, but further studies are required to establish its translation as a clinical otological treatment.