Low-dose, long-term caroverine administration attenuates impulse noise-induced hearing loss in the rat.

Physiological and morphological assessments indicated that low-dose and long-term caroverine delivery might be a new approach to protect against impulse noise-induced hearing loss. Although the exact mechanisms by which impulse noise causes hearing loss are still unclear, there is accumulating evidence that increased reactive oxygen species (ROS) production and excessive glutamate released from the inner hair cells lead to hair cell loss and consequently hearing loss. Caroverine is an antagonist of two glutamate receptors, alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and N-methyl-D-aspartate (NMDA) receptors in the inner ear, as well as an antioxidant. In this study, caroverine was delivered subcutaneously using an osmotic pump. This kind of delivery has the advantage, via continuous, long-term and low dose drug administration, of avoiding systemic side effects. It was shown that caroverine could significantly protect the cochlea against impulse noise trauma.