Tocainide and tinnitus. Clinical effect and site of action

Tocainide, an amine analogue of lidocaine, which can be taken orally, was tested on 9 patients with severe tinnitus. 6 patients responded to the drug. In 4 patients the effect ceased after about 2 weeks despite continuous medication. 2 patients are still on this medication after more than 2 years. The binding of tocainide to melanin was analysed in vitro and in vivo in rats. It was concluded that the effect of tocainide on tinnitus is mediated by a peripheral mechanism possibly related to the accumulation on inner ear melanin.