This drug is stupid. It has to be continuously delivered.
"After constant perfusion of gacyclidine for 40-63 h, four out of six patients experienced a temporary relief from their tinnitus. No serious side effects were recorded in any of the cases. Gacyclidine might present a potent drug for the suppression of sensorineural tinnitus in humans and therefore should be considered for future double-blinded, placebo-controlled clinical trials. For lasting effective treatment, controlled intracochlear and long-term delivery of the drug seems to be necessary."
https://www.researchgate.net/public...perfusion_on_tinnitus_in_humans_A_case_series
However, it is interesting that local cochlear delivery of this drug suppresses tinnitus.
Whoops there goes muh tinnitus is in muh brain theory.