Severe tinnitus induced by off-label baclofen.

Area of Science:

• Neuroscience
• Pharmacology

Background:

• Baclofen, a GABA-B receptor agonist, is FDA-approved for spasticity at doses up to 80 mg/day.
• Off-label use of high-dose baclofen (HDB), up to 400 mg/day, is increasing for alcohol use disorders (AUDs).
• The safety and efficacy of HDB for AUDs are not well-established.

Observation:

• Two patients treated with HDB for AUD developed tinnitus.
• The first patient experienced tinnitus at 180 mg/day, which resolved upon dose reduction to 90 mg/day.
• The second patient developed tinnitus at 210 mg/day, resolving after dose reduction to 60 mg/day.

Findings:

• Tinnitus in both cases was likely attributable to baclofen, as assessed by the Naranjo scale.
• The occurrence of tinnitus appeared to be dose-dependent.
• GABA-B receptor involvement in tinnitus etiology and treatment is a known factor.

Implications:

• HDB may induce severe tinnitus, potentially in a dose-dependent manner.
• Individual susceptibility to baclofen-induced tinnitus may be linked to GABA-B genetic polymorphisms.
• Further research is needed to elucidate the precise mechanisms and identify susceptible individuals.