Alprazolam (Xanax) 250mg tablets.
Some patients experienced relief of their tinnitus while on alprazolam. This led to a controlled study by Johnson et al (1993). Of the 17 patients who completed the trial, 13 had a reduction of their tinnitus (76%). The authors also explained the action through its GABAergic effect. Although this result sounds promising, alprazolam is known to lead to dependence/addiction, therefore, as with diazepam, utmost care is needed in the consideration of the use of this drug.
Other antiepileptic drugs suggested for tinnitus treatment:
Vigabatrin (Sabril) 500mg tablets.

This drug is a GABA agonist. A trial by Perucca et al (1991) suggested benefit but Coles failed to replicate this (personal communication).

Lamotrigine (Lamictal) 25mg tablets.
This candidate, like vigabatrin, is under research.

Research studies show that benzodiazepines work through their effect on gamma aminobituric acid A (GABA A) receptors. GABA A has an inhibitory effect on ascending auditory pathways as well as at cochlea level. It has been shown that benzodiazepines enhance the GABA A effect and through this the effects are
(i) sedative (ii) anxiolytic (iii) anticonvulsant (iv) attenuation of autonomic and endocrine responses. Hence in theory one expects benefit not only directly on tinnitus but also on emotional and autonomic consequences. However in the use of benzodiazepines there are problems of dependency/addiction, tolerance and rebound.
Earlier amitriptyline and trimipramine were thought to have a direct effect on tinnitus along with the antidepressant effect. However the direct effect is doubtful. Later another drug in this group (nortriptyline) was suggested to have tinnitolytic effect.

Nortriptyline (Allegron, Motipress, Motival) 25mg tablets.

Of studies comparing tinnitus patients and tinnitus patients with depressive disorder, (Dobie et al. 1993) this drug was found to have beneficial effect upon depression but no significant effect upon tinnitus.

Cinnarizine (stugeron) 15mg tablets
Flunarizine (not available in the UK)

These are used in the management of vertigo. They have also some cerebral vasodilator effect. They have been prescribed in the hope that they may help other inner ears related symptoms along with vertigo.

Nictoinic acid (Hexopal; 500mg tablets, Ronicol; 500mg tablets)
Naftidrofuril oxalate (Praxilene) 100mg capsules
Betahistine Hydrocholoride (Serc) 8 and 16mg tablets.
These drugs are used to improve cerebral circulation as vasodilators. Betahistine has been promoted as a specific treatment for Meniere's disease claiming to improve the labyrinthine circulation. In some patients the severity and frequency of vertiginous attacks are reduced, however its effect on tinnitus is not certain
Based on the knowledge that i) extra and intracellular calcium concentration is of critical importance for sound transduction, ii) drug induced tinnitus can be attenuated by providing the subject with an extragenous calcium supplement and iii) L-type calcium channel blockers are effective in alleviating drug induced tinnitus (Jastreboff, 1995) an L-type calcium channel blocker, Nipodipine has been a good candidate for drug trial.
NIMODIPINE (Nimotop) 30mg tablets.
Davies et al. (1994) found in an 8 week trial that 5 of 31 patients reported great improvement, 2 found worsening of tinnitus. Four of those with improvement in their tinnitus continued a further 4 weeks of the drug, minimum masking level measures showed reduction in their tinnitus. Further research is required before conclusions may be drawn concerning these data.