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VMAT 2 inhibitors such as valbenazine and deutetrabenazine have been approved for treatment of TD by the FDA6, 8 and is the first line drug to treat TD. However, it is not available in our setting. Therefore, an alternate treatment, clonazepam was considered which has some evidence in the treatment of TD. The American Academy of Neurology grades clonazepam as grade B level of evidence which means it is probably effective in the treatment of TD.6, 7, 13

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Although cessation of chlorpromazine and risperidone could have contributed to the remission of his TD symptoms, we believe that the fact clonazepam did actually facilitate the recovery. This is because his TD symptoms were deteriorating when he was being observed before clonazepam was started. His TD symptoms started to diminish after he was put on clonazepam and as the dose was gradually increased the response was even better.

The use of Clonazepam in the treatment of TD was studied from the 1970s–1980s and since then several case reports have reported its success.15, 16 Clonazepam is a long-acting benzodiazepine. Benzodiazepines bind to GABA type A receptors allosterically and increase the frequency of chloride channel opening thereby hyperpolarizing the neurons.7, 10 The GABAergic system has been involved in the pathophysiology of TD and reduction of GABA levels in the basal ganglia have been found in association with TD.7, 10 Additionally, Chih Chun et al. described that a significant number of patients did not exhibit improvement in their symptoms with VMAT2 inhibitors, and that dopamine blockage may not be the only reason in genesis of TD.10

Furthermore, in a 12 week, double-blind, randomized, placebo crossover trial of 19 chronically ill patients with TD taking the FGAs, clonazepam treatment reduced dyskinesia scores by 37% compared with placebo.6 Doses up to 4.5 mg/day of clonazepam have been used and reported in some studies.5, 10 However, it has also been reported that benzodiazepines do induce TD5 and reappearance of TD symptoms have been reported with cessation of benzodiazepine treatment.15



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