The chronic use and high dosing of typical
neuroleptics or centrally acting
dopamine receptor blocking
antiemetics predispose patients to the onset of tardive syndromes. One particular subtype,
tardive dyskinesia, is characterized by rapid, repetitive, stereotypic,
involuntary movements of the face, limbs or trunk. The inhibition of the
vesicular monoamine transporter system, using
tetrabenazine therapy, improves the severity of
tardive dyskinesia. But there are also drawbacks to
tetrabenazine treatment, such as a fluctuating response and the need for frequent intake due to its rapid metabolism. Clinical research on the potentially more efficacious and easier to use
tetrabenazine analogs is already under way. One of them is
valbenazine, the purified parent
drug of the (+)-α-isomer of
tetrabenazine. The FDA lowered approval hurdles for
valbenazine due to a successful Phase II trial, which showed a distinctive improvement in
tardive dyskinesia symptoms during
valbenazine administration. This resurgence in the clinical research of tardive syndrome
therapy is most welcome. This author notes that the putative long-term side effects of
valbenazine should carefully be investigated in the future via naturalistic observational trials. Furthermore,
valbenazine may also support the onset of symptoms, such as
Parkinsonism and depression, with chronic administration, as it, to a certain extent, shares the mode of action of
tetrabenazine.