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Vitamin B6 for tardive dyskinesia?

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Although antipsychotics have revolutionized the treatment of severe mental illnesses, adverse effects often present a substantial obstacle to adherence. One of the most tenacious and difficult-to-treat adverse effects is tardive dyskinesia (TD), a neuromotor syndrome with characteristic involuntary repetitive movements, typically of the muscles of the jaw, lips, and tongue. In addition to spasms and grimacing, patients can have choreoathetoid movements of the neck. In more extreme presentations, some patients can have difficulty breathing. TD is a largely irreversible condition. It is often a disfiguring lifelong disability that can further stigmatize patients who already suffer scorn and derision. TD usually has a delayed onset after a patient is started on an antipsychotic.1 The syndrome is more commonly associated with first-generation antipsychotics, but affects up to 20% of patients who are treated with second-generation antipsychotics.1 In the United States, TD affects as many as 500,000 patients.1

There are several palliative interventions for TD, but the evidence for a consistently reliable treatment is weak. Branched-chain amino acids, ginkgo biloba, melatonin, and vitamin E have been investigated as interventions. Other approaches include switching to an alternate antipsychotic such as clozapine, adjusting the antipsychotic dose, using anticholinergic medications, adjunctive amantadine, gamma aminobutyric acid agonists, or adding tetrabenazine.

The FDA recently approved two vesicular monoamine transporter 2 (VMAT2) inhibitors, deutetrabenazine and valbenazine, for addressing symptoms of TD. However, these medications can cost tens of thousands of dollars per year, and also carry the risk of adverse effects such as sedation, akathisia, urinary retention, constipation, and muscle pain.2 When treating a patient who develops TD, one might consider other potentially effective therapies with low adverse effect profiles that may be more cost-effective than existing treatments. The bioactive form of vitamin B6 (pyridoxine), pyridoxal-5-phosphate, has been used to treat various antipsychotic-induced movement disorders. Preliminary evidence suggests that vitamin B6 may help reduce the symptoms of TD.

A recent Cochrane Database Review (2015)3 of pyridoxal-5-phosphate treatment for TD found a significant improvement in symptoms compared with placebo. Although the studies included in this review were limited by modest sample sizes and short follow-up periods, 2 of the investigations revealed improvements of >40% in extrapyramidal symptoms with vitamin B6 compared with placebo. Lerner et al (2001)4 conducted a randomized, double-blind, placebo-controlled crossover trial in which 15 inpatients with schizophrenia who met the criteria for TD were assigned to vitamin B6, 400 mg/d, or placebo for 4 weeks. After a 2-week washout period, the placebo group was given vitamin B6 and vice versa. Compared with placebo, mean scores on the parkinsonism and dyskinetic movement subscales of the Extrapyramidal Symptom Rating Scale were significantly better in the third week of treatment with vitamin B6.

Lerner et al (2007)5 later conducted a separate crossover study using the same design with a washout period. This trial included a larger sample size (50 inpatients with DSM-IV diagnoses of schizophrenia or schizoaffective disorder and TD) and the dosage of vitamin B6 was increased to 1,200 mg/d over 26 weeks. Patients who received vitamin B6 experienced a significantly greater decrease in Extrapyramidal Symptom Rating Scale scores compared with those in the placebo group.

Continued to: A 29-year-old woman with treatment-resistant schizophrenia...

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