Table 1: Dosage and Administration of VMAT2 Inhibitors.
| Dosage and Administration | Valbenazine [8](Ingrezza) | Tetrabenazine [9] (Xenazine) | Deutetrabenazine [10](Austedo) |
|---|---|---|---|
| Strengths and Dosage Form | 40 mg capsules | 12.5 mg and 25 mg tablets | 6 mg, 9 mg, and 12 mg tablets |
| Recommended Starting Dose | 40 mg daily with or without food | 12.5 mg daily for the first week, then 12.5 mg twice daily | 6 mg daily with food |
| Dose Adjustments |
• Dose can be increased to 80 mg daily • Patients with moderate-severe hepatic impairment: Do not exceed 40 mg/day • Poor metabolizers (PM) of CYP2D6 may need dose reductions |
• Dose can be titrated by 12.5 mg intervals to a dose that reduces chorea • Patients requiring > 50 mg should be genotyped for (PM) or extensive metabolizer (EM) of CYP2D6; max daily dose for PM is 50 mg divided into 2 doses of 25 mg; max daily dose for EM is 100 mg with a single dose of no more than 37.5 mg |
• Dose can be titrated by 6 mg/day to a dose that reduces chorea; max 48 mg/day (24 mg twice daily) • If switching from tetrabenazine, discontinue tetrabenazine and initiate deutetrabenazine the following day • Max dose for PM of CYP2D6 is 36 mg/day (18 mg twice daily) |
| Precautions |
• Sedation: May impair cognitive functions • QTc prolongation: Avoid in congenital long QT syndrome and/or arrhythmias that are associated with QTc prolongation |
• Do not exceed 50 mg/day (25 mg twice daily) when used with strong CYP2D6 inhibitors • Discontinue use if neuroleptic malignancy and/or extrapyramidal disorder occurs • Reduce dose or discontinue use if parkinsonism, restlessness, and agitation occurs • QTc prolongation: Not recommended to use with other QTc prolonging medications • Sedation: May impair cognitive functions |
• Reduce dose or discontinue use if parkinsonism, restlessness, and agitation occurs • Discontinue use if neuroleptic malignancy occurs • Sedation: May impair cognitive functions |