This section contains excerpted
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information on gene-based dosing recommendations. Neither this section nor other parts of this review contain the complete recommendations from the sources.
2017 Statement from the US Food and Drug Administration (FDA)
2.4 Dosage Adjustment in Poor CYP2D6 Metabolizers
In patients who are poor CYP2D6 metabolizers, the total daily dosage of deutetrabenazine should not exceed 36 mg (maximum single dose of 18 mg).
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5.3 QTc Prolongation
Tetrabenazine, a closely related VMAT2 inhibitor, causes an increase (about 8 msec) in the corrected QT (QTc) interval. A clinically relevant QT prolongation may occur in some patients treated with deutetrabenazine who are CYP2D6 poor metabolizers or are co-administered a strong CYP2D6 inhibitor.
For patients who are CYP2D6 poor metabolizers or are taking a strong CYP2D6 inhibitor, dose reduction may be necessary. The use of deutetrabenazine in combination with other drugs that are known to prolong QTc may result in clinically significant QT prolongations.
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8.7 Poor CYP2D6 Metabolizers
Although the pharmacokinetics of deutetrabenazine and its metabolites have not been systematically evaluated in patients who do not express the drug metabolizing enzyme, it is likely that the exposure to α-HTBZ and β-HTBZ would be increased similarly to taking a strong CYP2D6 inhibitor (approximately 3-fold).
Please review the complete therapeutic recommendations that are located here:
(1).
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The FDA labels specific drug formulations. We have substituted the generic names for any drug labels in this excerpt. The FDA may not have labeled all formulations containing the generic drug. Certain terms, genes and genetic variants may be corrected in accordance to nomenclature standards, where necessary. We have given the full name of abbreviations, shown in square brackets, where necessary.