Is Rexulti affected by genetics?

Yes — the active ingredient is metabolized by a gene known to vary between individuals.

Relevant genes: CYP2D6

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Rexulti is affected by pharmacogenetics through the CYP2D6 gene. Your genotype for this gene can change how your body processes Rexulti, which can affect both how well it works and how well you tolerate it. The strongest evidence level on this page is Moderate, based on CPIC or FDA guidelines.

What's in Rexulti

brexpiprazole affected by CYP2D6

Affected by CYP2D6 · FDA · Moderate evidence

Read the full brexpiprazole genetics guide →

Brexpiprazole phenotype recommendations

Published guidance from FDA on how brexpiprazole should be dosed or substituted based on your CYP2D6 phenotype.

Phenotype	What it means	Recommendation	Evidence
Ultrarapid Metabolizer CYP2D6	Your body processes brexpiprazole faster than most people, but there is no specific FDA guidance for your genotype. The standard dose is typically used.	FDA Initiate therapy with recommended starting dose.	—
Normal Metabolizer CYP2D6	Your body processes brexpiprazole at a normal rate. The standard dose should work as expected.	FDA Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2D6	Your body processes brexpiprazole slightly slower than average, but there is no specific FDA guidance for your genotype. The standard dose is typically used.	FDA Initiate therapy with recommended starting dose.	—
Poor Metabolizer CYP2D6	Your body breaks down brexpiprazole much more slowly than normal, causing the drug to build up in your system. A lower dose is recommended to reduce the risk of side effects.	FDA Reduce the dose as recommended by FDA labeling due to higher drug levels.	Moderate
Indeterminate CYP2D6	The impact of your genotype on response to this drug is unknown	FDA Initiate therapy with recommended starting dose.	—
Not available CYP2D6	The impact of your genotype on response to this drug is unknown	FDA Initiate therapy with recommended starting dose.	—

Source: FDA

The gene behind the guidance

CYP2D6 Cytochrome P450 2D6

CYP2D6 is the most clinically important pharmacogene. It metabolizes around a quarter of all prescription drugs, including many antidepressants, opioids, and stimulants. The gene is unusually variable: roughly 7 percent of people are poor metabolizers (they barely activate CYP2D6), and another 1 to 3 percent are ultrarapid metabolizers (their enzyme is overactive).

For most CYP2D6 drugs, poor metabolizers feel stronger effects and more side effects at standard doses, while ultrarapid metabolizers may feel almost nothing. For prodrugs like codeine, the relationship flips: poor metabolizers feel less effect because they can't activate the drug.

See all drugs affected by CYP2D6 →

Browse the full drug-class: Antipsychotics.

Related medications

Find out how your genetics affect Rexulti

This page describes the general pharmacogenetics. A Gene2Rx report analyzes your own DNA to tell you which metabolizer group you fall into, across every medication.

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Informational only — not medical advice. Pharmacogenetic guidance describes population-level patterns; your individual response depends on many factors. Never start, stop, or change a medication without talking to your prescribing clinician.