Tetrabenazine

A VMAT2 inhibitor, FDA-approved for chorea associated with Huntington's disease; also used off-label for other movement disorders.

psilodex.org/m/tetrabenazine · data v2026.10.05

Clinical contraindication: None listed; No label contraindication covering psilocybin was found. This is not a finding that the combination has been shown to be without risk.
Psilocybin evidence: No psilocybin data
Half-life: ~5–7 h; Approximate, in adults. Source under Interaction below.

Named in state rules?

Not namedColorado Condition rules (3)

Not namedOregon

PendingNew Mexico

Cite asPsilodex, “Tetrabenazine”, v2026.10.05. psilodex.org/m/tetrabenazine

Clinical data and state rules are separate facts. Both are shown; neither is a decision.

What it is used for

FDA status

FDA-approved

FDA-approved for

Chorea (involuntary movements) of Huntington's disease

Sources [1]

Other safety

The label contraindicates use with MAOIs (or within 14 days), reserpine, deutetrabenazine or valbenazine, and in hepatic impairment or active suicidality.

About the medication itself, separate from any interaction with psilocybin.

Sources [1]

01 Interaction with psilocybin

Not studied with psilocybin; it depletes serotonin and dopamine, so a stronger or weaker response is possible. Separately, its label warns of depression and suicidality.

Detail Its effect on psilocybin is unknown. VMAT2 inhibition (emptying nerve-cell chemical stores) depletes monoamine stores, which may change the response in either direction. Its active metabolites are CYP2D6 substrates (broken down by this liver enzyme). CYP2D6 also metabolized psilocin in lab studies (Thomann 2024). Also, its label warns of depression and suicidality (boxed warning), sedation and QT prolongation (a heart-rhythm change). It also warns of orthostatic hypotension (blood pressure drop on standing) and NMS (neuroleptic malignant syndrome), and contraindicates MAOIs. Sources [1][2]

Human data with psilocybin: No psilocybin data; based on how it works and its label
Half-life: ~5–7 h (active metabolites) (FDA label, checked 2026-10-04) α-HTBZ ~7 h, β-HTBZ ~5 h.

Evidence types on this record

No psilocybin dataNo psilocybin data: no human data with psilocybin or another classic psychedelic; the text draws on the medication's own pharmacology and its label or reference facts

02 Pharmacology relevant to psilocybin

4 listed · counted on reports

Sedating or CNS depressant: Slows the central nervous system: drowsiness, slower reactions and impaired coordination, and slowed breathing at high doses. Effects add with other sedating substances. Sources [1]
Lowers blood pressure or causes orthostasis: Lowers blood pressure, or causes a drop on standing (orthostasis) that can bring dizziness or fainting. Sources [1]
Psychiatric reactions: The label or source warns of psychiatric effects such as psychosis, mania, hallucinations, suicidal thoughts or severe mood or behavior changes. Psilocybin can also bring up strong emotions, so these warnings are relevant to screening. Sources [1]
QT-prolonging: Lengthens the QT interval on an ECG, a measure of the heart’s electrical recovery between beats. A long QT raises the risk of a dangerous heart rhythm, more so with other QT-prolonging drugs or low potassium or magnesium. Sources [1]

03 State rules

Plain-language summary · official text governs

CO4 CCR 755-1

Not namedCondition rules (3)

No provision names this medication or its class.

Colorado · checked 2026-10-04

OROAR 333-333

Not named

No provision names this medication or its class.

Oregon · checked 2026-10-04

NM7.35.3 NMAC (proposed)

Pending

New Mexico's clinical rules (proposed 7.35.3 NMAC) are not final. No provision naming this medication has been found.

New Mexico · checked 2026-10-04

04 Conditions to ask about

Screening items in state rules

This medication is usually taken for a condition. State rules screen for some conditions directly, so the medication is a prompt to ask about them. Confirm with the participant; never assume a condition from the medication.

Huntington's disease (severe chronic illness)
- CO 2.5(A)(2) · Clinical Facilitator licensees
- CO 6.16(F)(2)(a) · Facilitators without a clinical facilitator license
- CO 6.16(F)(1) · All licensees

05 Sources

XENAZINE (tetrabenazine) tablets (Lundbeck) · FDA label (DailyMed) — Psychiatric reactions: Boxed Warning "XENAZINE can increase the risk of depression and suicidal thoughts and behavior (suicidality) in patients with Huntington's disease." | Sedating or CNS depressant: 5.7 "Sedation is the most common dose-limiting adverse reaction of XENAZINE." | QT-prolonging: 5.8 "XENAZINE causes a small increase (about 8 msec) in the corrected QT (QTc) interval." | Lowers blood pressure or causes orthostasis: 5.9 "XENAZINE induced postural dizziness in healthy volunteers receiving single doses of 25 or 50 mg." | 12.3 "α-HTBZ, β-HTBZ and 9-desmethyl-β-DHTBZ have half-lives of 7 hours, 5 hours and 12 hours respectively."
Thomann J, Kolaczynska KE, Stoeckmann OV, et al. In vitro and in vivo metabolism of psilocybin’s active metabolite psilocin. Front Pharmacol 2024;15:1391689. — Abstract: "recombinant CYP2D6 and CYP3A4 enzymes metabolized nearly 100% and 40% of psilocin, respectively." "MAO-A transformed psilocin into minimal amounts of 4-HIAA and 4-HTP." "In conclusion, MAO-A, CYP2D6, and CYP3A4 are involved in psilocin's metabolism." Introduction: "Around 33% of a psilocybin dose is renally excreted as 4-HIAA."

Record history

v2026.10.02First published.
2026-10-04Last reviewed against its sources.

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