Procarbazine

An oral chemotherapy medicine, FDA-approved with other anticancer drugs for stage III and IV Hodgkin's disease.

psilodex.org/m/procarbazine · 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: ~10 min; Approximate, in adults. Source under Interaction below.

Named in state rules?

Not namedColorado

Not namedOregon

PendingNew Mexico

Cite asPsilodex, “Procarbazine”, v2026.10.05. psilodex.org/m/procarbazine

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

Stage III and IV Hodgkin's disease (with other anticancer drugs, MOPP regimen)

Sources [1]

Other safety

The label warns of bone marrow suppression and a disulfiram-like reaction with alcohol.

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

Sources [1]

01 Interaction with psilocybin

Not studied with psilocybin; related enzyme-blocking (MAO) drugs weakened psychedelic effects and raised psilocybin's blood pressure effects.

Detail No psilocybin data exist for procarbazine. Its label states it exhibits some monoamine oxidase (MAO) inhibitory activity, with tyramine food and sympathomimetic (stimulant) interactions. Human data come from other MAOIs: with LSD, chronic MAOI use was associated with a decreased subjective response (Bonson & Murphy 1996). Psilocybin mushrooms taken during phenelzine produced no noticeable subjective effects (Barnett 2024, as summarized in Tap 2025). In lab studies, one group found MAO-A formed only small amounts of 4-HIAA from psilocin (psilocybin's active form) (Thomann 2024). Another group estimated that MAO-A accounts for about 81% of psilocin's Phase I liver metabolism (Chen 2025). About a third of a psilocybin dose is excreted as 4-HIAA (Thomann 2024). So MAO inhibition may raise psilocin exposure. Class data on blood pressure: tranylcypromine increased psilocybin's blood-pressure and pupil effects in a small controlled study (Vojtěchovský 1968). One case report describes a hypertensive emergency (dangerously high blood pressure) with myocardial infarction (heart attack) (Barnett 2024). Also, the label also warns of CNS depression with other depressants and a disulfiram-like reaction with alcohol. Sources [1][2][3][4][5][6][7]

Human data with psilocybin: No data on this medication itself; related drugs studied (see text)
Half-life: ~10 min (IV) (FDA label, checked 2026-10-04) Parent drug after intravenous injection; oral capsule data not given.

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

2 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]
MAO inhibition: Inhibits monoamine oxidase, the enzyme that breaks down serotonin and other monoamines. MAO also helps clear psilocin, so it can change how strong and how long the psilocybin effect is, and it raises serotonin levels. Sources [1]

03 State rules

Plain-language summary · official text governs

CO4 CCR 755-1

Not named

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

None linked

No condition named in state rules is linked to this medication.

05 Sources

MATULANE (procarbazine) capsules (Leadiant) · FDA label (DailyMed) — MAO inhibition: Warnings "Because Matulane exhibits some monoamine oxidase inhibitory activity, sympathomimetic drugs, tricyclic antidepressant drugs (eg, amitriptyline HCI, imipramine HCI) and other drugs and foods with known high tyramine content" | Sedating or CNS depressant: Warnings "To minimize CNS depression and possible potentiation, barbiturates, antihistamines, narcotics, hypotensive agents or phenothiazines should be used with caution." | Clinical Pharmacology "After intravenous injection, the plasma half-life of procarbazine is approximately 10 minutes."
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."
Bonson KR, Murphy DL. Alterations in responses to LSD in humans associated with chronic administration of tricyclic antidepressants, monoamine oxidase inhibitors or lithium. Behav Brain Res 1996;73:229–233.
Barnett BS, Koons CJ, Van den Eynde V, et al. Hypertensive emergency secondary to combining psilocybin mushrooms, extended release dextroamphetamine-amphetamine, and tranylcypromine. J Psychoactive Drugs 2024;57(3):297–303.
Vojtěchovský M, Hort V, Šafratová V. Influence of MAO inhibitors on psilocybine induced psychosis. Activitas Nervosa Superior 1968;10(3):278–279 (via Tap 2025).
Tap SC, Thomas K, Páleníček T, et al. Concomitant use of antidepressants and classic psychedelics: a scoping review. J Psychopharmacol 2025. — Summary table, Barnett et al. (2024): phenelzine + nortriptyline dose "No (serious) AEs"; subjective effects at both doses "Complete absence of acute subjective effects." Bonson & Murphy row: "MAOIs were associated with decreases in subjective LSD response."
Chen J, Wang Z, Yong CY, et al. Elucidating the Phase I metabolism of psilocin in vitro. Arch Toxicol 2025;99(3):1085–1094. — Abstract: "MAO-A-mediated hepatic clearance of psilocin ... accounting for 80.9% of the total hepatic metabolism of psilocin" "MAO-A primarily contributed to the Phase I metabolism of psilocin."

Record history

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

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