RESEARCH MONOGRAPH · KDC-MN-230

Toloxatone

May 9, 2026 Kodiac biolabs Research Revised May 30, 2026 2 min read

Our opinion on this compound

44/100

Early reversible MAO-A inhibitor that mostly vanished and the literature trail is genuinely thin

Toloxatone is a reversible MAO-A inhibitor that was developed and marketed in France in the eighties as Humoryl, and outside of France it essentially never had a clinical life. The mechanism is straightforward selective reversible MAO-A inhibition through an oxazolidinone scaffold that doesn't show up in the other RIMAs.

Honestly the literature on this compound is thin enough that we want to hedge. The clinical trial data is mostly French-language, mostly from the eighties and nineties, and reproducibility-grade modern pharmacology isnt really there. Toloxatone was eventually withdrawn from the French market, mostly for commercial rather than safety reasons as far as we can tell, and the compound has basically dropped out of active research.

What we find interesting structurally is that the oxazolidinone scaffold is the same chemistry family that linezolid sits in. Linezolid is an antibiotic that famously has MAOI activity as a side effect, which has caused tyramine reaction problems when patients on linezolid eat aged cheeses. So toloxatone is in some sense the cleaner-pharmacology cousin of linezolids accidental MAOI activity, and that connection is occasionally useful for thinking about scaffold-mechanism relationships in oxazolidinones generally.

For research, toloxatone is mostly historical. If you specifically want an oxazolidinone-scaffold RIMA for SAR or selectivity work, this is the obvious starting point. If you just want a clean MAO-A probe, moclobemide is the better-characterized choice.

What we dont know enough about is the long-term safety profile beyond what the original French clinical data suggests. The withdrawal happened for reasons that aren't fully documented in sources we trust, and we'd want to see modern characterization before making strong claims.

Sourcing is the practical issue. Reference material exists but vendor selection is thin and per-gram costs run higher than the better-established RIMAs. HPLC validation is doable but you need to characterize what arrives.

Treat this as a thin-evidence historical compound. Interesting scaffold, not a working tool.

Evidence: 38
Mechanism: 65
Reliability: 45
Safety: 60
Sourcing: 45
Value: 40
Signal: 30
Staying power: 30

Plain-language summary Intrigue 38 / 100

Toloxatone (Humoryl) is a French reversible MAO-A inhibitor from Delalande, approved in France in 1984. Like moclobemide and pirlindole it can be displaced from the enzyme by dietary tyramine, which means patients can eat aged cheese without triggering a hypertensive crisis. The drug had a brief moment of relevance in French psychiatry but never spread to other markets, was not pursued for FDA approval, and was eventually discontinued in France in the 2000s as newer antidepressants displaced it. It is mostly of historical interest now, although it remains a useful research probe for MAO-A pharmacology because of its clean mechanism. Not stocked by Kodiac. This monograph is provided for research and educational reference.

Intrigue 0–100 blends mechanism novelty, evidence strength, and translational potential. Kodiac editorial, not peer-reviewed.

Reversible MAO-A inhibitor

A 5-(hydroxymethyl)oxazolidinone RIMA approved in France in 1984; an early-generation reversible inhibitor of MAO-A.

Abstract

Toloxatone (5-(hydroxymethyl)-3-(3-methylphenyl)oxazolidin-2-one; CAS 29218-27-7; molecular formula C11H13NO3; molecular weight 207.23) is an oxazolidinone RIMA developed at Delalande in France and approved there in 1984 under the trade name Humoryl. The compound is a reversible competitive MAO-A inhibitor with a clinical profile broadly comparable to moclobemide; selectivity for MAO-A over MAO-B is approximately 50-fold at therapeutic concentrations. Plasma half-life is approximately 2 hours; hepatic metabolism is the primary clearance pathway. Tyramine restriction is not required at clinical doses. Clinical efficacy in major depressive disorder was demonstrated in French trials but the drug never received approval outside France and clinical use has substantially declined. Used historically and as a reference oxazolidinone RIMA in mechanism studies.

Mechanism of action

Reversible competitive MAO-A inhibition. Oxazolidinone scaffold.

Reported research dose ranges

Reported research dose ranges in the literature.

References

Provost JC, et al. Toloxatone in the treatment of depression. Neuropsychobiology 1992.
Riederer P, et al. Reversible monoamine oxidase A inhibitors. CNS Drugs 1995.
Da Prada M, et al. From moclobemide to Ro 19-6327 and Ro 41-1049. J Neural Transm Suppl 1990.

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KDC-MN-230

The full reference document is provided strictly for research use only. It reports research dose ranges from the published literature, not instructions for use in humans or animals.

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Toloxatone

Abstract

Mechanism of action

Reported research dose ranges

References

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Abstract

Mechanism of action

Reported research dose ranges

References

Read the full monograph

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