Tricyclic antidepressant (chlorinated tertiary amine)

Plain-language summaryIntrigue 64 / 100

Clomipramine (Anafranil) is a tricyclic antidepressant with one chlorine atom added to imipramine, a small change that flips the selectivity sharply toward serotonin. It is in fact the most potent serotonin reuptake blocker in the entire tricyclic class, with affinity rivaling modern SSRIs. The active leftover after liver metabolism then shifts steady-state activity back toward norepinephrine, so the drug ends up doing both jobs over a 24-hour period. It is the only tricyclic with FDA approval for OCD and remains a third-line option for severe OCD when SSRIs fail. The usual tricyclic burdens (sedation, anticholinergic effects, cardiac risk in overdose) all apply. 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 Kodiac editorial, not peer-reviewed.

Our opinion on this compoundEstablished workhorse

45/100

The gold-standard TCA for OCD research but a closed mechanistic frontier with deep evidence and low novelty

Look, clomipramine is one of those compounds where the resume is genuinely impressive but the research horizon has mostly closed. Developed at Geigy in the early 1960s and FDA-approved in 1989 specifically for OCD, it’s been the clinical anchor in treatment-resistant obsessive-compulsive disorder for over three decades. The SERT Ki of roughly 0.28 nM is remarkable for a TCA. Nothing else in the class touches it. And the parent/metabolite pharmacology has a quietly interesting wrinkle: clomipramine is SERT-dominant, but CYP3A4 and CYP2C19-driven demethylation produces N-desmethylclomipramine, a NET-preferring secondary amine, so at steady state you get dual monoaminergic coverage without deliberately engineering it. Thats a legitimately non-trivial pharmacokinetic story.

But none of that is new. The SERT mechanism was worked out decades ago. The OCD indication is mature to the point where the main clinical question is how it compares to SSRIs in treatment-resistant cases, and that question has been asked and partially answered many times over. The off-target burden, muscarinic block, H1 antagonism, alpha-1 and sodium channel activity, makes clomipramine a dirty probe for anything requiring clean SERT signal. If you need a SERT-selective tool in a model system, you’re reaching for citalopram or escitalopram, not this.

Where clomipramine still earns real bench value is as a reference standard in OCD neurobiology. The serotonin hypothesis of OCD is actually more complex than it sounds: there’s ongoing work around 5-HT2A contributions, orbitofrontal circuit modulation, and the genuinely unresolved question of why SERT saturation matters more in OCD than in other anxiety-adjacent disorders. Clomipramine is the clinical anchor for those comparisons. We also think the cataplexy research angle is underappreciated; it remains one of the few compounds with both mechanistic plausibility and real clinical signal in narcolepsy-associated cataplexy, and that’s a small but legitimate research context.

Honestly, the evidence quality here is as high as it gets. Decades of RCTs, multi-site replication, clear regulatory validation. But thats almost the problem: when evidence is this mature, the interesting questions are mostly downstream of the compound, not about it. What we don’t like about recommending this as a primary research focus is that a bench investigator picking it up today is almost certainly asking a comparative or clinical question, not a mechanism-frontier question. That makes it a solid reference tool and a useful historical benchmark. It’s not where serious research resources go to find new answers.

Novelty: 20
Mechanism promise: 25
In-category differentiation: 45
Evidence quality: 75
Translational signal: 70
Research bench value: 55

Rationale Clomipramine scores high on evidence quality and translational signal (FDA-approved, decades of replicated OCD RCTs, reference-standard status) but low novelty and mechanism scores drag the overall down hard; the SERT story is fully mature and the off-target burden makes it a poor clean probe for mechanism work despite its unique clinical niche.

Tricyclic antidepressant (chlorinated tertiary amine)

A chloro-substituted TCA with the most potent SERT inhibition in the class; the only TCA with FDA approval for OCD.

Abstract

Clomipramine (3-(3-chloro-10,11-dihydro-5H-dibenzo[b,f]azepin-5-yl)-N,N-dimethylpropan-1-amine; CAS 303-49-1; molecular formula C19H23ClN2; molecular weight 314.85) is a 3-chloro-substituted analog of imipramine developed at Geigy and approved by the FDA in 1989 under the trade name Anafranil. The chloro substitution shifts transporter selectivity sharply toward SERT (SERT Ki approximately 0.28 nM, the most potent in the TCA class; NET Ki approximately 38 nM). The active metabolite N-desmethylclomipramine (formed via CYP3A4/CYP2C19) is a NET-preferring secondary amine, producing balanced steady-state monoaminergic activity from a SERT-dominant parent. Off-target activity parallels other tertiary amine TCAs: muscarinic, H1, alpha-1, and sodium channel block. Plasma half-life is 19 to 37 hours. The compound is the only TCA with FDA approval for obsessive-compulsive disorder, an indication where the SSRI class typically requires higher doses; clomipramine remains a benchmark in treatment-resistant OCD. Used as the reference SERT-potent TCA in mechanism studies.

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The full reference document covers compound identification, discovery and developmental history, mechanism of action, pharmacokinetics, sourcing and quality verification, and a curated reference list. Embedded inline below; download for offline reading.

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Tag: Tricyclic antidepressant (chlorinated tertiary amine)

Clomipramine

Abstract

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