RESEARCH MONOGRAPH · KDC-MN-218

Imipramine

May 9, 2026 Kodiac biolabs Research Revised May 30, 2026 3 min read

Our opinion on this compound

79/100

The first antidepressant. Historic, still on label, mostly relevant now for nocturnal enuresis and pharmacology history

Imipramine is the molecule that essentially created modern psychopharmacology. Geigy chemist Walter Schindler synthesized it in 1951 as a chlorpromazine analog, Roland Kuhn at the Munsterlingen psychiatric hospital observed antidepressant effects in 1956 while testing it as a sedative, and the 1958 publication kicked off the entire monoamine hypothesis of depression. The history alone makes it interesting. The pharmacology, though, is honestly more useful as a research tool than as a clinical drug in 2026.

Receptor profile is the prototypical tertiary-amine TCA: SERT and NET inhibition roughly balanced, potent H1 antagonism, solid muscarinic anticholinergic activity, 5-HT2A antagonism, alpha-1 blockade, and sodium channel effects similar to amitriptyline. The N-desmethyl metabolite (desipramine) is significantly more NET-selective and is itself an approved antidepressant, which means imipramine pharmacokinetically delivers both molecules during chronic dosing.

The efficacy data is enormous and historical: thousands of trials, decades of clinical use, the original active comparator in pretty much every antidepressant trial through the 80s. For MDD it's roughly comparable to other TCAs and modestly more effective than SSRIs in some severity strata (the Anderson and Tomenson meta-analyses showed TCA advantage in hospitalized severe depression that doesn't fully replicate in outpatient cohorts). The acceptability profile is class-typical TCA, which is to say poor.

Where imipramine has a unique residual clinical indication is nocturnal enuresis in children, where low doses (10-50 mg) reduce bedwetting frequency through mechanisms that include central modulation of bladder reflex and probably some anticholinergic peripheral effects. This indication has been around since the 60s and persists despite the SSRI revolution, partly because the alternatives (desmopressin, behavioral alarms) have their own drawbacks. The pediatric safety profile in this context is reasonably well-established for short-term use.

For research applications imipramine is the historical reference TCA and remains a useful tool compound for studying mixed SERT / NET / multi-receptor pharmacology, particularly in animal models where direct historical comparability to the original antidepressant literature matters. It's not the cleanest pharmacological probe in any single mechanism, but it's the reference standard for the polypharmacology of the antidepressant class.

Sourcing is trivial, generic for decades, USP / EP standards everywhere. Historical importance plus continuing niche utility for enuresis plus tool-compound value gives it real staying power.

Evidence: 90
Mechanism: 85
Reliability: 78
Safety: 60
Sourcing: 92
Value: 85
Signal: 65
Staying power: 75

Plain-language summary Intrigue 60 / 100

Imipramine is historically the most important antidepressant ever made: Roland Kuhn at Geigy noticed in 1958 that this antihistamine candidate unexpectedly lifted depressed patients' moods, which kicked off the entire monoamine theory of depression and the modern era of psychiatric pharmacology. Mechanically it blocks the serotonin and norepinephrine pumps in roughly balanced fashion, while also blocking acetylcholine, histamine, and alpha-1 adrenergic receptors as side activities. Today it sees mostly historical and academic use, plus a niche role in nocturnal enuresis (bedwetting) in children. The cardiac sodium channel block makes overdose lethal, which is one reason SSRIs displaced it once they became available. 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.

Tricyclic antidepressant (tertiary amine; first synthetic antidepressant)

The first synthetic antidepressant; the parent compound of the TCA class and the historical reference for monoamine theory of depression.

Abstract

Imipramine (3-(10,11-dihydro-5H-dibenzo[b,f]azepin-5-yl)-N,N-dimethylpropan-1-amine; CAS 50-49-7; molecular formula C19H24N2; molecular weight 280.41) is a dibenzazepine tertiary amine TCA developed at Geigy by Roland Kuhn in 1958, the first synthetic compound demonstrated to relieve depressive symptoms in clinical trial. The historical observation underpinned the catecholamine hypothesis of depression and launched modern psychopharmacology. SERT and NET affinities are balanced (SERT Ki approximately 1 nM, NET Ki approximately 21 nM); the active metabolite desipramine is a NET-preferring secondary amine. Off-target activity parallels amitriptyline: muscarinic, H1, alpha-1, and sodium channel block. Plasma half-life is 11 to 25 hours; metabolism is via CYP2D6 and CYP2C19. Approved for major depressive disorder; clinical use today focuses on enuresis (bedwetting) in children (low-dose for anticholinergic and alpha-1 effects on bladder) and panic disorder. The TCA cardiotoxicity profile is the principal limitation. Used as the historical reference TCA and the prototype monoamine reuptake inhibitor in pharmacology.

Mechanism of action

Balanced SERT/NET inhibition with anticholinergic, antihistaminergic, alpha-1, and sodium channel block. Historical reference compound for monoamine theory of depression.

Reported research dose ranges

Reported research dose ranges in the literature.

References

Kuhn R. The treatment of depressive states with G 22355 (imipramine hydrochloride). Am J Psychiatry 1958.
Bryson HM, Wilde MI, et al. Imipramine. A review of its pharmacological properties and therapeutic use. Drugs 1996.
Owens MJ, et al. Second-generation SSRIs: human monoamine transporter binding profile. Biol Psychiatry 2001.

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KDC-MN-218

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Imipramine

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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