Imipramine

證據等級: L5

預測適應症: 10 個

Imipramine: From Depression to Attention Deficit-Hyperactivity Disorder

One-Sentence Summary

Imipramine is a first-generation tricyclic antidepressant (TCA) with a long-established history in treating major depressive disorder and related conditions. The TxGNN model predicts it may be effective for Attention Deficit-Hyperactivity Disorder (ADHD), with 1 registered clinical trial and 20 publications currently supporting this direction.

Quick Overview

Item	Content
Original Indication	Depression (established tricyclic antidepressant; no Singapore registration on record)
Predicted New Indication	Attention Deficit-Hyperactivity Disorder (ADHD)
TxGNN Prediction Score	99.90%
Evidence Level	L3
Singapore Market Status	✗ Not Marketed
Number of Registrations	0
Recommended Decision	Hold

Why is This Prediction Reasonable?

Detailed mechanism of action data is not available in the current evidence pack. Based on known pharmacology, Imipramine is a prototypical tricyclic antidepressant that simultaneously inhibits the norepinephrine transporter (NET) and the serotonin transporter (SERT) at the presynaptic membrane, raising synaptic concentrations of both monoamines. It also exerts antagonism at histamine H₁, muscarinic, and alpha-1 adrenergic receptors, accounting for much of its side-effect profile.

The connection to ADHD is mechanistically plausible. NET inhibition in the prefrontal cortex enhances catecholamine signalling, thereby improving attentional regulation and executive function — the same pathway exploited by atomoxetine (Strattera), the first FDA-approved non-stimulant ADHD agent. Imipramine is essentially a non-selective predecessor to atomoxetine in this regard. Its additional SERT component may confer benefit in managing the mood and anxiety comorbidities that frequently accompany ADHD.

Historically, imipramine was among the first pharmacological alternatives explored when stimulants (methylphenidate, dextroamphetamine) failed in paediatric ADHD, dating back to the 1980s. Multiple clinical studies and safety reviews confirm measurable therapeutic effects, particularly in stimulant-non-responsive children. However, the evidence base rests primarily on older observational studies and narrative reviews rather than modern, prospective Phase 2/3 randomised controlled trials, and imipramine has been largely superseded by more selective agents with better tolerability profiles.

Clinical Trial Evidence

Trial Number	Phase	Status	Enrollment	Key Findings
NCT03220308	N/A	Completed	103	8-week mindfulness group training for children (8–16 years) with ADHD combined with mindful parenting vs. care-as-usual; intervention is entirely non-pharmacological and not directly relevant to imipramine pharmacotherapy

Note: The sole registered clinical trial identified for this drug–disease pair evaluated a non-drug intervention. No registered clinical trial directly investigating imipramine for ADHD was identified.

Literature Evidence

PMID	Year	Type	Journal	Key Findings
18304665	2008	Clinical Study	Int J Psychophysiology	Imipramine significantly normalised EEG profiles in ADHD children who were poor responders to stimulants, demonstrating clinical utility as a second-line pharmacotherapy
6849467	1983	Clinical Report	Am J Psychiatry	Early clinical report directly addressing imipramine use in attention deficit disorder, establishing the historical basis for this indication
9465283	1996	Clinical Study	Clin EEG	Prolonged auditory and visual P300 latency predicted poor response to imipramine in ADHD children; provides potential biomarker for patient selection
32982805	2020	Meta-Review	Frontiers in Psychiatry	Systematic meta-review of antidepressants (including imipramine) in children and adolescents across multiple psychiatric disorders including ADHD; assessed efficacy, tolerability, and suicidality risk
34002501	2021	Umbrella Review	World Psychiatry	Umbrella review of pharmacological, psychosocial, and brain stimulation interventions in children and adolescents with mental disorders; includes analysis of TCA-class agents for ADHD within a network meta-analytic framework
15794722	2005	Review	Expert Opinion on Drug Safety	Comprehensive safety review of non-stimulant ADHD agents; confirms imipramine and desipramine as potentially effective alternatives when stimulants are contraindicated or fail
17078784	2006	Clinical Study	Expert Review of Neurotherapeutics	P300 topography-guided treatment selection for ADHD; identifies imipramine alongside atomoxetine as effective norepinephrine reuptake inhibitors, confirming shared mechanistic class
10790990	1999	Treatment Review	Evid Rep Technol Assess	Systematic evidence review of short- and long-term effectiveness of pharmacological and non-pharmacological ADHD interventions in children and adults
2258453	1990	Retrospective Study	J Clin Psychopharmacology	Concomitant carbamazepine significantly reduced plasma imipramine concentrations in ADHD children despite higher doses; flags an important drug–drug interaction relevant to polypharmacy scenarios
2830919	1988	Biological Study	Biological Psychiatry	[³H]imipramine platelet binding parameters did not differ between ADHD children and healthy controls, nor were they altered by methylphenidate treatment; provides neurobiological context for serotonergic transporter involvement

Singapore Market Information

Imipramine is currently not registered or marketed in Singapore. No product licences are on record (total licences: 0). There are no approved brand-name products, dosage forms, or registered indications available for review.

Safety Considerations

Please refer to the package insert for safety information.

Class-level note for clinical teams: As a tricyclic antidepressant, imipramine carries class-wide risks that should be considered regardless of indication, including QTc prolongation and cardiac arrhythmia risk (particularly relevant in paediatric dosing), anticholinergic effects (urinary retention, constipation, dry mouth), lowered seizure threshold, and a narrow therapeutic index requiring plasma level monitoring. These are established TCA class effects, not data gaps.

Conclusion and Next Steps

Decision: Hold

Rationale: While imipramine has a mechanistically well-grounded connection to ADHD through NET/SERT inhibition — the same pathway exploited by the approved agent atomoxetine — the current evidence base consists of older observational studies, narrative reviews, and a single clinically irrelevant registered trial. The absence of a modern Phase 2/3 RCT, combined with the availability of safer and more selective alternatives (atomoxetine, methylphenidate), and imipramine's current non-marketed status in Singapore, does not support advancing this candidate without additional structured research.

To proceed, the following is needed:

Formal mechanism of action data from DrugBank or the package insert (currently flagged as a data gap)
A prospective Phase 2 RCT directly comparing imipramine to placebo or atomoxetine in ADHD using modern diagnostic criteria and validated outcome scales (e.g., ADHD-RS, Conners)
Cardiovascular safety monitoring plan (QTc, blood pressure, heart rate) given the TCA class profile — especially critical for any paediatric study
Singapore regulatory pathway assessment: registration strategy or Named Patient Programme evaluation if development is pursued locally
Systematic review or individual patient data meta-analysis of existing imipramine-ADHD studies to quantify effect size relative to current standard-of-care
Disclaimer

This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.