Educational only — not medical advice. If you’re in crisis or thinking about suicide: call or text 988 (U.S.) or your local emergency number. Support resources. Under construction and review—see the updates log.

trimipramine

Adjunctive therapy

Brand: Surmontil

Published 2026-03-24 · Last reviewed 2026-03-31 · 4 references

Content sourced from FDA labeling (DailyMed) and peer-reviewed literature.

Print sheet Review evidence

At a glance

Class: Adjunctive therapy·Typical dose: Label dosing is individualized. Outpatient adults: typically start 75 mg/day in divided doses, increasing to 150 mg/day; maximum outpatient dose is 200 mg/day. Hospitalized adults: start 100 mg/day, with a maximum of 250–300 mg/day. Adolescent and geriatric patients: start 50 mg/day with a maximum of 100 mg/day. Once at maintenance dose, the total daily amount can often be given as a single bedtime dose (label).·Half-life: Single-dose range 23–24 h·TDM range: 150–300 ng/mL·LAI available: No

Class: Adjunctive therapy
Typical dose: Label dosing is individualized. Outpatient adults: typically start 75 mg/day in divided doses, increasing to 150 mg/day; maximum outpatient dose is 200 mg/day. Hospitalized adults: start 100 mg/day, with a maximum of 250–300 mg/day. Adolescent and geriatric patients: start 50 mg/day with a maximum of 100 mg/day. Once at maintenance dose, the total daily amount can often be given as a single bedtime dose (label).
Half-life: Single-dose range 23–24 h
TDM range: 150–300 ng/mL
LAI available: No

Quick answers

What is trimipramine?: Trimipramine (brand Surmontil; generics) is a tricyclic antidepressant (TCA) indicated for the relief of symptoms of depression. It is often characterized by a sedating, anxiety-reducing profile compared with more “activating” TCAs (label/clinical).
What is Surmontil?: Surmontil is a brand name for trimipramine.
What is Surmontil (trimipramine) used for?: Label indications include: Depression.
What drug class is Surmontil (trimipramine)?: Tricyclic Antidepressant.
What is the mechanism of action of Surmontil (trimipramine)?: Tertiary-amine tricyclic antidepressant (TCA) with a sedating/anxiolytic clinical profile; mixed monoamine effects plus strong H1/α1/muscarinic antagonism.
What strengths does Surmontil (trimipramine) come in?: Oral capsules (label): 25 mg, 50 mg, 100 mg.

General information

Trimipramine (brand Surmontil; generics) is a tricyclic antidepressant (TCA) indicated for the relief of symptoms of depression. It is often characterized by a sedating, anxiety-reducing clinical profile compared with more “activating” TCAs (label/clinical).

TCAs have a narrow therapeutic index and are dangerous in overdose; this overdose risk is one reason they are generally positioned after SSRIs and SNRIs in major depressive disorder guidelines (APA/CANMAT/clinical).

In serious mental illness, sedating antidepressants can be considered when insomnia and anxious distress are prominent, but trimipramine requires careful balancing against anticholinergic and orthostatic harms, especially in older adults and polypharmacy (clinical).

Therapeutic drug monitoring (TDM) is commonly used with TCAs. AGNP guideline therapeutic reference range for trimipramine is 150–300 ng/mL (Hiemke 2018).

The compare view, trimipramine evidence feed, and trimipramine print page support documentation of why a sedating TCA was selected and how safety monitoring is planned.

U.S. approvals

Depression

Formulations & strengths

Oral capsules (label): 25 mg, 50 mg, 100 mg.

Generic availability

Generic capsules available; brand Surmontil appears intermittently in U.S. listings.

Trimipramine is used less frequently than SSRIs/SNRIs because of anticholinergic burden, falls risk, and overdose lethality. When it is selected, follow-up focuses on sedation/functional safety, bowel and bladder symptoms, and ECG/TDM planning to avoid preventable toxicity.

View labelExact

Mechanism of action

Refer to the Glossary entry on Neurotransmitters for background on receptor systems involved in serious mental illness.

As a TCA, trimipramine has mixed monoamine effects and antagonizes H1, muscarinic, and α1-adrenergic receptors, which contribute to sedation, constipation/urinary retention, and Orthostatic hypotension (mechanism/class).

Sodium-channel blockade is a class effect that contributes to QRS widening and ventricular arrhythmia risk in overdose (class warning).

Mixed monoamine effects with prominent H1/M1/α1 antagonism (sedation, anticholinergic effects, orthostasis).

Metabolism & pharmacokinetics

Metabolized hepatically; CYP2D6 and CYP3A4 variability and drug interactions can alter exposure (Hiemke 2018/class).
AGNP guideline elimination half-life is ~23–24 hours; an active metabolite (N-desmethyltrimipramine) contributes to exposure (Hiemke 2018).
Because TCAs distribute widely and bind proteins, clinical observation is prioritized over early serum levels in suspected overdose (clinical).

Dosing & administration

Label dosing is individualized. Outpatient adults: typically start 75 mg/day in divided doses, increasing to 150 mg/day; maximum outpatient dose is 200 mg/day. Hospitalized adults: start 100 mg/day, with a maximum of 250–300 mg/day. Adolescent and geriatric patients: start 50 mg/day with a maximum of 100 mg/day. Once at maintenance dose, the total daily amount can often be given as a single bedtime dose (label).
ECG changes, orthostasis, and anticholinergic burden are monitored during titration, especially in hospitalized patients and older adults (label/clinical).
TDM: the AGNP therapeutic reference range is 150–300 ng/mL. Levels are commonly obtained after steady state or when response/toxicity is unclear in the setting of interactions (Hiemke 2018/clinical).
When discontinuing after longer courses, gradual tapering is commonly used; abrupt cessation after prolonged therapy may produce nausea, headache, and malaise (label/clinical).

Monitoring & labs

Baseline and follow-up ECG planning in patients with cardiac history, older age, electrolyte disturbance risk, or multiple QT-active drugs (clinical).
TDM after steady state or after major interaction changes when response is partial or toxicity is suspected (Hiemke 2018/clinical).
Orthostatic vitals, falls risk, and anticholinergic burden (bowel and bladder symptoms, cognition), especially in older adults (clinical).
Suicidality and mood switching surveillance early in treatment and after dose changes, particularly in young adults and bipolar-spectrum illness (label/clinical).

Monitoring for a sedating TCA focuses on safety (falls risk, anticholinergic burden, ECG changes) while ensuring adequate exposure when response is incomplete (TDM).

Adverse effects

FDA boxed warnings

Boxed warning: antidepressants increase the risk of suicidal thoughts/behaviors in children, adolescents, and young adults.

Common side effects (≥10%)

Sedation and daytime impairment: Sedation, grogginess, and impaired balance can occur; falls risk is higher in older adults and with other sedatives (label/clinical).
Anticholinergic effects: Anticholinergic side effects (constipation, urinary retention, blurry vision, cognitive slowing) are common limiting adverse effects (label/clinical).
Orthostasis: Orthostatic hypotension and dizziness can occur during titration and with polypharmacy (label/clinical).
Weight changes: Weight gain or weight loss can occur with TCAs; monitoring is individualized to baseline risk (label/clinical).

Other notable effects

Cardiac conduction changes and arrhythmias are key safety issues for the TCA class; ECG monitoring is often used when risk is elevated (clinical).
Seizure threshold reduction can occur at higher exposures or with pro-convulsant co-medications (class effect).
Serotonin syndrome can occur when TCAs are combined with other serotonergic agents, particularly during initiation and dose increases (label/class).
Mood switching can occur in bipolar-spectrum illness; monitoring for Mania/Hypomania is commonly coordinated when treating depressive episodes (clinical).
Angle-closure glaucoma can be triggered by pupillary dilation from anticholinergic activity in patients with anatomically narrow angles who have not had an iridectomy (label).
Overdose toxicity (coma, seizures, ventricular arrhythmias) is a major reason TCAs are used selectively; safe-storage counseling is part of routine prescribing (clinical).

Interactions

MAOIs intended to treat psychiatric disorders are contraindicated concurrently and within 14 days, including linezolid and intravenous methylene blue; washout applies in both directions (label).
Contraindicated during the acute recovery period after myocardial infarction (label).
CYP2D6 inhibitors — including fluoxetine, paroxetine, quinidine, sertraline, cimetidine, phenothiazines, propafenone, and flecainide (label) as well as bupropion (clinical) — can raise TCA exposure; dose adjustment and/or TDM are common mitigation strategies.
Additive sedation and respiratory risk can occur with alcohol, benzodiazepines, opioids, and sedating antipsychotics (clinical).
Other anticholinergic medications (some antipsychotics, antihistamines) can compound constipation, urinary retention, and delirium risk (clinical).
QT- and conduction-active drugs increase cumulative arrhythmia risk; medication reconciliation typically includes OTC cold/sleep products (clinical).

Other useful information

If sedation is a major target symptom (insomnia comorbidity), clinicians often compare alternatives with clearer evidence and lower anticholinergic burden before escalating TCA doses (clinical).
When depressive symptoms occur in bipolar disorder, antidepressants are commonly paired with a mood stabilizer and monitored for mood switching; see the bipolar disorder hub for longitudinal care pathways.
For older adults, medication review that reduces additive anticholinergic and sedative burden is often higher yield than adding multiple “side-effect” medications (clinical).

References

Related hubs:SMI toolkit·Support resources