Skip to main content

Imipramine

Imipramine is a tertiary-amine tricyclic antidepressant (TCA) with a broader urologic footprint than any other TCA — the only TCA with an FDA-approved urologic indication (temporary adjunctive therapy for childhood nocturnal enuresis in patients ≥ 6 years) and the TCA most often cited off-label for overactive bladder, stress urinary incontinence, mixed urinary incontinence, and — less often — as part of multimodal therapy for interstitial cystitis / bladder pain syndrome.[1][2][3] It lives in "legacy" not because it is obsolete — it remains the go-to TCA when enuresis fails desmopressin, alarms, and antimuscarinics[8] — but because its narrow therapeutic index, cardiotoxicity, and lethal overdose profile have pushed it behind modern antimuscarinics and β₃-agonists for most adult voiding indications.

For class-level pharmacology, comparative TCA selection, and imipramine's role alongside amitriptyline, nortriptyline, and doxepin, see the TCAs hub. For the serotonergic-adrenergic alternative with a cleaner cardiac profile, see SNRIs and Desmopressin (first-line for nocturnal enuresis and nocturnal polyuria).

Mechanism of Action — Why Imipramine Works in the Urinary Tract​

Imipramine's urologic effects are the convergent product of five mechanisms, which together explain why a single drug modulates storage, outlet resistance, and nocturnal urine output:

MechanismClinical effect
Muscarinic antagonism↓ detrusor contractility, ↑ bladder capacity, ↓ uninhibited contractions[2][4]
NE + 5-HT reuptake inhibition↑ sympathetic tone at bladder neck / proximal urethra → ↑ outlet resistance; central modulation of the micturition reflex at spinal and supraspinal levels[2][3][4]
Direct detrusor smooth-muscle inhibitionInhibits bethanechol- and BaCl₂-induced contractions independent of muscarinic blockade[2]
Central arousal / sleep-architecture modulationImproves arousability from deep sleep — believed to be the anti-enuresis mechanism in non-responders to antimuscarinics[1][4][6]
Vasopressin-independent antidiuretic effect↑ α-adrenergic stimulation of proximal renal tubule → ↑ sodium / water / urea reabsorption → ↓ nocturnal urine output[5]

The anti-enuretic effect is pharmacologically distinct from the antidepressant effect — imipramine helps children who have failed pure antimuscarinic therapy, which neither imipramine nor amitriptyline would do if its only relevant action were M-blockade.[1][4][6]

Formulations and Dosing​

FormulationStrengthsTypical urologic dosing
Imipramine HCl tablets10, 25, 50 mgEnuresis: 25–75 mg QHS (see below); adult off-label: 25–150 mg QHS[1][11]
Imipramine pamoate capsules75, 100, 125, 150 mgNot used for enuresis; adult depression-dose formulation occasionally used off-label for OAB

Enuresis (only FDA-approved urologic indication)[1]​

  • Exclude organic causes first; in patients with daytime frequency / urgency, VCUG and cystoscopy as indicated before starting.
  • Ages 6–12: start 25 mg 1 hour before bedtime; increase to 50 mg if inadequate after 1 week.
  • Ages ≥ 12: may increase to 75 mg QHS.
  • Maximum: 75 mg/day in children; do not exceed 2.5 mg/kg/day.
  • Effectiveness may decrease with continued use; relapse on discontinuation is common — taper rather than stop abruptly.

Off-label adult voiding indications​

  • OAB / detrusor overactivity: titrated up to 150 mg QHS in the seminal Castleden 1981 case series[11]; modern practice rarely exceeds 75 mg QHS given cardiac risk.
  • SUI: 75 mg/day (dose used in the Gilja 1984 open-label series)[14] — but see the Kornholt 2019 negative RCT below before prescribing.[15]
warning

Imipramine has a narrow therapeutic index and is among the most lethal medications in overdose — particularly in children. Counsel parents about secure storage; dispense limited quantities; confirm baseline ECG before initiating and after dose increases.

Indications in Reconstructive and Functional Urology​

1. Childhood nocturnal enuresis — FDA-approved​

Second- or third-line after behavioral therapy, desmopressin, enuresis alarms, and antimuscarinics have failed.[7][8]

Efficacy data:

  • Cochrane meta-analysis (Glazener & Evans): imipramine yields ~1 fewer wet night per week vs placebo (MD −0.95; 95% CI −1.40 to −0.50); 78% of children fail to achieve 14 consecutive dry nights on imipramine vs 95% on placebo (RR 0.74; 95% CI 0.61–0.90).[4]
  • Imipramine + oxybutynin outperforms placebo more convincingly (33% vs 78% failure to achieve 14 dry nights; RR 0.43) — the rational combination for mixed monosymptomatic / polysymptomatic enuresis.[4]
  • Gepertz & Nevéus 2004 (retrospective, n = 49 therapy-resistant enuretic children who had failed desmopressin, alarm, and antimuscarinic): 64.6% response rate, with 22 of 31 responders becoming completely dry.[8]
  • Favorable predictors in the Gepertz cohort: older age, low spontaneous bladder capacity.[8]
  • Poor predictors: constipation, daytime incontinence — treat these first.[8]

Baseline ECG is prudent before initiation to rule out long-QT syndrome.[7]

2. Overactive bladder / detrusor overactivity — off-label​

The dual action — ↓ detrusor contractility + ↑ outlet resistance — is theoretically attractive, but data are thin and old.

  • Castleden 1981 (n = 10 elderly patients, unstable detrusor contractions, imipramine titrated to 150 mg QHS): 6/10 became continent, mean +105 mL capacity, −18 cm H₂O bladder pressure at capacity, +30 cm H₂O urethral pressure.[11]
  • The AHCPR guidelines and subsequent Cochrane reviews have cautioned that TCAs should be reserved for carefully evaluated patients given the side-effect profile.[12][13]
  • Modern OAB pharmacotherapy — antimuscarinics, β₃-agonists (mirabegron, vibegron), onabotulinumtoxinA — has displaced imipramine from routine use.[9][10]

3. Stress urinary incontinence — off-label, low-quality evidence against​

  • Gilja 1984 (open-label, n = 30 women, 75 mg/day × 4 weeks): 71% became continent with extension of functional urethral length.[14]
  • Kornholt 2019 (double-blind, placebo-controlled, crossover RCT in 16 healthy women, single 50 mg dose): urethral opening pressure rose by only 6.5 cm H₂O at rest and 7.9 cm H₂O during squeeze — neither statistically significant nor clinically relevant.[15] Authors recommend against off-label use for SUI.
  • No RCTs exist for imipramine as SUI therapy.[3]
  • For urethral-closure-pressure augmentation, duloxetine has a better evidence base (EU-approved though not US-approved for SUI).

4. Mixed urinary incontinence — off-label, no data​

  • Recommended on mechanistic grounds (antimuscarinic for urge component, NE-reuptake for stress component), but no data exist on effectiveness in mixed UI.[3]
  • In practice, treat the dominant symptom with first-line therapy for that subtype rather than pursuing imipramine as a two-in-one.

5. Interstitial cystitis / bladder pain syndrome — other TCAs preferred​

  • For IC/BPS, amitriptyline is the TCA of choice and is the one specifically recommended in AUA and international guidelines.[16][17][18]
  • Network meta-analysis (Di 2021): amitriptyline reduced ICSI scores by MD −4.9 (95% CI −9.0 to −0.76) vs placebo.[19]
  • Imipramine is occasionally used when amitriptyline fails or is poorly tolerated, but has no dedicated IC/BPS trial data.[20][21]
  • See the TCAs hub for class-level IC/BPS detail and the ≥ 50 mg/day efficacy threshold.

Contraindications & Precautions​

Absolute / boxed-warning concerns[1]

  • Suicidality in children, adolescents, and young adults (TCA class boxed warning)
  • Concomitant MAOIs (hypertensive crisis)
  • Acute recovery phase after MI

Cardiac[1]

  • QT prolongation, arrhythmias, heart block, orthostatic hypotension, tachycardia
  • Baseline ECG required before initiation and with dose escalation, particularly in children and the elderly
  • Use with caution in structural or conduction disease

Anticholinergic (urologic relevance)[1]

  • Urinary retention — the same mechanism that helps OAB can precipitate retention in men with BOO, patients with underactive detrusor, or those on concurrent antimuscarinics
  • Narrow-angle glaucoma, xerostomia, constipation, blurred vision

Neurologic[1]

  • Lowers seizure threshold — caution in epilepsy
  • Sedation, tremor, dizziness

Endocrine / sexual[1]

  • SIADH, gynecomastia, decreased libido, ejaculatory dysfunction

Drug interactions[1]

  • CYP2D6 inhibitors (fluoxetine, paroxetine, bupropion) substantially raise imipramine levels
  • MAOIs — contraindicated
  • Other anticholinergics — cumulative burden; risk of paralytic ileus
  • Sympathomimetics and CNS depressants — potentiated
  • Alcohol — increased sedation and lowered seizure threshold

Pregnancy and lactation[1]

  • Use only if potential benefit justifies potential fetal risk; excreted in breast milk.

Perioperative Considerations​

  • Continue perioperatively for enuresis patients on a stable dose — abrupt discontinuation causes rebound nausea, headache, and malaise, and for adult patients on chronic TCA therapy may precipitate cholinergic rebound.
  • ECG review before any procedure requiring general anesthesia or agents that prolong QT (ondansetron, macrolides, fluoroquinolones, methadone).
  • Flag urinary retention risk after any pelvic, prolapse, or sling procedure — imipramine adds anticholinergic load at the same time the bladder is recovering from surgical edema and opioid analgesia.
  • Avoid concomitant anticholinergics where possible in the perioperative window; if unavoidable, monitor for post-op ileus.
  • Be wary of serotonin syndrome — combinations with linezolid, methylene blue (at intraoperative doses), tramadol, and other serotonergic agents can precipitate it. See methylene blue for the specific intraoperative caveat.

Evidence Summary​

IndicationEvidence LevelKey Trial / GuidelineNotes
Childhood nocturnal enuresisFDA-approved (1b)Cochrane[4]; Gepertz 2004[8]; AAFP 2022[7]Second/third-line after desmopressin, alarm, antimuscarinic
Imipramine + oxybutynin for refractory enuresis1bCochrane[4]RR 0.43 for failure to achieve 14 dry nights
OAB / detrusor overactivity3 (historical case series)Castleden 1981[11]Displaced by antimuscarinics, β₃-agonists, BoNT
SUINot supportedKornholt 2019 RCT[15]No clinically relevant rise in urethral closure pressure
Mixed UINo dataNorton & Brubaker 2006[3]Treat dominant symptom with first-line therapy
IC/BPSClass signal, but amitriptyline preferredDi 2021 NMA[19]; AUA 2022[18]Imipramine rarely used — see TCAs hub
Nocturnal polyuria / nocturiaMechanistic signalHunsballe 1997[5]Desmopressin is the standard — imipramine is not used for isolated nocturia in adults

Practical Pearls​

  • Imipramine is the TCA with FDA-approved enuresis indication — amitriptyline is the TCA of choice for IC/BPS. Do not substitute one for the other without a mechanistic rationale.
  • Always get a baseline ECG in children, the elderly, and anyone with cardiac risk factors before starting imipramine; repeat after dose changes.
  • Dispense small quantities — TCA overdose is among the most lethal in medicine, particularly in households with young children.
  • Anticipate decreased efficacy over time for enuresis; plan for drug holidays and eventual taper rather than indefinite use.
  • Taper — do not stop abruptly. Cholinergic rebound (nausea, headache, malaise) is common.
  • Assess daytime incontinence and constipation first in children with enuresis — these predict poor imipramine response and have their own first-line therapies.
  • Do not prescribe for SUI on imipramine alone based on the Gilja series — the Kornholt 2019 RCT is methodologically stronger and negative.
  • In mixed UI, treat the dominant symptom with first-line therapy for that subtype rather than relying on imipramine's dual mechanism.
  • Screen carefully for BOO in men and for underactive detrusor in any adult before prescribing — imipramine can precipitate retention.

References​

1. US Food and Drug Administration. Imipramine Hydrochloride — prescribing information. Updated 2023-12-15.

2. Sullivan J, Abrams P. "Pharmacological management of incontinence." Eur Urol. 1999;36(Suppl 1):89–95. doi:10.1159/000052327

3. Norton P, Brubaker L. "Urinary incontinence in women." Lancet. 2006;367(9504):57–67. doi:10.1016/S0140-6736(06)67925-7

4. Glazener CM, Evans JH. "Tricyclic and related drugs for nocturnal enuresis in children." Cochrane Database Syst Rev. 2000;(2):CD002117. doi:10.1002/14651858.CD002117

5. Hunsballe JM, Rittig S, Pedersen EB, Olesen OV, Djurhuus JC. "Single dose imipramine reduces nocturnal urine output in patients with nocturnal enuresis and nocturnal polyuria." J Urol. 1997;158(3 Pt 1):830–836. doi:10.1097/00005392-199709000-00038

6. Deshpande AV, Caldwell PH, Sureshkumar P. "Drugs for nocturnal enuresis in children (other than desmopressin and tricyclics)." Cochrane Database Syst Rev. 2012;12:CD002238. doi:10.1002/14651858.CD002238.pub2

7. Lauters RA, Garcia KW, Arnold JJ. "Enuresis in children: common questions and answers." Am Fam Physician. 2022;106(5):549–556.

8. Gepertz S, Nevéus T. "Imipramine for therapy resistant enuresis: a retrospective evaluation." J Urol. 2004;171(6 Pt 2):2607–2610. doi:10.1097/01.ju.0000110613.51078.93

9. Athanasopoulos A. "The pharmacotherapy of overactive bladder." Expert Opin Pharmacother. 2011;12(7):1003–1005. doi:10.1517/14656566.2011.554397

10. Andersson KE. "Treatment of overactive bladder: other drug mechanisms." Urology. 2000;55(5A Suppl):51–57. doi:10.1016/s0090-4295(99)00495-1

11. Castleden CM, George CF, Renwick AG, Asher MJ. "Imipramine — a possible alternative to current therapy for urinary incontinence in the elderly." J Urol. 1981;125(3):318–320. doi:10.1016/s0022-5347(17)55023-5

12. Wein AJ. "Pharmacologic options for the overactive bladder." Urology. 1998;51(2A Suppl):43–47. doi:10.1016/s0090-4295(98)90009-7

13. Roxburgh C, Cook J, Dublin N. "Anticholinergic drugs versus other medications for overactive bladder syndrome in adults." Cochrane Database Syst Rev. 2007;(4):CD003190. doi:10.1002/14651858.CD003190.pub4

14. Gilja I, Radej M, Kovacić M, Parazajder J. "Conservative treatment of female stress incontinence with imipramine." J Urol. 1984;132(5):909–911. doi:10.1016/s0022-5347(17)49941-1

15. Kornholt J, Sonne DP, Riis T, Sonne J, Klarskov N. "Effect of imipramine on urethral opening pressure: a randomized, double-blind, placebo-controlled crossover study in healthy women." Neurourol Urodyn. 2019;38(4):1076–1080. doi:10.1002/nau.23955

16. Buford K, Peters KM, Riedl C, et al. "Global consensus on interstitial cystitis/bladder pain syndrome: an update on therapeutic treatments." Neurourol Urodyn. 2025. doi:10.1002/nau.70106

17. Chermansky CJ, Guirguis MO. "Pharmacologic management of interstitial cystitis/bladder pain syndrome." Urol Clin North Am. 2022;49(2):273–282. doi:10.1016/j.ucl.2022.01.003

18. Clemens JQ, Erickson DR, Varela NP, Lai HH. "Diagnosis and treatment of interstitial cystitis/bladder pain syndrome." J Urol. 2022;208(1):34–42. doi:10.1097/JU.0000000000002756

19. Di XP, Luo DY, Jin X, et al. "Efficacy and safety comparison of pharmacotherapies for interstitial cystitis and bladder pain syndrome: a systematic review and Bayesian network meta-analysis." Int Urogynecol J. 2021;32(5):1129–1141. doi:10.1007/s00192-020-04659-w

20. French LM, Bhambore N. "Interstitial cystitis/painful bladder syndrome." Am Fam Physician. 2011;83(10):1175–1181.

21. Metts JF. "Interstitial cystitis: urgency and frequency syndrome." Am Fam Physician. 2001;64(7):1199–1206.