Clomipramine
Indications
| Indication | Approved Population | Therapy Type | Status |
|---|---|---|---|
| Obsessive-Compulsive Disorder (OCD) | ≥10 years | Monotherapy or adjunctive | FDA Approved |
Clomipramine holds a unique position among the tricyclic antidepressants as the most potent serotonin reuptake inhibitor in its class. It was the first medication approved by the FDA for OCD (1989) and remains a cornerstone of treatment for patients who do not respond adequately to SSRIs. In pivotal trials, clomipramine produced a 35–42% reduction in Yale-Brown Obsessive Compulsive Scale (Y-BOCS) scores in adults and 37% in children and adolescents, significantly outperforming placebo. Despite its robust efficacy, it is generally reserved as a second-line agent due to its side-effect burden compared with SSRIs.
Major depressive disorder — Clomipramine is approved for depression in many countries outside the US. Some meta-analyses suggest it may have superior efficacy to other antidepressants in severe MDD, though evidence is not conclusive. (Evidence quality: Moderate)
Panic disorder — Used at 25–150 mg/day; evidence from multiple RCTs. (Evidence quality: Moderate)
Premature ejaculation — Low-dose (25–50 mg) on-demand or daily use; well-established off-label application. (Evidence quality: Moderate)
Cataplexy (narcolepsy) — Used for anticataplectic effect via serotonergic/noradrenergic mechanisms. (Evidence quality: Low)
Body dysmorphic disorder / Trichotillomania — Related to OCD spectrum; some supporting evidence. (Evidence quality: Low)
Chronic pain syndromes — Neuropathic pain at 25–150 mg/day. (Evidence quality: Low)
Dosing
Adult Dosing by Clinical Scenario
| Clinical Scenario | Starting Dose | Maintenance Dose | Maximum Dose | Notes |
|---|---|---|---|---|
| OCD — initial treatment | 25 mg/day | 100–250 mg/day | 250 mg/day | Increase by 25 mg every 4–7 days; max 100 mg in first 2 weeks; divide with meals during titration, then consolidate QHS Onset of anti-OCD effect typically 6–12 weeks |
| OCD — SSRI augmentation | 25 mg QHS | 75–150 mg/day | 250 mg/day | Commonly combined with an SSRI; monitor CMI levels due to CYP2D6 inhibition by SSRIs Combined CMI + DCMI target: 150–300 ng/mL |
| Depression (off-label) | 25 mg QHS | 100–150 mg/day | 250 mg/day | Titrate over 2–4 weeks; bedtime dosing preferred for sedation Not FDA-approved for depression in the US |
| Premature ejaculation (off-label) | 25 mg | 25–50 mg daily or on-demand (4–6 h before intercourse) | 50 mg/day | Low doses exploit serotonergic-mediated ejaculation delay On-demand use reduces overall side-effect exposure |
| Chronic neuropathic pain (off-label) | 10–25 mg QHS | 75–150 mg/day | 150 mg/day | Used similarly to amitriptyline; bedtime dosing preferred Analgesic effect may precede full antidepressant response |
Paediatric & Special Population Adjustments
| Population | Starting Dose | Maintenance Dose | Maximum Dose | Notes |
|---|---|---|---|---|
| Children & adolescents (10–17 y) — OCD | 25 mg/day | Up to 3 mg/kg/day or 100 mg (lower value) | 3 mg/kg/day or 200 mg (lower value) | Max 100 mg in first 2 weeks; divide with meals during titration FDA-approved for OCD in ≥10 years only |
| Elderly (≥65 years) | 10–25 mg QHS | Titrate cautiously | Individualize (lower doses) | Higher sensitivity to anticholinergic and cardiovascular effects Lower steady-state concentrations occur in younger adults vs elderly |
| Hepatic impairment | Low dose | Titrate cautiously | Individualize | Effects of hepatic impairment on disposition not formally studied Monitor LFTs periodically; SGOT/SGPT elevations reported in 1–3% |
| CYP2D6 poor metabolisers | Reduce dose | Guided by plasma levels | Individualize | Higher CMI accumulation; consider pharmacogenomic testing TDM target: combined CMI + DCMI 150–300 ng/mL |
Clomipramine and its active metabolite desmethylclomipramine exhibit capacity-limited (saturable) metabolism. Above 150 mg/day, plasma levels may rise disproportionately, prolonging half-lives and increasing seizure risk. Therapeutic drug monitoring is strongly recommended when doses exceed 150 mg/day or when CYP2D6 inhibitors are co-prescribed. Steady state takes 2–3 weeks at a given dose.
Clomipramine Pharmacology
Mechanism of Action
Clomipramine is the most serotonin-selective of the tricyclic antidepressants. The parent compound potently inhibits the serotonin transporter (SERT), which is believed to underlie its anti-obsessional efficacy. Its principal metabolite, desmethylclomipramine (DCMI), preferentially inhibits norepinephrine reuptake, adding dual-action antidepressant properties but also increasing anticholinergic and cardiovascular side effects. Additionally, clomipramine blocks histamine H1 receptors (contributing to sedation and weight gain), muscarinic acetylcholine receptors (responsible for anticholinergic effects), and alpha-1 adrenergic receptors (causing orthostatic hypotension). Like other TCAs, it also blocks cardiac sodium channels, which creates a narrow therapeutic-toxic window in overdose. The serotonergic selectivity of the parent compound is what distinguishes clomipramine from other TCAs in OCD treatment.
ADME Profile
| Parameter | Value | Clinical Implication |
|---|---|---|
| Absorption | Well absorbed; bioavailability ~50%; Tmax 2–6 h (mean 4.7 h); food does not significantly affect absorption | Can be taken with or without food; divided dosing with meals during titration reduces GI side effects |
| Distribution | Extensive distribution into brain and CSF; protein binding ~97% (albumin); DMI CSF/plasma ratio 2.6 | High protein binding means potential displacement interactions with other highly bound drugs; CNS penetration supports central efficacy |
| Metabolism | Hepatic: CYP2D6 and CYP3A4 (demethylation to DCMI); CYP1A2, CYP2C19 also involved; DCMI is pharmacologically active (t½ ~69 h) | Nonlinear pharmacokinetics above 150 mg/day; CYP2D6 PMs accumulate drug; smoking induces CYP1A2 and lowers CMI levels |
| Elimination | t½ CMI: 19–37 h (mean 32 h); t½ DCMI: 54–77 h (mean 69 h); 60% urine, 32% faeces; <1% unchanged in urine | Long metabolite half-life means steady state takes 2–3 weeks; dose changes should be separated by at least 2 weeks |
Side Effects
Clomipramine has a high side-effect burden compared with SSRIs. The incidence data below are from placebo-controlled OCD trials (adults N=322, placebo N=319) from the Anafranil PI.
| Adverse Effect | Incidence (CMI) | Placebo | Clinical Note |
|---|---|---|---|
| Dry mouth | 84% | 17% | Anticholinergic; encourage oral hygiene, sugar-free gum |
| Somnolence | 54% | 16% | Dose-related; consolidate dose at bedtime once tolerated |
| Tremor | 54% | 2% | Fine postural tremor; may respond to dose reduction or propranolol |
| Dizziness | 54% | 14% | Orthostatic component; advise slow position changes |
| Headache | 52% | 41% | High placebo rate suggests only partly drug-attributable; treat symptomatically |
| Constipation | 47% | 11% | Anticholinergic; increase fibre and fluids |
| Ejaculation failure (males) | 42% | 2% | Serotonergic effect; therapeutic for premature ejaculation but distressing for others |
| Fatigue | 39% | 18% | Often improves over weeks; bedtime dosing helps |
| Nausea | 33% | 14% | Serotonergic; take with food; usually attenuates over 2 weeks |
| Increased sweating | 29% | 3% | Noradrenergic/serotonergic; may persist long-term |
| Insomnia | 25% | 15% | Paradoxical; consider dose timing adjustment |
| Dyspepsia | 22% | 10% | Take with meals during titration phase |
| Libido change | 21% | 3% | Serotonergic; significant impact on adherence |
| Impotence (males) | 20% | 3% | May require dose reduction or switching |
| Weight gain | 18% | 1% | Antihistaminic effect; monitor weight regularly |
| Abnormal vision | 18% | 4% | Anticholinergic mydriasis; rule out angle closure if eye pain |
| Nervousness | 18% | 2% | Serotonergic activation; usually transient |
| Micturition disorder | 14% | 2% | Anticholinergic urinary hesitancy; caution in BPH |
| Myoclonus | 13% | <1% | Serotonergic; nocturnal jerks common; assess for serotonin syndrome at high doses |
| Anorexia | 12% | <1% | May coexist with weight gain (appetite vs metabolic effects diverge) |
| Increased appetite | 11% | 2% | Antihistaminic; dietary counselling recommended |
| Adverse Effect | Incidence | Clinical Note |
|---|---|---|
| Paresthesia | 9% | Peripheral neuropathic sensation; usually benign |
| Memory impairment | 9% | Anticholinergic cognitive burden; problematic in elderly |
| Taste perversion | 8% | Metallic taste; usually transient |
| Rash | 8% | Assess for DRESS if systemic symptoms present |
| Flushing | 8% | Vasomotor instability |
| Vomiting | 7% | Serotonergic; take with food |
| Tinnitus | 6% | Monitor; may indicate ototoxicity at high levels |
| Postural hypotension | 6% | Alpha-1 blockade; falls risk in elderly |
| Tachycardia | 4% | Anticholinergic; obtain ECG if symptomatic |
| Palpitations | 4% | Usually benign; ECG if persistent |
| Adverse Effect | Estimated Frequency | Typical Onset | Required Action |
|---|---|---|---|
| Seizures | ~1.5% cumulative at 1 year | Dose- and duration-dependent | Limit dose to ≤250 mg/day; discontinue if seizure occurs; avoid in patients with seizure history |
| Suicidal ideation / behaviour | Uncommon (age-dependent) | First weeks to months | Close monitoring especially <25 years; consider stopping if emergent suicidality |
| Serotonin syndrome | Rare | Hours to days after adding serotonergic drug | Discontinue all serotonergic agents; supportive care; cyproheptadine |
| Cardiac arrhythmia / QRS prolongation | ECG abnormalities in 1.5% | Any time; higher risk in overdose | Baseline ECG; monitor QRS; discontinue if >120 ms; cardiology consult |
| DRESS (Drug Rash with Eosinophilia & Systemic Symptoms) | Rare (postmarketing) | 2–8 weeks | Discontinue immediately; dermatology/allergy consult |
| Hepatotoxicity | SGOT ≥3×ULN in ~1%; SGPT ≥3×ULN in ~3% | Weeks to months | Monitor LFTs; discontinue if significant elevation or jaundice |
| Mania / hypomania | Uncommon | First weeks | Discontinue; screen for bipolar disorder; initiate mood stabiliser |
| Hyponatraemia (SIADH) | Rare | Weeks | Check sodium; elderly at higher risk; fluid restriction |
| Reason for Discontinuation | Incidence | Context |
|---|---|---|
| Somnolence / sedation | Primary CNS reason (5.4% total CNS) | Most common identifiable cause; bedtime dosing may mitigate |
| Nausea / vomiting | Primary GI reason (1.3% total GI) | Usually improves with food and gradual titration |
| Sexual dysfunction | Significant contributor | Ejaculatory failure and libido change commonly cited; dose-related |
Sexual side effects occur in 30–40% of patients and are one of the leading causes of non-adherence. Strategies include dose reduction to the minimum effective dose, timing the dose after sexual activity, or adding a PDE-5 inhibitor for erectile dysfunction. For ejaculatory delay that is therapeutically desired (premature ejaculation), the same mechanism becomes the indication rather than the side effect.
Drug Interactions
Clomipramine is metabolised primarily by CYP2D6 (to DCMI) and CYP3A4, with contributions from CYP1A2 and CYP2C19. It does not induce drug-metabolising enzymes. Its very high protein binding (~97%) creates a theoretical risk of displacement interactions.
Monitoring
-
ECG
Baseline; repeat at therapeutic dose and if dose >150 mg/day
Routine Assess QRS, QTc, and conduction intervals. ECG abnormalities developed in 1.5% of patients in premarketing trials. QRS >100 ms warrants caution; >120 ms requires dose reduction or discontinuation. -
TDM (Plasma Levels)
After 3–4 weeks on stable dose; and with any dose change
Routine Measure trough combined CMI + DCMI levels. Target range 150–300 ng/mL. Mandatory when dose >150 mg/day, when co-prescribed with CYP2D6/1A2 inhibitors, or if toxicity suspected. Nonlinear kinetics make TDM essential. -
Blood Pressure
Baseline; during titration
Routine Orthostatic hypotension in ~20% of patients (often asymptomatic). Lying and standing measurements recommended, especially in elderly. -
Liver Function
Baseline; periodically during treatment
Routine Transaminase elevations (SGOT ~1%, SGPT ~3% ≥3×ULN) reported in premarketing trials. Rare postmarketing reports of severe hepatic injury. Discontinue if jaundice or significant elevation. -
Weight & BMI
Baseline, then every 3 months
Routine Weight gain in 18% of patients. Early dietary and exercise counselling recommended. -
Mental State
Every visit for first 3 months
Routine Monitor for suicidality (especially <25 years), manic switching, and psychosis activation. Y-BOCS scores to track OCD response. -
Sodium
If confusion, nausea, headache in elderly
Trigger-Based SIADH-related hyponatraemia reported; elderly at greater risk.
Contraindications & Cautions
Absolute Contraindications
- Hypersensitivity to clomipramine or other tricyclic antidepressants (cross-reactivity within dibenzazepine class)
- Concurrent MAOI use or use within 14 days of stopping an MAOI (including linezolid and IV methylene blue)
- Acute recovery period after myocardial infarction
Relative Contraindications (Specialist Input Recommended)
- Severe cardiovascular disease — conduction abnormalities, heart failure, recent arrhythmias; TCA cardiotoxicity risk
- Seizure disorder or history of seizures — clomipramine lowers seizure threshold dose-dependently; cumulative seizure rate ~1.5% at 1 year
- Untreated narrow-angle glaucoma — anticholinergic mydriasis may trigger angle closure
- Severe hepatic impairment — extensive hepatic metabolism; rare fatal hepatotoxicity reported postmarketing
- Bipolar disorder (unscreened) — risk of manic switching; screen before initiation
Use with Caution
- Urinary retention / prostatic hypertrophy — anticholinergic effects worsen obstructive symptoms
- Elderly patients — higher sensitivity to anticholinergic, cardiovascular, and sedative effects; hyponatraemia risk
- Patients at risk of suicide — prescribe smallest feasible quantity; TCA overdose has a narrow toxic-to-therapeutic ratio
- CYP2D6 poor metabolisers — increased exposure; TDM advised
- Smokers — smoking induces CYP1A2; smoking cessation may raise clomipramine levels significantly
Antidepressants, including clomipramine, increase the risk of suicidal thinking and behaviour in children, adolescents, and young adults (<25 years) in short-term studies. In pooled analyses of over 4,400 paediatric and 77,000 adult patients, the risk was 14 additional cases per 1,000 treated in those under 18 and 5 additional per 1,000 in those aged 18–24. All patients should be monitored for clinical worsening and emergence of suicidal thoughts, especially during the initial months of therapy and at dose changes. Clomipramine is not approved for paediatric use except for OCD in patients ≥10 years.
Patient Counselling
Purpose of Therapy
Clomipramine works by adjusting the balance of serotonin in the brain, which helps reduce obsessive thoughts and compulsive behaviours. It typically takes 6 to 12 weeks for the full anti-OCD effect to become apparent. Patients should understand that improvement is gradual and should not stop the medication abruptly even if they feel it is not working in the first few weeks.
How to Take
During the first weeks, clomipramine should be taken in divided doses with meals to reduce nausea. Once a stable dose is reached, the full daily dose can be taken at bedtime to take advantage of its sedating effects and reduce daytime drowsiness. Capsules can be opened and mixed with soft food for patients who have difficulty swallowing.
Sources
- Anafranil (clomipramine hydrochloride) Capsules USP — Full Prescribing Information. SpecGx LLC (Mallinckrodt). Revised September 2024. DailyMed Primary source for FDA-approved indication, dosing, pharmacokinetics, adverse reactions, contraindications, and drug interactions.
- Clomipramine Collaborative Study Group. Clomipramine in the treatment of patients with obsessive-compulsive disorder. Arch Gen Psychiatry. 1991;48(8):730–738. DOI Landmark multicenter placebo-controlled trial establishing clomipramine efficacy in OCD in adults.
- DeVeaugh-Geiss J, Moroz G, Biederman J, et al. Clomipramine hydrochloride in childhood and adolescent obsessive-compulsive disorder — a multicenter trial. J Am Acad Child Adolesc Psychiatry. 1992;31(1):45–49. DOI Pivotal paediatric OCD trial supporting FDA approval for ages 10–17.
- Ackerman DL, Greenland S. Multivariate meta-analysis of controlled drug studies for obsessive-compulsive disorder. J Clin Psychopharmacol. 2002;22(3):309–317. DOI Meta-analysis comparing clomipramine with SSRIs in OCD, showing clomipramine retains a significant efficacy advantage.
- Soomro GM, Altman DG, Rajagopal S, Oakley Browne M. Selective serotonin re-uptake inhibitors (SSRIs) versus placebo for obsessive compulsive disorder (OCD). Cochrane Database Syst Rev. 2008;(1):CD001765. DOI Cochrane review of SSRIs in OCD, providing context for clomipramine’s place relative to SSRI monotherapy.
- American Psychiatric Association. Practice guideline for the treatment of patients with obsessive-compulsive disorder. Am J Psychiatry. 2007;164(7 Suppl):5–53. DOI APA guideline recommending clomipramine as a second-line pharmacological option after SSRI failure in OCD.
- National Institute for Health and Care Excellence (NICE). Obsessive-compulsive disorder and body dysmorphic disorder: treatment. Clinical guideline CG31 (updated 2005). NICE UK guideline positioning clomipramine as an alternative to SSRIs when response is inadequate.
- Gillman PK. Tricyclic antidepressant pharmacology and therapeutic drug interactions updated. Br J Pharmacol. 2007;151(6):737–748. DOI Comprehensive review of TCA receptor pharmacology including clomipramine’s serotonin transporter selectivity.
- Hyttel J. Pharmacological characterization of selective serotonin reuptake inhibitors (SSRIs). Int Clin Psychopharmacol. 1994;9(Suppl 1):19–26. DOI Provides comparative in-vitro serotonin transporter binding data for clomipramine versus SSRIs.
- Hiemke C, Bergemann N, Clement HW, et al. Consensus guidelines for therapeutic drug monitoring in neuropsychopharmacology: update 2017. Pharmacopsychiatry. 2018;51(1–02):9–62. DOI AGNP consensus establishing therapeutic reference range for combined CMI + DCMI (150–300 ng/mL) and TDM recommendations.
- Gex-Fabry M, Eap CB, Oneda B, et al. CYP2D6 and CYP2C19 genetic polymorphisms and steady-state plasma concentrations of clomipramine and its metabolites. Ther Drug Monit. 2008;30(5):559–569. DOI Pharmacogenomic study demonstrating the impact of CYP2D6 and CYP2C19 polymorphisms on clomipramine plasma levels.
- Vandel S, Bertschy G, Baumann P, et al. Fluvoxamine and fluoxetine: interaction studies with amitriptyline, clomipramine and neuroleptics in phenotyped patients. Pharmacol Res. 1995;31(6):347–353. DOI Documents the pharmacokinetic interaction between SSRIs and clomipramine via CYP inhibition in phenotyped patients.
- Patel P, Abdijadid S. Clomipramine. In: StatPearls [Internet]. Treasure Island, FL: StatPearls Publishing; updated August 16, 2024. NCBI Bookshelf Peer-reviewed clinical summary covering indications, dosing, PK, adverse effects, and interprofessional management.