Nortriptyline
Pamelor, Aventyl
Indications
| Indication | Approved Population | Therapy Type | Status |
|---|---|---|---|
| Depression | Adults | Monotherapy or adjunctive | FDA Approved |
Nortriptyline is the active metabolite of amitriptyline and is classified as a secondary amine tricyclic antidepressant. It is FDA-approved solely for the relief of depressive symptoms in adults, with endogenous depression historically shown to respond more reliably than other depressive subtypes. Unlike newer antidepressants, nortriptyline carries a well-established therapeutic window of 50–150 ng/mL, which can guide dose optimisation through therapeutic drug monitoring. It is not approved for use in children or adolescents.
Neuropathic pain (diabetic neuropathy, postherpetic neuralgia, chronic pain syndromes) — Evidence quality: Moderate. Supported by multiple RCTs and guideline recommendations (AAN, NICE). Often preferred over amitriptyline due to a more favourable side-effect profile.
Migraine prophylaxis — Evidence quality: Moderate. Recommended in several headache guidelines as an alternative to amitriptyline when anticholinergic effects limit tolerability.
Smoking cessation — Evidence quality: Moderate. Cochrane reviews support nortriptyline as a second-line aid for tobacco cessation, roughly doubling quit rates compared with placebo.
Irritable bowel syndrome (IBS) — Evidence quality: Low. Some evidence for benefit in diarrhoea-predominant IBS via anticholinergic and neuromodulatory effects.
ADHD (adults) — Evidence quality: Low. Used when stimulants are contraindicated; limited trial data.
Dosing
Adult Dosing by Clinical Scenario
| Clinical Scenario | Starting Dose | Maintenance Dose | Maximum Dose | Notes |
|---|---|---|---|---|
| Major depression — outpatient initiation | 25 mg once daily at bedtime | 75–100 mg/day | 150 mg/day | Increase by 25 mg every 3–7 days as tolerated Can be given as single bedtime dose or divided TID-QID |
| Major depression — inpatient / treatment-resistant | 25 mg TID | 75–150 mg/day | 150 mg/day | Monitor plasma levels when dose exceeds 100 mg/day Target therapeutic level: 50–150 ng/mL |
| Neuropathic pain — initial management (off-label) | 10–25 mg once daily at bedtime | 25–75 mg/day | 150 mg/day | Titrate every 3–7 days by 10–25 mg increments Consider combination with gabapentin if inadequate response |
| Migraine prophylaxis (off-label) | 10–25 mg at bedtime | 25–75 mg/day | 150 mg/day | Allow 4–6 weeks for full prophylactic effect Lower doses often effective compared with depression dosing |
| Smoking cessation (off-label) | 25 mg/day | 75–100 mg/day | 100 mg/day | Start 10–28 days before quit date; continue for up to 12 weeks Titrate to maintenance over 10 days to 5 weeks |
Special Population Adjustments
| Clinical Scenario | Starting Dose | Maintenance Dose | Maximum Dose | Notes |
|---|---|---|---|---|
| Elderly patients (≥65 years) | 10–25 mg at bedtime | 30–50 mg/day | 75 mg/day | Increased sensitivity to anticholinergic and cardiovascular effects FDA PI recommends lower doses; monitor plasma levels |
| CYP2D6 poor metabolisers | 10 mg at bedtime | Guided by TDM | Guided by TDM | Consider 50% dose reduction; CPIC recommends alternative or TDM 3–10% of Caucasians are poor metabolisers |
| Hepatic impairment | 10 mg at bedtime | Individualised | Individualised | Extensively hepatically metabolised; anticipate reduced clearance No specific guidance in PI; clinical judgment required |
Nortriptyline is one of the few antidepressants with a well-validated therapeutic window (50–150 ng/mL). Plasma levels above 150 ng/mL are associated with loss of antidepressant efficacy (the “therapeutic window” phenomenon) as well as increased toxicity risk. Draw trough levels 12–16 hours post-dose at steady state (approximately 5–7 days after a stable dose). TDM is recommended whenever the daily dose exceeds 100 mg, in poor responders, in the elderly, and when CYP2D6 inhibitors are co-prescribed.
Pharmacology
Mechanism of Action
Nortriptyline is a secondary amine tricyclic antidepressant and the principal active metabolite of amitriptyline. Its antidepressant action is attributed primarily to potent inhibition of norepinephrine reuptake at the presynaptic neuronal membrane, with moderate serotonin reuptake inhibition. Downstream adaptive changes, including beta-adrenergic receptor downregulation and serotonin receptor modulation, are thought to contribute to the 2–4 week latency to clinical effect. Nortriptyline also blocks muscarinic acetylcholine receptors (producing anticholinergic effects), histamine H1 receptors (contributing to sedation and weight gain), and alpha-1 adrenergic receptors (causing orthostatic hypotension). Compared with the parent compound amitriptyline, nortriptyline is more norepinephrine-selective and has a somewhat lower anticholinergic and sedative burden, which contributes to its comparatively better tolerability profile among the tricyclics.
ADME Profile
| Parameter | Value | Clinical Implication |
|---|---|---|
| Absorption | Oral bioavailability ~51%; Tmax ~5.5 h (range 4–9 h) | Significant first-pass metabolism; food does not meaningfully alter absorption |
| Distribution | Vd 21–31 L/kg; protein binding ~93%; distributes to brain, heart, liver | Extensive tissue distribution; crosses placenta; present in breast milk at concentrations similar to maternal serum |
| Metabolism | Hepatic via CYP2D6 (primary), CYP1A2, CYP3A4, CYP2C19; active metabolite 10-hydroxynortriptyline | Subject to CYP2D6 genetic polymorphism; poor metabolisers (3–10%) may have 2–3 fold higher plasma levels; cimetidine and quinidine markedly inhibit metabolism |
| Elimination | t½ 16–90 h (mean ~30 h); ~33% excreted in urine as metabolites within 24 h; small fraction via biliary/faecal route | Long half-life permits once-daily dosing; steady state reached in 5–7 days; renal impairment does not significantly alter parent drug clearance but may affect metabolite accumulation |
Side Effects
Nortriptyline was approved before modern adverse-event reporting standards; consequently, the FDA label lists most side effects without precise incidence figures. The frequencies below are derived from pooled clinical trial data, post-marketing surveillance, and comparative studies with placebo-controlled designs where available. Nortriptyline is generally better tolerated than tertiary amine TCAs such as amitriptyline.
| Adverse Effect | Incidence | Clinical Note |
|---|---|---|
| Dry mouth (xerostomia) | 30–40% | Most frequently reported TCA effect; persists throughout treatment; increases dental caries risk long-term |
| Drowsiness / sedation | 15–25% | Less sedating than amitriptyline; usually improves within 1–2 weeks; bedtime dosing minimises daytime impact |
| Constipation | 15–20% | Anticholinergic-mediated; manage with dietary fibre and adequate hydration; rarely progresses to ileus |
| Dizziness | 10–15% | Often postural; related to alpha-1 blockade; caution in elderly with fall risk |
| Weight gain | 10–15% | H1 receptor antagonism and appetite stimulation; typically 1–3 kg over first 3–6 months |
| Adverse Effect | Incidence | Clinical Note |
|---|---|---|
| Blurred vision | 5–10% | Anticholinergic effect on ciliary muscle; usually transient; exclude narrow-angle glaucoma before prescribing |
| Tachycardia | 5–10% | Anticholinergic-mediated resting heart rate increase of 10–20 bpm is common; persistent across treatment duration |
| Urinary retention / hesitancy | 3–8% | More prominent in men and patients with prostatic hypertrophy; can progress to acute retention |
| Orthostatic hypotension | 3–7% | Alpha-1 blockade; less pronounced than with tertiary amine TCAs; measure standing BP at follow-up |
| Tremor | 3–6% | Fine postural tremor; dose-related; may indicate supratherapeutic levels |
| Nausea | 2–5% | Usually mild and self-limiting; take with food if persistent |
| Sexual dysfunction | 2–5% | Decreased libido, erectile dysfunction, delayed orgasm; less frequent than with SSRIs |
| Diaphoresis | 2–5% | Noradrenergic-mediated; can be bothersome; persists in some patients |
| Adverse Effect | Estimated Frequency | Typical Onset | Required Action |
|---|---|---|---|
| Suicidal ideation / behaviour | Uncommon | First 1–2 months or dose change | FDA Boxed Warning; close monitoring in those <25 years; consider discontinuation if new suicidal thoughts emerge |
| Cardiac arrhythmia / QRS prolongation | Rare (~0.1–1%) | Any time; risk increases with overdose | Baseline and follow-up ECG; discontinue if QRS >120 ms or new conduction abnormality; lethal in overdose |
| Seizures | Rare (~0.1–0.4%) | Dose-dependent; more common at >150 mg/day | Avoid in patients with uncontrolled epilepsy; discontinue and manage seizure acutely |
| Serotonin syndrome | Rare | Hours to days after adding serotonergic agent | Discontinue all serotonergic agents immediately; supportive care; cyproheptadine if severe |
| Paralytic ileus | Very rare | Any time; increased risk in elderly or with concomitant anticholinergics | Surgical emergency; discontinue nortriptyline; assess for other anticholinergic contributors |
| Hepatotoxicity (cholestatic jaundice) | Very rare | Weeks to months | Monitor LFTs if symptoms arise; discontinue if jaundice or significant transaminase elevation |
| Agranulocytosis / bone marrow suppression | Very rare | Weeks to months | CBC if unexplained fever, sore throat, or infection; discontinue and refer if confirmed |
| Mania / hypomania induction | Uncommon | First 2–8 weeks | Screen for bipolar disorder before starting; discontinue nortriptyline and manage manic episode |
| Reason for Discontinuation | Incidence | Context |
|---|---|---|
| Anticholinergic effects | 5–8% | Dry mouth and constipation most often cited; worse in elderly |
| Excessive sedation | 3–5% | More common at doses >75 mg/day; bedtime dosing may help |
| Weight gain | 2–4% | Becomes a reason for discontinuation particularly after 3–6 months |
| Cardiovascular effects | 1–3% | Tachycardia, orthostatic hypotension, palpitations |
Anticholinergic effects are the most common reason for nortriptyline discontinuation. Sugar-free gum and adequate hydration help with dry mouth. Dietary fibre and stool softeners address constipation before it becomes severe. If anticholinergic burden is intolerable, consider switching to an antidepressant with lower muscarinic activity. Avoid combining nortriptyline with other anticholinergic medications, especially in elderly patients where cumulative anticholinergic burden raises the risk of delirium, cognitive impairment, and falls.
Drug Interactions
Nortriptyline is primarily metabolised by CYP2D6, with minor contributions from CYP1A2, CYP3A4, and CYP2C19. Its pharmacology also creates interaction risks through anticholinergic, adrenergic, and serotonergic mechanisms. Clinically significant interactions include the following:
Monitoring
-
ECG
Baseline; repeat if dose >100 mg/day or cardiac symptoms
Routine Assess QRS duration, QTc interval, and PR interval before initiation, particularly in patients ≥65 years, those with cardiac risk factors, or with co-prescribed QT-prolonging drugs. QRS >100 ms is a warning; >120 ms warrants discontinuation or specialist cardiology input. -
Plasma Drug Level
At steady state when dose >100 mg/day; repeat with dose changes
Routine Draw trough level 12–16 h post-dose after at least 5–7 days at a stable dose. Therapeutic window: 50–150 ng/mL. Levels >150 ng/mL are associated with reduced efficacy and increased toxicity. Also recommended in poor responders, the elderly, CYP2D6 polymorphism suspects, and when CYP2D6 inhibitors are co-prescribed. -
Blood Pressure
Each visit during titration; then periodically
Routine Orthostatic vital signs (lying and standing) at baseline and during titration. Alpha-1 blockade can cause symptomatic postural hypotension, particularly in the elderly. -
Psychiatric Status
Weekly for first 4 weeks; then every 2–4 weeks
Routine Assess for clinical worsening, suicidality, agitation, and emergence of mania/hypomania. FDA mandates close monitoring especially in patients <25 years and during initial treatment or dose changes. -
Weight & Metabolic
Baseline, then every 3–6 months
Routine Record weight and BMI. Nortriptyline can cause weight gain and may alter glucose metabolism. Monitor fasting glucose in patients with diabetes or pre-diabetes. -
Hepatic Function
If symptoms develop
Trigger-based Check LFTs if patient develops jaundice, dark urine, malaise, or unexplained right upper quadrant discomfort. Rare cases of cholestatic hepatotoxicity reported with TCAs. -
Intraocular Pressure
If eye symptoms develop
Trigger-based Screen for narrow-angle glaucoma before prescribing. Anticholinergic mydriasis can precipitate acute angle-closure. Refer urgently if eye pain, halos, or acute visual loss occur.
Contraindications & Cautions
Absolute Contraindications
- Concurrent or recent MAOI use — at least 14 days must elapse between discontinuation of an MAOI and initiation of nortriptyline, and vice versa. This includes linezolid and intravenous methylene blue.
- Acute recovery phase after myocardial infarction — risk of cardiac arrhythmias and conduction disturbances is markedly elevated.
- Known hypersensitivity to nortriptyline or other dibenzazepine compounds (cross-sensitivity possible with amitriptyline, imipramine).
Relative Contraindications (Specialist Input Recommended)
- Pre-existing cardiac conduction disease (bundle branch block, prolonged QTc) — requires cardiology consultation and ECG monitoring if benefit clearly outweighs risk.
- Uncontrolled narrow-angle glaucoma — anticholinergic effects may precipitate angle closure.
- Severe hepatic impairment — extensively metabolised; reduced clearance increases toxicity risk.
- Known CYP2D6 poor metaboliser status without access to therapeutic drug monitoring.
- Active suicidal ideation in patients <25 years — FDA Boxed Warning; requires risk–benefit analysis and intensive monitoring plan.
Use with Caution
- History of seizure disorder — nortriptyline lowers the seizure threshold in a dose-dependent manner.
- Urinary retention / prostatic hypertrophy — anticholinergic effects may worsen obstruction.
- Elderly patients — increased sensitivity to anticholinergic, cardiovascular, and CNS effects; Beers Criteria lists TCAs as potentially inappropriate in older adults.
- Bipolar disorder — may precipitate manic episode; not approved for bipolar depression; screen before initiating.
- Hyperthyroidism — enhanced cardiovascular effects of TCAs.
- Diabetes mellitus — may alter glucose control; case reports of significant hypoglycaemia with concurrent sulfonylureas.
- Patients undergoing surgery — inform anaesthetist; nortriptyline potentiates catecholamines and may interact with anaesthetic agents.
Antidepressants increase the risk of suicidal thinking and behaviour in children, adolescents, and young adults (18–24 years) with major depressive disorder and other psychiatric disorders. Nortriptyline is not approved for use in paediatric patients. All patients started on antidepressant therapy must be monitored closely for clinical worsening, suicidality, or unusual behavioural changes, particularly during the first months of therapy or at times of dose adjustments. Families and caregivers should be advised of the need for daily observation and immediate reporting of emergent symptoms.
Patient Counselling
Purpose of Therapy
Nortriptyline is prescribed to help restore the balance of certain brain chemicals involved in mood regulation. It may take 2 to 4 weeks before the full antidepressant benefit becomes apparent, and it is important to continue taking the medication as directed even if improvement is not immediately noticeable. For pain conditions, nortriptyline works at lower doses by modifying the way nerves transmit pain signals.
How to Take
Nortriptyline can be taken with or without food. It is most commonly taken once daily at bedtime because of its sedating properties, although some patients may be directed to take it in divided doses. Swallow capsules whole with a glass of water. The oral solution should be measured carefully with the provided measuring device. Do not stop nortriptyline abruptly; a gradual taper over 10–14 days is recommended to avoid withdrawal symptoms such as nausea, headache, and irritability.
Sources
- Mallinckrodt Inc. Pamelor (nortriptyline HCl) capsules USP — Full Prescribing Information. Hazelwood, MO; 2012. FDA Label (PDF) Primary US prescribing reference for indications, dosing, contraindications, and boxed warning text.
- Teva Pharmaceuticals. Nortriptyline Hydrochloride Capsules USP — Prescribing Information. Rev. K 9/2025. Drugs.com PI Current generic label with updated adverse reaction reporting and boxed warning language.
- Medsafe New Zealand. Nortriptyline NRIM Data Sheet. 2013. Medsafe (PDF) Contains detailed pharmacokinetic parameters including bioavailability (51%), Vd, Tmax, and protein binding data.
- Kragh-Sørensen P, Hansen CE, Baastrup PC, Hvidberg EF. Self-inhibiting action of nortriptyline’s antidepressive effect at high plasma levels. Psychopharmacologia. 1976;45(3):305–312. DOI Landmark study establishing the therapeutic window concept for nortriptyline (50–150 ng/mL).
- Hughes JR, Stead LF, Hartmann-Boyce J, Cahill K, Lancaster T. Antidepressants for smoking cessation. Cochrane Database Syst Rev. 2014;(1):CD000031. DOI Cochrane review demonstrating nortriptyline approximately doubles long-term quit rates vs placebo.
- Gilron I, Bailey JM, Tu D, Holden RR, Jackson AC, Houlden RL. Nortriptyline and gabapentin, alone and in combination for neuropathic pain: a double-blind, randomised controlled crossover trial. Lancet. 2009;374(9697):1252–1261. DOI Demonstrated superior analgesia with nortriptyline-gabapentin combination vs either drug alone in neuropathic pain.
- Hicks JK, Sangkuhl K, Swen JJ, et al. Clinical Pharmacogenetics Implementation Consortium (CPIC) Guideline for CYP2D6 and CYP2C19 Genotypes and Dosing of Tricyclic Antidepressants: 2016 Update. Clin Pharmacol Ther. 2017;102(1):37–44. DOI CPIC guideline recommending dose adjustments for CYP2D6 poor and ultrarapid metabolisers of TCAs including nortriptyline.
- Finnerup NB, Attal N, Haroutounian S, et al. Pharmacotherapy for neuropathic pain in adults: a systematic review and meta-analysis. Lancet Neurol. 2015;14(2):162–173. DOI NeuPSIG systematic review recommending TCAs as first-line for neuropathic pain alongside SNRIs and gabapentinoids.
- American Psychiatric Association. Practice Guideline for the Treatment of Patients with Major Depressive Disorder, Third Edition. Am J Psychiatry. 2010;167(Suppl):1–152. DOI APA guideline positioning TCAs as second-line agents for MDD when SSRIs/SNRIs fail; recommends nortriptyline starting dose of 25 mg.
- Merwar G, Gibbons JR, Hosseini SA, Saadabadi A. Nortriptyline. In: StatPearls. Treasure Island (FL): StatPearls Publishing; Updated June 5, 2023. NCBI Comprehensive clinical review covering mechanism, dosing, pharmacogenomics, adverse effects, and monitoring of nortriptyline.
- Alexanderson B. Pharmacokinetics of nortriptyline in man after single and multiple oral doses. Eur J Clin Pharmacol. 1972;4(2):82–91. DOI Foundational PK study establishing Vd (21–31 L/kg) and steady-state prediction from single-dose kinetics.
- Dawling S, Crome P, Braithwaite R. Pharmacokinetics of single oral doses of nortriptyline in depressed elderly hospital patients and young healthy volunteers. Clin Pharmacokinet. 1980;5(4):394–401. DOI Demonstrated prolonged half-life and reduced clearance in elderly patients compared with younger volunteers.
- Dawling S, Lynn K, Rosser R, Braithwaite R. The pharmacokinetics of nortriptyline in patients with chronic renal failure. Br J Clin Pharmacol. 1981;12(1):39–45. PMC Showed that chronic renal failure does not significantly alter nortriptyline clearance, but caution is still warranted due to metabolite accumulation.