Tranylcypromine
Indications
| Indication | Approved Population | Therapy Type | Status |
|---|---|---|---|
| Major Depressive Disorder (MDD) | Adults who have not responded adequately to other antidepressants | Second-line or later monotherapy | FDA Approved |
Tranylcypromine is a non-hydrazine, irreversible MAOI structurally related to amphetamine (a cyclopropylamine derivative), first approved in 1961. The updated 2023 PI explicitly states it is indicated for MDD in adults who have not responded adequately to other antidepressants and is not intended for initial treatment of MDD due to the potential for serious adverse reactions, drug interactions, and the need for dietary restrictions. Despite these constraints, tranylcypromine remains a highly effective antidepressant, and some clinicians prefer it over phenelzine because of its more activating profile and potentially faster onset of action.
Atypical depression — Well-established efficacy particularly when psychomotor retardation or endogenous features are present; may be preferred over phenelzine in this subtype. (Evidence quality: Moderate)
Treatment-resistant depression — Used after failure of SSRIs, SNRIs, and TCAs; meta-analyses support efficacy comparable to TCAs. (Evidence quality: Moderate)
Social anxiety disorder — Evidence extrapolated from phenelzine data and clinical experience. (Evidence quality: Low)
Panic disorder — Used when first-line agents fail. (Evidence quality: Low)
Dosing
Adult Dosing by Clinical Scenario
| Clinical Scenario | Starting Dose | Maintenance Dose | Maximum Dose | Notes |
|---|---|---|---|---|
| MDD — treatment-resistant | 30 mg/day in divided doses | 30–60 mg/day | 60 mg/day (30 mg BID) | If no response by 2 weeks, increase by 10 mg/day every 1–3 weeks Improvement may be seen within 48 h to 3 weeks (per PI); administer earlier in day to reduce insomnia |
| Atypical depression (off-label) | 10–20 mg/day | 30–60 mg/day | 60 mg/day | May be preferred over phenelzine when psychomotor retardation predominates More activating profile; amphetamine-like structure may provide early energy boost |
| Anxiety disorders (off-label) | 10 mg BID | 30–40 mg/day | 60 mg/day | Lower doses often sufficient for anxiolytic effect At doses >40 mg, norepinephrine reuptake inhibition adds to pharmacological profile |
Special Population Adjustments
| Population | Starting Dose | Maintenance Dose | Maximum Dose | Notes |
|---|---|---|---|---|
| Elderly (≥65 years) | 10 mg QD | Titrate cautiously | Individualize (lower doses) | Greater risk of postural hypotension and other serious adverse reactions More gradual dosage increases per PI |
| Hepatic impairment | Use caution; no specific guidance | Sedation reported in patients with cirrhosis; monitor for increased CNS adverse reactions (PI Section 5.10) | ||
| Renal impairment | Use caution; no specific guidance | Manufacturer labelling does not provide dose adjustments | ||
Tranylcypromine is a non-hydrazine MAOI structurally related to amphetamine. It has a much shorter plasma half-life (~2.5 h vs ~11.6 h for phenelzine) and a somewhat shorter duration of MAO inhibition after discontinuation (~10 days vs ~14–21 days for phenelzine). At higher doses (40–60 mg/day), it additionally inhibits norepinephrine reuptake, producing a more activating profile. Postural hypotension is the major dose-limiting side effect above 30 mg/day. Unlike phenelzine, it does not deplete vitamin B6 (since it is not a hydrazine), and hepatotoxicity appears to be less common.
Tranylcypromine Pharmacology
Mechanism of Action
Tranylcypromine is a non-selective, irreversible inhibitor of both MAO-A and MAO-B at therapeutic doses (20–30 mg/day). By inactivating these enzymes, it prevents the degradation of serotonin, norepinephrine, dopamine, and trace amines (particularly phenylethylamine) in the brain and periphery. At higher doses (40–60 mg/day), tranylcypromine additionally inhibits norepinephrine reuptake, an action related to its structural similarity to amphetamine. It also increases brain GABA-B receptor density and modulates phospholipid metabolism. The increase in trace amines, particularly phenylethylamine (which acts as an endogenous amphetamine-like releasing agent), may contribute to its activating properties and potentially faster onset of action compared with phenelzine. Tranylcypromine also inhibits lysine-specific demethylase 1 (LSD1), an epigenetic regulator — a property being investigated in oncology.
ADME Profile
| Parameter | Value | Clinical Implication |
|---|---|---|
| Absorption | Rapidly absorbed; Tmax 1–2 h (biphasic absorption possible with secondary peak at 2–3 h); Cmax 50–200 ng/mL after 20 mg | Fast absorption supports twice-daily dosing; administer morning and early afternoon to minimise insomnia |
| Distribution | Vd 1.1–5.7 L/kg; protein binding high (not precisely characterised) | Wide interindividual variability in distribution; amphetamine-like structure may contribute to CNS penetration |
| Metabolism | Hepatic; metabolites include 4-hydroxytranylcypromine and N-acetyltranylcypromine (less potent MAO inhibitors); inhibits CYP2A6 at therapeutic doses; does not significantly inhibit other CYP enzymes | CYP2A6 inhibition may increase plasma nicotine levels in smokers; low potential for pharmacokinetic interactions with most drugs via CYP pathways |
| Elimination | Plasma t½ ~2.5 h (range 1.5–3.2 h); excretion primarily urinary, rapid within 24 h; MAO inhibition persists up to 10 days after last dose | Short plasma half-life is clinically misleading — irreversible MAO inhibition far outlasts drug presence; dietary/drug restrictions must continue for ≥2 weeks after stopping (PI Section 5.2) |
Side Effects
The updated Parnate PI (revised 11/2023) provides frequency categories from clinical trial data. The most common adverse reactions (>30%) were dry mouth, dizziness, insomnia, sedation, and headache. Adverse reactions occurring in >10% additionally include overexcitement, constipation, blurred vision, and tremor.
| Adverse Effect | Frequency Category | Clinical Note |
|---|---|---|
| Dry mouth | >30% | Anticholinergic-like effect; encourage oral hygiene, sugar-free gum (PI Section 6) |
| Dizziness | >30% | Orthostatic component; postural hypotension is a major side effect above 30 mg/day and may cause syncope (PI Section 5.5) |
| Insomnia | >30% | Related to activating/amphetamine-like properties; administer doses earlier in the day (PI Section 6) |
| Sedation / drowsiness | >30% | Paradoxically coexists with insomnia in some patients; caution with driving (PI Section 5.14) |
| Headache | >30% | Headaches without BP elevation reported; ALWAYS rule out hypertensive crisis if sudden occipital headache (PI Sections 5.2, 6) |
| Adverse Effect | Frequency Category | Clinical Note |
|---|---|---|
| Overexcitement / stimulation | >10% | Amphetamine-like activation; may require dose reduction; assess for hypomania (PI Sections 5.4, 6) |
| Constipation | >10% | Increase fibre and fluids (PI Section 6) |
| Blurred vision | >10% | Rule out angle closure if eye pain; nystagmus also reported (PI Section 6) |
| Tremor | >10% | Fine postural tremor; dose-related; myoclonic jerks also reported (PI Section 6) |
| Adverse Effect | Clinical Note |
|---|---|
| Postural hypotension / syncope | Major dose-limiting adverse effect above 30 mg/day; may result in syncope; monitor standing BP (PI Section 5.5) |
| Weight gain | Significant anorexia also reported; metabolic effects variable (PI Section 6) |
| Sexual dysfunction (impotence, delayed ejaculation) | Serotonergic effect; impacts adherence (PI Section 6) |
| Tachycardia / palpitations | Cardiovascular; obtain ECG if symptomatic (PI Section 6) |
| Edema | Peripheral; may respond to dose reduction (PI Section 6) |
| Paresthesia / numbness | Unlike phenelzine, not related to vitamin B6 depletion (non-hydrazine) (PI Section 6) |
| Anorexia | Significant; may be related to amphetamine-like properties (PI Section 6) |
| Urinary retention / frequency / incontinence | Genitourinary effects; assess for obstruction (PI Section 6) |
| Adverse Effect | Estimated Frequency | Typical Onset | Required Action |
|---|---|---|---|
| Hypertensive crisis | Rare (with proper diet); potentially fatal | Minutes to hours after tyramine ingestion or drug interaction | Discontinue immediately; treat hypertensive emergency; ED admission (PI Section 5.2) |
| Serotonin syndrome | Rare (with contraindicated drug); potentially fatal | Hours after exposure to serotonergic agent | Discontinue all serotonergic agents; supportive care; cyproheptadine (PI Section 5.3) |
| Suicidal ideation / behaviour | Uncommon (age-dependent) | First weeks to months | Close monitoring especially <25 years; consider stopping if emergent suicidality (PI Section 5.1) |
| Hepatitis / elevated aminotransferases | Rare | Weeks to months | Monitor LFTs; discontinue if hepatotoxicity signs develop (PI Section 5.10) |
| Mania / hypomania | Uncommon | First weeks | Discontinue; screen for bipolar disorder (PI Section 5.4) |
| Seizures | Rare (reported with withdrawal and overdose) | Variable | Manage per protocol; monitor at-risk patients (PI Section 5.11) |
| SIADH / hyponatraemia | Rare | Weeks | Check sodium; fluid restriction; discontinue if severe (PI Section 6) |
| Agranulocytosis / blood dyscrasias | Very rare | Variable | Check FBC; discontinue if significant cytopaenia (PI Section 6) |
Hypertensive emergencies (BP >180/120 mmHg with organ dysfunction) may present with severe occipital headache, palpitations, neck stiffness, nausea, sweating, dilated pupils, photophobia, and chest pain. Seizures and intracranial haemorrhage (sometimes fatal) have been reported. All patients must carry a list of prohibited foods and drugs, and should be instructed to seek emergency care immediately if they develop sudden severe headache. The PI contains two boxed warnings — one for suicidality and one specifically for hypertensive crisis with tyramine (PI Section 5.2).
Drug Interactions
Tranylcypromine has an extensive contraindicated drug list (PI Tables 1, 3, and 4). Because MAO inhibition persists up to 10 days after discontinuation, interactions can occur even after the drug is stopped. Unlike phenelzine, tranylcypromine inhibits CYP2A6 at therapeutic concentrations but has low potential for other CYP-mediated interactions.
Monitoring
- Blood PressureBaseline; every visit; orthostatic during titration
RoutinePostural hypotension is a major side effect above 30 mg/day. Also monitor for hypertensive episodes (sudden headache, palpitations) that may indicate dietary non-compliance. Assess BP before prescribing per PI Section 2.4. - Liver FunctionBaseline; periodically
RoutineHepatitis and elevated aminotransferases reported. Discontinue if signs/symptoms of hepatotoxicity develop. Monitor for sedation in patients with cirrhosis (PI Section 5.10). - Mental StateEvery visit for first 3 months
RoutineMonitor for suicidality, mania/hypomania, psychosis, overexcitement, and anxiety aggravation. Screen for bipolar disorder before initiation (PI Sections 5.1, 5.4, 5.13). - Dietary ComplianceEvery visit
RoutineReview tyramine-restricted diet and medication restrictions. Ensure patient has written list and understands the 2-week post-discontinuation restriction period. - WeightBaseline, then every 3 months
RoutineBoth weight gain and significant anorexia reported. Monitor in both directions. - Blood GlucoseIf diabetic
Trigger-BasedMAOIs may contribute to hypoglycaemia in diabetic patients (PI Section 5.12). - Renal FunctionBaseline
RoutineNo specific guidance in PI, but renal function should be assessed given primary urinary excretion.
Contraindications & Cautions
Absolute Contraindications
- Pheochromocytoma or catecholamine-releasing paraganglioma (PI Section 4.2)
- Concomitant or recent use of contraindicated drugs (PI Table 1): other MAOIs, SSRIs, SNRIs, TCAs, bupropion, triptans, sympathomimetics, amphetamines, meperidine, dextromethorphan, carbamazepine, cyclobenzaprine, buspirone, levodopa, methyldopa, dopamine, tryptophan, SAM-e, rasagiline, tetrabenazine, tapentadol, non-selective H1 antihistamines
- Tyramine-containing foods and beverages during treatment and for 2 weeks after
Relative Contraindications (Specialist Input Recommended)
- Bipolar disorder (unscreened) — risk of manic switching (PI Section 5.4)
- Hyperthyroidism — greater risk of hypertensive crisis (PI Section 5.2)
- Cerebrovascular or cardiovascular disease — increased risk from hypertensive complications
- Hepatic impairment — sedation in cirrhosis; hepatitis reported (PI Section 5.10)
Use with Caution
- Elderly — greater risk of postural hypotension and other serious reactions; start at lower doses
- Patients at risk of suicide — prescribe smallest feasible quantity; MAOI overdose is frequently fatal
- Patients requiring surgery — discontinue at least 10 days before elective surgery (PI Section 5.6)
- Diabetic patients — hypoglycaemia risk (PI Section 5.12)
- History of drug abuse — abuse potential at high doses due to amphetamine-like structure (reported at 120–600 mg/day)
Antidepressants increase the risk of suicidal thinking and behaviour in paediatric and young adult patients. Risk was 14 additional patients per 1,000 treated (<18 years) and 5 additional per 1,000 (18–24 years). Tranylcypromine is not approved for paediatric use. Monitor all patients closely.
2. Hypertensive Crisis with TyramineExcessive consumption of foods or beverages with significant tyramine content, or use of certain drugs, can precipitate hypertensive crisis during tranylcypromine treatment or after discontinuation. Monitor blood pressure, allow for medication-free intervals, and advise patients to avoid high-tyramine foods and beverages.
Patient Counselling
Purpose of Therapy
Tranylcypromine works by blocking an enzyme (monoamine oxidase) that breaks down mood-regulating brain chemicals. This allows serotonin, norepinephrine, and dopamine to build up and improve mood. It is prescribed when other antidepressants have not worked. The medication requires strict dietary restrictions because certain foods can cause a dangerous blood pressure spike.
How to Take
Take tranylcypromine in divided doses, typically in the morning and early afternoon to reduce the risk of insomnia. It may take up to 3 weeks to notice improvement, though some patients respond within days. Do not stop the medication abruptly — your doctor will reduce the dose gradually.
Sources
- Parnate (tranylcypromine) Tablets — Full Prescribing Information. Revised November 2023. DailyMedPrimary source for FDA-approved indication, dosing, adverse reactions (with frequency categories), contraindications, and drug/food interactions. Modern label format with Tables 1–4 for interactions.
- Himmelhoch JM, Thase ME, Mallinger AG, Houck P. Tranylcypromine versus imipramine in anergic bipolar depression. Am J Psychiatry. 1991;148(7):910–916. DOIKey trial demonstrating tranylcypromine superiority over imipramine in anergic bipolar depression.
- Thase ME, Trivedi MH, Rush AJ. MAOIs in the contemporary treatment of depression. Neuropsychopharmacology. 1995;12(3):185–219. DOIComprehensive review and meta-analysis of MAOI efficacy in depression, including tranylcypromine comparison with TCAs.
- Laux G, Volz HP, Möller HJ. Newer and older monoamine oxidase inhibitors: a comparative profile. CNS Drugs. 1995;3(2):145–158. DOIComparative review of MAOIs including tranylcypromine, with efficacy and side-effect data.
- American Psychiatric Association. Practice guideline for the treatment of patients with major depressive disorder, 3rd ed. Am J Psychiatry. 2010;167(10 Suppl):1–152. DOIAPA guideline recommending MAOIs for treatment-resistant depression after failure of multiple first-line agents.
- Bauer M, Pfennig A, Severus E, et al. World Federation of Societies of Biological Psychiatry (WFSBP) guidelines for biological treatment of unipolar depressive disorders. World J Biol Psychiatry. 2013;14(5):334–385. DOIInternational guideline positioning MAOIs as a treatment option in refractory depression with evidence-graded recommendations.
- Schildkraut JJ. The catecholamine hypothesis of affective disorders: a review of supporting evidence. Am J Psychiatry. 1965;122(5):509–522. DOIFoundational paper establishing the monoamine hypothesis of depression that underpins MAOI pharmacology.
- Bortolato M, Chen K, Shih JC. Monoamine oxidase inactivation: from pathophysiology to therapeutics. Adv Drug Deliv Rev. 2008;60(13–14):1527–1533. DOIComprehensive review of MAO biochemistry and the pharmacological basis of irreversible MAO inhibition.
- Schiebeler H, Laux G, Möller HJ. Tranylcypromine in mind (Part I): review of pharmacology. Eur Neuropsychopharmacol. 2017;27(8):697–713. DOIDefinitive 2017 review of tranylcypromine pharmacodynamics, pharmacokinetics, drug interactions, and toxicology. Source for plasma t½ 2 h, pharmacodynamic t½ ~1 week, and CYP2A6 inhibition data.
- Mallinger AG, Edwards DJ, Himmelhoch JM, Knopf S, Ehler J. Pharmacokinetics of tranylcypromine in patients who are depressed: relationship to cardiovascular effects. Clin Pharmacol Ther. 1986;40(4):444–450. DOIPK study in depressed patients linking tranylcypromine plasma levels to hypotensive effects and clinical outcome.
- Gillman PK. Monoamine oxidase inhibitors, opioid analgesics and serotonin toxicity. Br J Anaesth. 2005;95(4):434–441. DOIDefinitive review of MAOI-opioid interactions, clarifying which opioids are safe and which are contraindicated.
- StatPearls: Tranylcypromine. In: StatPearls [Internet]. Treasure Island, FL: StatPearls Publishing; updated January 19, 2025. NCBI BookshelfPeer-reviewed clinical summary covering indications, PK (Vd 1.1–5.7 L/kg, t½ 1.5–3.2 h), adverse effects, and monitoring.