Adult: Initially, 75 mg daily; may be increased to 300 mg daily if necessary. Treatment recommendations may vary among countries and between individual products (refer to specific product guidelines).
Oral Major depressive disorder
Adult: Initially, 150 mg daily; may be increased by 50 mg daily every 3-4 days depending on clinical response and patient's tolerance. Max: 300-400 mg daily. Doses may be given in divided doses after meals or as a single dose at bedtime. For severe cases in hospitalised patients: Up to 600 mg daily in divided doses. Use the lowest effective dose. Dosage recommendations may vary among countries and between individual products (refer to specific product guidelines). Elderly: Initially, 100 mg daily; may be increased to 300 mg daily depending on clinical response and patient's tolerance. Doses may be given in divided doses or as a single dose at bedtime. Use the lowest effective dose. Dosage and treatment recommendations may vary among countries and between individual products (refer to specific product guidelines).
What are the brands available for Trazodone in Hong Kong?
Trittico
Trittico Prolonged-release
Administration
Trazodone Should be taken with food.
Contraindications
Acute MI. Concomitant use with or within 14 days of discontinuing MAOIs intended to treat psychiatric disorders. Concomitant use with linezolid or IV methylthioninium chloride (methylene blue).
Special Precautions
Patient with history of suicidal-related events or a significant degree of suicidal ideation, history of bipolar disorder, seizure disorder or at risk of seizures (e.g. history of seizures, head trauma, brain damage, alcoholism), cardiac disease (e.g. angina pectoris, conduction disorders or different degrees of AV block, congenital long QT syndrome, bradycardia), micturition disorders (e.g. prostate hypertrophy), acute narrow-angle glaucoma, increased IOP, hyperthyroidism, risk factors for priapism (e.g. sickle cell anaemia, multiple myeloma, leukaemia, anatomical deformation of penis). Avoid abrupt withdrawal. Renal and hepatic impairment (particularly severe cases). Elderly. Pregnancy and lactation.
Adverse Reactions
Significant: Suicidal thoughts and behaviour (particularly in young adults); may precipitate a mixed/manic episode; cardiac arrhythmias, including prolonged QT interval on ECG (with or without torsades de pointes), ventricular tachycardia, sinus bradycardia, 1st-degree AV block, and complete AV block; may increase risk of bleeding; CNS depression; orthostatic hypotension, which may lead to syncope; mild pupillary dilation, which may trigger an episode of narrow-angle glaucoma (in susceptible patients); hyponatraemia resulting from SIADH; withdrawal symptoms (mainly upon abrupt discontinuation). Rarely, priapism. Blood and lymphatic system disorders: Agranulocytosis, thrombocytopenia, eosinophilia, leucopenia, anaemia. Eye disorders: Blurred vision. Gastrointestinal disorders: Nausea, vomiting, xerostomia, constipation, diarrhoea. General disorders and administration site conditions: Fatigue, weakness, chest pain, fever, oedema, influenza-like illness. Immune system disorders: Allergic reactions. Investigations: Weight loss or gain. Metabolism and nutrition disorders: Anorexia, increased appetite. Musculoskeletal and connective tissue disorders: Musculoskeletal pain. Nervous system disorders: Dizziness, drowsiness, headache, tremor. Psychiatric disorders: Confusion, insomnia, disorientation, anxiety, agitation, delusions, aggressive reactions, hallucinations, nightmares. Renal and urinary disorders: Micturition disorder. Respiratory, thoracic and mediastinal disorders: Nasal congestion, dyspnoea. Skin and subcutaneous tissue disorders: Rash, pruritus, hyperhidrosis. Vascular disorders: Hypertension. Potentially Fatal: Serotonin syndrome; hepatotoxicity (e.g. acute or fulminant hepatitis, symptomatic jaundice). Rarely, NMS.
This drug may cause drowsiness or sedation, if affected, do not drive or operate machinery.
Monitoring Parameters
Monitor LFTs at baseline and periodically during treatment. Closely monitor for clinical worsening, suicidality or unusual changes in behaviour (particularly during the 1st 1-2 months of treatment or during dose adjustments). Assess for signs or symptoms of orthostasis, hypotension, and serotonin syndrome.
Management: Symptomatic and supportive treatment. Administer activated charcoal or perform gastric lavage within 1 hour of ingestion. Correct acid-base and metabolic disturbances and provide oxygen as required. May give IV diazepam or lorazepam for treatment of frequent or prolonged seizures, or an IV infusion of phenytoin if these measures are not adequate. May administer inotropes (e.g. dopamine, dobutamine) if severe hypotension persists. Monitor blood pressure, pulse, and Glasgow Coma Scale.
Drug Interactions
May increase the risk of bleeding with anticoagulants or antiplatelets (e.g. clopidogrel, warfarin, rivaroxaban, dabigatran). May increase plasma concentration and risk of adverse effects with potent CYP3A4 inhibitors (e.g. ketoconazole, itraconazole, clarithromycin, ritonavir, nefazodone). May reduce serum concentration with CYP3A4 inducers (e.g. carbamazepine, phenytoin). May enhance sedative effects with other CNS depressants (e.g. barbiturates). Increased risk of cardiac arrhythmia with agents that may prolong QT interval (e.g. class IA and III antiarrhythmics, chlorpromazine, gatifloxacin). May increase the serum levels of digoxin or phenytoin. Potentially Fatal: Increased risk of serotonin syndrome with MAOIs (e.g. isocarboxazid, phenelzine, tranylcypromine, linezolid, IV methylthioninium chloride [methylene blue]) and other serotonergic agents (e.g. TCAs, SSRIs, SNRIs, triptans, fentanyl, lithium, tramadol, buspirone, tryptophan). May increase the risk of NMS with neuroleptics.
Food Interaction
Increased absorption, delayed time to peak plasma concentration and decreased peak plasma concentration with food. Increased sedative effects with alcohol. Increased risk of serotonin syndrome with St. John's wort.
Lab Interference
May cause false-positive results for amphetamine/methamphetamine urine test.
Action
Description: Overview: Trazodone is a triazolopyridine derivative antidepressant that is both an SSRI and a serotonin type 2 (5-HT2) receptor antagonist. Mechanism of Action: The mechanism of action of trazodone is not precisely known, but it has been shown to selectively inhibit the reuptake of serotonin (5-HT), while also acting as a 5-HT2A receptor antagonist. Its partial agonist activity at 5-HT1A receptors may provide mild anxiolytic effect. Additionally, it significantly blocks the histamine (H1) and α1-adrenergic receptors. Pharmacodynamics: At low doses, the antagonistic activity of trazodone at H1 and α1-adrenergic receptors may lead to postural hypotension, syncope, and sedation. Trazodone has minimal effects on rapid eye movement (REM) sleep while improving sleep efficiency and subjective sleep quality in depressed patients. It also has minimal effects on the CV system, which may likely be due to its lack of significant anticholinergic activity and catecholamine-potentiating effects. Additionally, trazodone antagonises α2-adrenergic receptors, which may enhance arterial inflow and relax the tissues in penile vascular and corporal smooth muscle, resulting in priapism. Onset: Depression: Within 1-2 weeks (initial effects). Pharmacokinetics: Absorption: Readily absorbed from the gastrointestinal tract. Food increases absorption, delays time to peak plasma concentration and decreases peak plasma concentration. Time to peak plasma concentration: Approx 1 hour (fasting); 2 hours (fed). Distribution: Crosses the placenta; enters breast milk (small amounts). Plasma protein binding: Approx 89-95%. Metabolism: Extensively metabolised in the liver by CYP3A4 via N-oxidation and hydroxylation into m-chlorophenylpiperazine (active metabolite). Excretion: Mainly via urine (74%, <1% as unchanged drug); faeces (approx 21%). Terminal elimination half-life: 5-9 hours.
Chemical Structure
Trazodone Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 5533, Trazodone. https://pubchem.ncbi.nlm.nih.gov/compound/Trazodone. Accessed Nov. 25, 2025.
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