Trazodone: Effect on Depression and Sleep Disorders

Trazodone (brand names including Trittico, Thombran and generics) is an antidepressant from the group of serotonergic antagonists and reuptake inhibitors (SARI). In Germany, trazodone is approved for the treatment of depressive disorders with or without accompanying anxiety disorder. Due to its strong sedating properties, the active substance is additionally often used off-label at low doses for sleep disorders, particularly in patients with depression, concurrent sleep problems, or with a history of substance use, where benzodiazepines should be avoided.

Trazodone differs from classical SSRIs in its profile. It not only improves mood but also shortens sleep latency, improves sleep continuity, and disrupts sexual function much less frequently than SSRIs. On the other hand, daytime drowsiness, orthostatic complaints, and interactions with other serotonergic substances are drawbacks. Careful indication assessment is worthwhile because trazodone shows its strengths especially when sleep problems are in the foreground.

Mechanism of Action

Trazodone is a multimodal acting antidepressant. At low to moderate doses, it potently blocks the serotonin 5-HT2A receptor, antagonizes alpha 1 adrenoreceptors, and blocks histamine H1 receptors, which together explain the pronounced sedating effect. At higher doses, inhibition of the serotonin reuptake transporter (SERT) is added. This increases the synaptic availability of serotonin, which mediates the actual antidepressant effect.

The dual profile explains why trazodone at low doses (approximately 25 to 100 mg at night) primarily acts as a sleep aid, while the antidepressant effect occurs reliably only at doses from 150 mg per day. The active metabolite meta-chlorphenylpiperazine (mCPP) is produced via CYP3A4 and has its own serotonergic effect. This metabolite explains some side effects such as nausea or headaches, especially in combination with CYP3A4 inhibitors.

The half-life of trazodone is three to six hours, with extended-release formulations prolonging the duration of action. Significant anticholinergic effect is absent, making trazodone better tolerated compared to tricyclics in older people. Full antidepressant effect typically occurs after two to four weeks.

Indications

• Depressive episodes with or without accompanying anxiety disorder, especially with concurrent sleep disorder
• Sleep disorders in depression, low-dose, often as add-on to an SSRI or SNRI
• Off-label for chronic sleep disorders, particularly in patients at risk for benzodiazepine dependence or with substance use history
• Off-label for sleep disorders in elderly, with cautious dosing due to orthostatic hypotension
• Adjunctive for irritability, aggression, or sleep problems in dementia, individual assessment due to fall risk

Trazodone is not first choice for acute suicidal crises, severe bipolar depression, or in patients with clinically relevant QT prolongation. In younger patients with depression, SSRIs are usually the initial standard therapy.

Dosage and Administration

For depression: Start with 50 to 100 mg at night, slow increase in steps of 50 mg every three to four days up to a target dose of 150 to 300 mg per day. Higher doses up to 600 mg per day possible in inpatient treatment, typically maximum 400 mg in outpatient care.

For sleep disorders (off-label): 25 to 100 mg approximately 30 to 60 minutes before bedtime. Due to very individual sensitivity, it is recommended to start with 25 mg and increase slowly.

Administration: Ideally with or shortly after a meal, as this reduces nausea and dizziness. Extended-release tablets must not be crushed, regular tablets are partially divisible (observe break line).

Renal insufficiency: Generally no dose adjustment required. Hepatic insufficiency: Cautious dose adjustment in impaired liver function, in severe insufficiency therapy decision is individual. Elderly patients: Halve starting dose, slower dose escalation due to fall risk.

Side Effects

Very common: Drowsiness, daytime sleepiness, dizziness, dry mouth, headaches.

Common: Orthostatic hypotension with dizziness on standing, lightheadedness, nausea, constipation, blurred vision, restlessness, tremor.

Occasional to rare: Cardiac conduction disturbances with QT prolongation, tachycardia, arrhythmias, allergic skin reactions, hyponatremia (especially in elderly patients), liver enzyme elevation.

Rare but relevant: Priapism, a painful erection lasting longer than four hours. This cardiac emergency requires immediate urological treatment, otherwise permanent erectile dysfunction threatens. Patients must be explicitly informed about this at therapy initiation.

Suicidality: In the first weeks of any antidepressant therapy, suicide risk in younger adults may be temporarily increased. Close medical supervision is part of safe treatment.

Drug Interactions

• CYP3A4 inhibitors (erythromycin, clarithromycin, ketoconazole, itraconazole, ritonavir, grapefruit juice): increased trazodone levels, more sedation and hypotension.
• CYP3A4 inducers (carbamazepine, phenytoin, rifampicin, St. John's wort): reduced trazodone levels, efficacy may decrease.
• SSRIs, SNRIs, MAO inhibitors, tricyclics, triptans, tramadol, linezolid, methylene blue: Increased risk of serotonin syndrome, combination only with caution.
• Antihypertensives: Additive hypotension, falls possible.
• QT prolonging drugs (amiodarone, sotalol, citalopram at higher doses, methadone, some antibiotics and antifungals): cumulative risk for torsade de pointes.
• Alcohol, benzodiazepines, Z substances, first-generation antihistamines: Enhanced central depression, respiratory depression possible.
• Digoxin, phenytoin: Level changes possible, monitoring recommended.

Special Notes

Pregnancy: Data limited. When indication is compelling, benefit-risk assessment, preferred preparations are usually SSRIs with better data available. Breastfeeding: Transition into breast milk in small amounts, individual decision in consultation with pediatrician and psychiatrist.

Children and adolescents: No approval. Use only in specialized centers and individual exceptions.

Cardiac preexisting conditions: ECG before therapy initiation in patients with risk factors such as bradycardia, electrolyte disturbances, structural heart disease, syncope history, or familial QT prolongation. Consider ECG monitoring during therapy as well, especially with dose escalation.

Discontinuation: Do not abruptly stop trazodone, instead taper over at least two weeks to avoid discontinuation phenomena such as sleep disorders, irritability, dizziness, or flu-like symptoms.

Driving ability: Often impaired during titration phase and the following day. Patients should avoid activities with fall or accident risk in the first days.

You Might Also Be Interested In

• Agomelatine, melatonergic antidepressant with good sleep profile
• Paroxetine, SSRI for depression and anxiety disorder
• Zolpidem, Z substance for short-term sleep onset disorders
• Tryptophan, amino acid to support sleep
• Donepezil, cholinesterase inhibitor for dementia-related behavioral disturbances

Frequently Asked Questions

Sources

• Gelbe Liste, Trazodone active substance profile
• BfArM, Federal Institute for Drugs and Medical Devices
• AWMF, S3 Guideline Unipolar Depression
• EMA, European Medicines Agency