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Comparative table of the main pharmacological therapies for depression
Pharmacotherapy for depressive disorders includes medications with very different mechanisms, indications and safety profiles. Second generation antidepressants are generally the most widely used initial options for major depressive disorder because of their more favorable overall balance of efficacy, tolerability and safety; tricyclics and MAOIs retain an important role in selected patients, whereas antipsychotics and lithium do not constitute a single category of “antidepressants” but are used for specific indications, such as psychotic depression, bipolar depression or augmentation strategies.
The table compares the five pharmacological areas discussed in detail on the dedicated pages. It does not establish a universal ranking: treatment selection depends on diagnosis, severity, previous episodes, psychotic or bipolar features, response to previous treatments, suicide risk, comorbidities, interactions, pregnancy, age, patient preferences and the feasibility of monitoring. Even within the same class, differences between individual agents may be clinically greater than the category name alone would suggest.
| Medication | Mechanism | Use | Contraindications and precautions | Advantages | Limitations |
| Tricyclic antidepressants | Variable inhibition of SERT and NET, combined with muscarinic, H1 and α1 antagonism; some agents have additional receptor actions. | Major depressive disorder in selected patients, especially after lack of efficacy or intolerance of better tolerated options; specific agents have additional indications, such as clomipramine for OCD. | Particular caution is required with conduction disorders, heart disease, anticholinergic risk, glaucoma or urinary retention depending on the agent, drug interactions and overdose risk. | Established antidepressant efficacy; some agents are useful when specific additional indications coexist. | Greater anticholinergic, orthostatic and sedative burden and greater cardiotoxicity in overdose than many newer antidepressants. |
| MAO inhibitors | Inhibition of MAO-A and/or MAO-B, reversible or irreversible depending on the medication, increasing monoamine availability. | Treatment resistant depression and some presentations with atypical features after specialist assessment; the role and availability depend on the specific agent. | Potentially serious interactions with serotonergic or sympathomimetic drugs; irreversible nonselective MAOIs require dietary tyramine restrictions and appropriate washout periods. | They may be effective after multiple treatment failures and retain a role in selected cases of treatment resistant depression. | More complex management, risk of interactions and the need to understand differences among classic MAOIs, moclobemide and formulations available in different countries. |
| Second-generation antidepressants | Heterogeneous group: SERT and/or NET inhibition, receptor antagonism or agonism and other mechanisms depending on whether the agent is an SSRI, SNRI, mirtazapine, bupropion, trazodone, vortioxetine, agomelatine or another medication. | Main pharmacological options for major depressive disorder; selection of the specific agent depends on symptoms, comorbidities, previous treatments, interactions and approved indications. | Precautions are agent specific: serotonin syndrome and MAOI washout, hyponatremia, bleeding, blood pressure, hepatic function, QT interval or seizure risk may be relevant depending on the medication. | Overall favorable efficacy to tolerability balance and lower overdose toxicity than TCAs; broad scope for tailoring the pharmacological profile to the patient. | Response is not guaranteed, and sexual dysfunction and discontinuation symptoms occur with many agents; gastrointestinal effects, insomnia, sedation, weight changes or other specific adverse effects may also occur. |
| Antipsychotics | Dopaminergic and serotonergic modulation with different receptor profiles; some agents are D2 antagonists, whereas others are partial dopamine agonists. | Combination with an antidepressant in psychotic depression; specific agents in bipolar depression; augmentation of treatment for major depressive disorder with medications supported by specific evidence. In Italy, quetiapine XR has a specific adjunctive indication in certain circumstances, whereas other uses may be off label. | Weight and metabolic status, blood pressure, extrapyramidal symptoms and akathisia, prolactin, sedation, QT interval and interactions should be assessed according to the medication and the individual patient. | A central pharmacological component of treatment for psychotic depression; some agents may increase the likelihood of response in treatment resistant depression or treat the depressive phase of bipolar disorder. | Additional benefit must be balanced against metabolic, neurological, endocrine and cardiac adverse effects; the indication cannot be generalized to the entire class. |
| Lithium | Modulates multiple intracellular pathways, including phosphoinositide signaling and GSK-3; its overall clinical mechanism cannot be reduced to a single target. | A cornerstone of maintenance treatment for bipolar disorder and an option in mania; in unipolar major depression it is used mainly as augmentation after an insufficient antidepressant response. | Narrow therapeutic index: requires standardized serum lithium measurement, renal and thyroid function tests, calcium assessment, evaluation of fluid and electrolyte status, and monitoring for interactions with NSAIDs, diuretics, ACE inhibitors and other medications. Pregnancy and kidney disease require specialist assessment. | Strong efficacy in preventing bipolar recurrences and extensive clinical experience; antidepressant augmentation is supported by controlled studies. | Requires ongoing monitoring, has dose dependent toxicity and may cause renal, thyroid, parathyroid and neurological effects; although many data suggest an antisuicidal effect, randomized trials alone are not conclusive. |
How to interpret the clinical comparison
The most important distinction concerns the therapeutic role. SSRIs, SNRIs and other second generation antidepressants are designed and studied as primary antidepressant treatments. Tricyclics are also effective antidepressants, but their tolerability profile and the hazards of overdose often limit their use as first line options. MAOIs can be extremely useful in selected patients, but require expertise in managing interactions and washout periods.
Antipsychotics and lithium must instead be interpreted in relation to the diagnosis. In psychotic depression the combination of an antidepressant and an antipsychotic is supported by guidelines and controlled studies. In bipolar depression, antidepressant monotherapy may be inappropriate in many contexts, whereas some antipsychotics and mood stabilizers have specific supporting evidence. In unipolar major depressive disorder, an antipsychotic or lithium is generally used as an augmentation strategy rather than as an interchangeable substitute for initial antidepressant treatment.
The term treatment resistant depression does not identify a single biological population. Before switching classes or adding a medication, it is necessary to verify diagnostic accuracy, adequacy of treatment dose and duration, adherence, comorbidities, substance use, sleep disorders and possible bipolar or psychotic features. An apparently “resistant” pharmacological course may in fact reflect inadequate treatment exposure or an incomplete diagnostic assessment.
Safety differences are critical. Tricyclics require particular attention to cardiac conduction and overdose risk; MAOIs require careful management of pharmacodynamic and dietary interactions; second generation antidepressants have highly variable profiles and cannot be treated as a homogeneous class; antipsychotics require metabolic and neurological monitoring; and lithium requires monitoring of serum levels, renal and thyroid function and calcium. A single comorbidity can therefore radically alter the benefit to risk balance.
Tolerability affects real world effectiveness because it influences adherence and persistence with treatment. A medication that is statistically effective in a study may be a poor choice for a patient with a predictably problematic adverse effect, whereas a treatment not generally considered first line may become appropriate when the individual history shows a previous robust response and good tolerability.
Discontinuation is another factor that differentiates treatment strategies. Many antidepressants can cause discontinuation symptoms, particularly after rapid cessation; MAOIs require appropriate washout periods before incompatible medications; antipsychotics should be tapered gradually when the clinical situation permits; and lithium should not be stopped abruptly unless urgently necessary because of relapse risk. Discontinuation planning is therefore part of the initial treatment decision rather than a separate issue that arises only at the end of treatment.
Finally, the table does not replace the dedicated pages because many decisions are agent specific. Differences in metabolism, half life, interactions, dosage, regulatory indications and monitoring may be substantial within the same class. The comparison is therefore useful for guiding clinical reasoning among strategies, whereas prescribing requires assessment of the individual medication and its corresponding prescribing information.
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- Agenzia Italiana del Farmaco. Quetiapina a rilascio prolungato: Riassunti delle Caratteristiche del Prodotto. Banca Dati Farmaci AIFA, documentazione vigente consultata nel 2026.
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