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Changes: Trazodone


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Latest revision as of 00:49, November 14, 2010



Trazodone chemical structure


IUPAC name
CAS number
ATC code


Chemical formula {{{chemical_formula}}}
Molecular weight 371.864 g/mol
Bioavailability High
Metabolism Hepatic
Elimination half-life 3-6 hours
Excretion 20% feces,
80% urine
Pregnancy category USA: C
Legal status Unscheduled;
Rx only
Routes of administration Oral

Trazodone (Desyrel®, Trittico®, Thombran®, Trialodine®) is a psychoactive compound with sedative, anxiolytic, and antidepressant properties. The manufacturer claims that the antidepressant activity becomes evident in the first week of therapy. Trazodone has less prominent anticholinergic (dry mouth, constipation, tachycardia) and adrenolytic (hypotension, male sexual problems) side effects than most tricyclic antidepressants. The incidence of nausea and vomiting observed with Trazodone is relatively low compared to SSRIs.

Mechanism of actionEdit

Trazodone is a serotonin reuptake inhibitor and is also a 5-HT2 receptor antagonist. However, in contrast to the selective serotonin reuptake inhibitors such as fluoxetine (Prozac®), trazodone's antidepressant effects may be due to its antagonistic effect at the 5-HT2 receptor site (PMID 1365657).


Trazodone is well absorbed after oral administration with mean peak blood levels obtained at approximately 1 hour after ingestion. Absorption is somewhat delayed and enhanced by food. The mean blood elimination half-life is biphasic: the first phase's half-life is 3-6 hours, and the following phase's half-life is 5-9 hours. The drug is extensively metabolized with 3 or 4 major metabolites having been identified in man, some of which such as mCPP may contribute to the side effect profile of trazodone. Approximately 70-75% of C14-labelled trazodone was found to be excreted in the urine within 72 hours (PMID 1037253). Trazodone is highly protein-bound.




Trazodone is metabolised by CYP3A4, a liver enzyme (PMID 9616194). Inhibition of this enzyme by various other substances may delay its degradation, leading to high blood levels of trazodone. CYP3A4 may be inhibited by many other medications, herbs, and foods, and as such, trazodone may interact with these substances. One drug-food interaction is grapefruit juice. Drinking grapefruit juice is discouraged in patients taking trazodone. One glass of grapefruit juice once in a while is not likely to have this effect on most people, but drinking large amounts, or drinking it regularly is proven to.


Episodes of complex partial seizures have been reported in a small number of patients. The majority of these patients were already receiving anticonvulsant therapy for a previously diagnosed seizure disorder.

While trazodone is not a true member of the SSRI class of antidepressants, it does still share many properties of the SSRIs, especially the possibility of discontinuation syndrome if the medication is stopped too quickly. Care must therefore be taken when coming off the medication, usually by a gradual process of tapering down the dose over a period of time.

Pregnancy and LactationEdit

  • Pregnancy : Sufficient data in humans is lacking. The use should be justified by the severity of the condition to be treated.
  • Lactation : Sufficient data in humans is also lacking. Additionally, trazodone may be found in the maternal milk in significant concentrations. The use in breastfeeding women should be carefully weighed against possible risks.

Side effectsEdit





Tremor, headache, ataxia, akathisia, muscle stiffness, slurred speech, slowed speech, vertigo, tinnitus, tingling of extremities, paresthesia, weakness, complex partial seizures, and, rarely impaired speech, muscle twitching, numbness, dystonia and involuntary movements.





Rare Side EffectsEdit





Rare cases of idiosyncratic hepatotoxicity have been observed, possibly due to the formation of reactive metabolites (PMID 15978881).



Elevated prolactin concentrations have been observed in patients taking trazodone (PMID 7673654).


Allergic or toxicEdit




Occupational HazardsEdit


Laboratory testsEdit


Drug InteractionsEdit










Overdosage of trazodone may cause an increase in incidence or severity of any of the reported adverse reactions, e.g. hypotension and excessive sedation. Death by deliberate or accidental overdosage has been reported (PMID 15975258, PMID 11603256).



See alsoEdit


External linksEdit

Antidepressants (ATC N06A) edit
Reversible inhibitor of monoamine oxidase A (RIMA) Brofaromine, Moclobemide
Norepinephrine-dopamine reuptake inhibitors Bupropion
Selective serotonin reuptake enhancer (SSRE) Tianeptine
Tetracyclic antidepressants Maprotiline, Mianserin, Nefazodone, Trazodone
Noradrenergic and specific serotonergic antidepressant (NaSSA) Mirtazapine

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