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Product Name:
CAS Number:
For the treatment of depression.
Mode of Action:

Trazodone binds at 5-HT2 receptor, it acts as a serotonin agonist at high doses and a serotonin antagonist at low doses. Like fluoxetine, trazodone's antidepressant activity likely results from blockage of serotonin reuptake by inhibiting serotonin reuptake pump at the presynaptic neuronal membrane. If used for long time periods, postsynaptic neuronal receptor binding sites may also be affected. The sedative effect of trazodone is likely the result of alpha-adrenergic blocking action and modest histamine blockade at H1 receptor. It weakly blocks presynaptic alpha2-adrenergic receptors and strongly inhibits postsynaptic alpha1 receptors. Trazodone does not affect the reuptake of norepinephrine or dopamine within the CNS.


Trazodone is an antidepressant and hypnotic chemically unrelated to tricyclic, tetracyclic, or other known antidepressant agents. The mechanism of trazodone's antidepressant action in man is not fully understood. In animals, trazodone selectively inhibits serotonin uptake by brain synaptosomes and potentiates the behavioral changes induced by the serotonin precursor, 5-hydroxytryptophan. Cardiac conduction effects of trazodone in the anesthetized dog are qualitatively dissimilar and quantitatively less pronounced than those seen with tricyclic antidepressants. Trazodone is not a monoamine oxidase inhibitor and, unlike amphetamine-type drugs, does not stimulate the central nervous system. In man, trazodone is well absorbed after oral administration without selective localization in any tissue. Since the clearance of trazodone from the body is sufficiently variable, in some patients trazodone may accumulate in the plasma.


Undergoes extensive hepatic metabolism via hydroxylation, N-dealkylation, N-oxidation and splitting of the pyridine ring. Cytochrome P450 (CYP) 3A4 catalyzes the formation of the major active metabolite, m-chlorophenylpiperazine (m-CPP). Metabolites may be further conjugated to glucuonic acid or glutathione. CYP2D6 is responsible for 4'-hydroxylation of m-CPP and the formation of at least one glutathione conjugates of m-CPP, a quinone imine-sulhydryl adduct. Oxotriazolopyridinpropionic acid, an inactive metabolite, and its conjugates account for about 20% of the total excreted oral dose. Less than 1% of the oral dose is excreted unchanged. Approximately 70-75% of the dose is eliminated in urine with the remainder being excreted in feces via biliary elimination.


LD50=96mg/kg (i.v. in mice)

2-{3-[4-(3-chlorophenyl)piperazin-1-yl]propyl}-2H, 3H-[1, 2, 4]triazolo[4, 3-a]pyridin-3-one
DB00656 (APRD00533)
Molecular Mass:
Trazodona [INN-Spanish] Trazodone Hcl Trazodone Hydrochloride Trazodonum [INN-Latin]
AHFS Code:
General Reference:
General Reference:

  1. Marek GJ, McDougle CJ, Price LH, Seiden LS: A comparison of trazodone and fluoxetine: implications for a serotonergic mechanism of antidepressant action. Psychopharmacology (Berl). 1992;109(1-2):2-11. Pubmed
  2. Jauch R, Kopitar Z, Prox A, Zimmer A: [Pharmacokinetics and metabolism of trazodone in man (authorês transl)] Arzneimittelforschung. 1976;26(11):2084-9. Pubmed
  3. Rotzinger S, Fang J, Baker GB: Trazodone is metabolized to m-chlorophenylpiperazine by CYP3A4 from human sources. Drug Metab Dispos. 1998 Jun;26(6):572-5. Pubmed
  4. Kalgutkar AS, Henne KR, Lame ME, Vaz AD, Collin C, Soglia JR, Zhao SX, Hop CE: Metabolic activation of the nontricyclic antidepressant trazodone to electrophilic quinone-imine and epoxide intermediates in human liver microsomes and recombinant P4503A4. Chem Biol Interact. 2005 Jun 30;155(1-2):10-20. Epub 2005 Apr 18. Pubmed
  5. Otani K, Yasui N, Kaneko S, Ishida M, Ohkubo T, Osanai T, Sugawara K, Fukushima Y: Trazodone treatment increases plasma prolactin concentrations in depressed patients. Int Clin Psychopharmacol. 1995 Jun;10(2):115-7. Pubmed
  6. Saletu-Zyhlarz GM, Abu-Bakr MH, Anderer P, Gruber G, Mandl M, Strobl R, Gollner D, Prause W, Saletu B: Insomnia in depression: differences in objective and subjective sleep and awakening quality to normal controls and acute effects of trazodone. Prog Neuropsychopharmacol Biol Psychiatry. 2002 Feb;26(2):249-60. Pubmed
  7. Fink HA, MacDonald R, Rutks IR, Wilt TJ: Trazodone for erectile dysfunction: a systematic review and meta-analysis. BJU Int. 2003 Sep;92(4):441-6. Pubmed

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