Molecule

Drug Groups

approved; investigational

Description

A serotonin uptake inhibitor that is used as an antidepressive agent. It has been shown to be effective in patients with major depressive disorders and other subsets of depressive disorders. It is generally more useful in depressive disorders associated with insomnia and anxiety. This drug does not aggravate psychotic symptoms in patients with schizophrenia or schizoaffective disorders. (From AMA Drug Evaluations Annual, 1994, p309)

Indication

For the treatment of depression.

Pharmacology

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.

Toxicity

LD₅₀=96mg/kg (i.v. in mice)

Affected Organisms

Biotransformation

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.

Absorption

Rapidly and almost completely absorbed following oral administration. Food may decrease the rate and extent of absorption.

Half Life

Undergoes biphasic elimination with an initial phase t_{1/2 α} of 3-6 hours and a terminal phase t_{1/2 β} of 5-9 hours.

Protein Binding

89-95% bound to plasma proteins in vitro

References

External Links