Source: Medicines & Healthcare Products Regulatory Agency (GB) Revision Year: 2018 Publisher: Flamingo Pharma UK Ltd., I<sup>st</sup> floor, Kirkland House, 11-15 Peterborough Road, Harrow, Middlesex, HA12AX, United Kingdom
Pharmacotherapeutic group: Other antidepressants
ATC code: N06AX05
Trazodone hydrochloride is a potent antidepressant. It also has anxiety reducing activity. Trazodone hydrochloride is a triazolopyridine derivative chemically unrelated to known tricyclic, tetracyclic and other antidepressant agents. It has negligible effect on noradrenaline re-uptake mechanisms. Whilst the mode of action of Trazodone hydrochloride is not known precisely, its antidepressant activity may concern noradrenergic potentiation by mechanisms other than uptake blockade. A central antiserotonin effect may account for the drug’s anxiety reducing properties.
Trazodone is rapidly absorbed from the gastro-intestinal tract and extensively metabolised. Paths of metabolism of Trazodone include n-oxidation and hydroxylation. The metabolic m-chlorophenylpiperazine is active. Trazodone is excreted in the urine almost entirely in the form of its metabolites, either in free or in conjugated form. The elimination of Trazodone is biphasic, with a terminal elimination half-life of 5 to 13 hours. Trazodone is excreted in breast milk.
There was an approximate two-fold increase in terminal phase half-life and significantly higher plasma concentrations of Trazodone in 10 subjects aged 65 to 74 years compared with 12 subjects aged 23 to 30 years following a 100mg dose of Trazodone. It was suggested that there is an age-related reduction in the hepatic metabolism of Trazodone.
In vitro studies in human liver microsomes show that trazodone is metabolised by cytochrome P4503A4 (CYP3A4) to form m-chlorophenylpiperazine. Whilst significant, the role of this pathway in the total clearance of trazodone in vivo has not been fully determined.
There are no preclinical data of relevance to the prescriber additional to those already included in other sections of the SmPC.
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