Its bioavailability is 65 to 80%. Peak blood levels of trazodone occur 1 to 2 hours after ingestion and peak levels of the metabolite mCPP occur after 2 to 4 hours. Absorption is somewhat delayed and enhanced by food. Distribution
Trazodone is not sequestered into any tissue. The medication is 89 to 95% protein-bound. The volume of distribution of trazodone is 0.8 to 1.5 L/kg. Trazodone is highly lipophilic. Metabolism
The metabolic pathways involved in the metabolism are not well-characterized. In any case, the cytochrome P450 enzymes CYP3A4, CYP2D6, and CYP1A2 may all be involved to varying extents. Trazodone is known to be extensively metabolized by the liver via hydroxylation, N-oxidation, and N-dealkylation. Several metabolites of trazodone have been identified, including a dihydrodiol metabolite (via hydroxylation), a metabolite hydroxylated at the para position of the meta-chlorophenyl ring (via CYP2D6), oxotriazolepyridinepropionic acid (TPA) and mCPP (both via N-dealkylation of the piperazinyl nitrogen mediated by CYP3A4), and a metabolite formed by N-oxidation of the piperazinyl nitrogen. CYP1A2, CYP2D6, and CYP3A4 genotypes all do not seem to predict concentrations of trazodone or mCPP. In any case, there are large interindividual variations in the metabolism of trazodone. In addition, poor metabolizers of dextromethorphan, a CYP2D6 substrate, eliminate mCPP more slowly and have higher concentrations of mCPP than do extensive metabolizers.mCPP is formed from trazodone by CYP3A4 and is metabolized via hydroxylation by CYP2D6 (to a para-hydroxylated metabolite). It may contribute to the pharmacological actions of trazodone.
There is limited but conflicting evidence to support the use of trazodone in the treatment of headaches and migraines in children. Trazodone may be useful in the treatment of fibromyalgia as well as diabetic neuropathy. It may also be useful in the treatment of burning mouth syndrome. A 2004 narrative review claimed that trazodone could be used in the treatment of complex regional pain syndrome. Trazodone may also be effective in the treatment of functional gastrointestinal disorders. It may be effective in the treatment of non-cardiac chest pain as well.Trazodone may be useful in promoting motor recovery after stroke. Veterinary use
Trazodone has been used to reduce anxiety and stress, to improve sleep, and to produce sedation in dogs and cats in veterinary medicine. References
External links

"Trazodone". Drug Information Portal. U.S. National Library of Medicine. "Trazodone hydrochloride". Drug Information Portal. U.S. National Library of Medicine.