8-[3-[4-(3-chlorophenyl)piperazin-1-yl]propyl]-6,8,9-triazabicyclo[4.3.0]nona-2,4,9-trien-7-one

Absorption
Well absorbed after administration. Tmax is 1 h on an empty stomach and 2 h with food.

Metabolism
Metabolized to an active metabolite, m-chlorophenyl-piperazine, by CYP3A4.

Elimination
Undergoes biphasic elimination with an initial phase (t½ , 3 to 6 h) followed by a slower phase (t½ , 5 to 9 h).

Alcohol, barbiturates, CNS depressants
CNS depressant effects may be additive.

Carbamazepine
Plasma concentrations of trazodone and its active metabolite may be decreased, producing a decrease in therapeutic effect.

CYP3A4 inhibitors (eg, indinavir, itraconazole, ketoconazole, nefazodone)
May increase trazodone levels, increasing adverse reactions.

Digoxin, hydantoins
Serum levels may be elevated by trazodone, increasing the pharmacologic and adverse reactions.

Hypotensive agents
May cause additive hypotensive effects.

MAOIs
It is unknown whether interactions may take place. Initiate trazodone therapy cautiously if patient is currently taking, or has recently stopped taking, MAOIs.

Phenothiazines, protease inhibitors
Elevated trazodone serum concentrations have occurred, increasing the pharmacologic and toxic effects.

Ritonavir
Increased C max , AUC, and elimination t ½ , and decreased Cl of trazodone.

SSRIs
A serotonin syndrome, including altered consciousness, increased muscle tone, irritability, myoclonus, and shivering may occur.

Warfarin
Reports of increased and decreased PT.