Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Trazodone is indicated for treatment of depression characterized by a prominent and persistent dysphoric mood that interferes with daily function.
Trazodone is administered in oral doses of 150 to 400 mg/day in divided doses to yield blood levels of 650 to1,500 ng/mL that correlate with response to the drug.
Within the therapeutic range, trazodone is 93% protein bound. It exhibits a volume of distribution of 1.0 L/kg and an elimination half-life of 6 hours. Oral bioavailability ranges from 60% to 90%.
Priapism and hypotension are side effects that occur at therapeutic doses of the drug.
There are no known major drug interactions that affect the pharmacology of trazodone.
Toxicity is characterized by respiratory arrest, seizure, and electrocardiogram changes typical of atrioventricular conduction block. There is no specific antidote to trazodone overdose; treatment is symptomatic and supportive.
Monitoring for optimal therapeutic concentrations
Monitoring patient compliance
Most individuals display optimal response to trazodone when serum levels are 650 to 1,500 ng/mL. Some individuals may respond well outside of this range, or may display toxicity within the therapeutic range, thus interpretation should include clinical evaluation. Toxic levels have not been well established. Theraputic ranges are based on samples drawn at trough (ie, immediately before the next dose.)
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
No significant cautionary statements
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
Therapeutic concentration: 650-1,500 ng/mL
Clinical References Provides recommendations for further in-depth reading of a clinical nature
1. Hiemke C, Baumann P, Bergemann N, et al: AGNP Consensus Guidelines for Therapeutic Drug Monitoring in Psychiatry: Update 2011. Pharmacopsychiatry 2011 Sept;44(6):195-235
2. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. Edited by CA Burtis, ER Ashwood, DE Bruns. Fifth edition. Saunders, 2011