Conclusion:
Trazodone is an old friend in psychopharmacology, now seen as a multifunctional drug with pharmacologic actions at low doses making
it a hypnotic and additional multifunctional pharmacologic actions at high doses making it an antidepressant. The IR formulation of trazodone
is preferred for hypnotic use, whereas the new controlled release formulation of trazodone XR may be preferred for antidepressant use. Trazodone XR should theoretically allow adequate dose escalation to administer high doses for antidepressant action while avoiding sedation of the immediate release formulation. As an antidepressant, trazodone should be as effective as SSRIs/SNRIs, yet have a low incidence of anxiety, insomnia and sexual dysfunction, the properties expected for a multifunctional SARI.
http://www.cnsspectrums.com/UserDocs/ArticleImages/176/1009CNS_Stahl.pdf