DrugLib.com — Drug Information Portal

Rx drug information, pharmaceutical research, clinical trials, news, and more



Tryptophan-depletion challenge in depressed patients treated with desipramine or fluoxetine: implications for the role of serotonin in the mechanism of antidepressant action.

Author(s): Delgado PL, Miller HL, Salomon RM, Licinio J, Krystal JH, Moreno FA, Heninger GR, Charney DS

Affiliation(s): Department of Psychiatry, West Haven Department of Veterans Affairs Medical Center, Yale University School of Medicine, New Haven, CT, USA.

Publication date & source: 1999-07-15, Biol Psychiatry., 46(2):212-20.

Publication type: Clinical Trial; Randomized Controlled Trial

BACKGROUND: Brain serotonin (5-HT) content is dependent on plasma levels of the essential amino acid, tryptophan (TRP). We have previously reported that rapid TRP depletion more frequently reversed the antidepressant response to monoamine oxidase inhibitors and 5-HT reuptake inhibitors than to desipramine (DMI). This study further investigates the relationship of relapse during TRP depletion to antidepressant type in nonrefractory, depressed patients randomly assigned to treatment with either DMI or fluoxetine (FLU). METHODS: Fifty-five drug-free depressed (DSM-III-R) patients were randomly assigned to antidepressant treatment with either DMI or FLU. All patients were either treatment naive (n = 34) or had previously received successful antidepressant treatment (n = 21). During the treatment phase, 35 patients had therapeutic responses by predetermined criteria (DMI 18/25; FLU 17/23) and 30 of these (15 DMI responders and 15 FLU responders) went on to TRP depletion testing. Patients received two 2-day test sessions involving administration of similar amino acid drinks. One session led to rapid TRP depletion and the other did not. Behavioral ratings [Hamilton Depression Scale (HDRS)] and plasma for TRP levels were obtained prior to, during, and after testing. Relapse was defined as a 50% increase in HDRS with total < or = 17. RESULTS: Total and free TRP decreased 70% to 80% 5 hours after the TRP-free drink. While 8/15 FLU responders relapsed, only 1/15 of the DMI responders relapsed. No patient experienced significant depressive symptoms during control testing. CONCLUSIONS: Rapid depletion of plasma TRP transiently reverses the antidepressant response in many patients on FLU but not DMI. Depressive relapse during TRP depletion appears to be more related to antidepressant type than to patient variables since patients were randomly assigned to the two treatments. Antidepressant response to FLU appears to be more dependent on 5-HT availability than that of DMI, suggesting that antidepressants mediate their therapeutic effects through different mechanisms.

Page last updated: 2006-01-31

-- advertisement -- The American Red Cross
 
Home | About Us | Contact Us | Site usage policy | Privacy policy

All Rights reserved - Copyright DrugLib.com, 2006-2017