Preliminary randomized double-blind placebo-controlled trial of tryptophan combined with fluoxetine to treat major depressive disorder: antidepressant and hypnotic effects.
OBJECTIVE
Because the initial phase of treatment of depression with a selective serotonin reuptake inhibitor is often complicated by a delayed onset of action of the antidepressant or severe insomnia or both, we investigated whether tryptophan, an amino acid with both antidepressant-augmenting and hypnotic effects, would benefit patients with depression at the beginning of treatment with fluoxetine.


DESIGN
Randomized, double-blind, placebo-controlled trial.


PATIENTS
Thirty individuals with major depressive disorder.


INTERVENTIONS
Treatment over 8 weeks with 20 mg of fluoxetine per day and either tryptophan (2 to 4 g per day) or placebo.


OUTCOME MEASURES
Mood was assessed using the 29-item Hamilton Depression Rating Scale (HDRS-29) and the Beck Depression Inventory (BDI). Laboratory sleep studies were done at baseline and after 4 and 8 weeks of treatment using standard procedures.


RESULTS
During the first week of treatment, there was a significantly greater decrease in HDRS-29 depression scores, and a similar trend in BDI scores, in the tryptophan/fluoxetine group than in the placebo/fluoxetine group. No significant differences were noted at later time points. With respect to sleep measures, there was a significant group-by-time interaction for slow-wave sleep at week 4. Further analysis revealed a significant decrease in slow-wave sleep after 4 weeks of treatment in the placebo/fluoxetine group, but not in the tryptophan/fluoxetine group. No cases of serotonin syndrome occurred, and the combination was well tolerated, although the 4 g per day dosage of tryptophan produced daytime drowsiness.


CONCLUSIONS
Combining 20 mg of fluoxetine with 2 g of tryptophan daily at the outset of treatment for major depressive disorder appears to be a safe protocol that may have both a rapid antidepressant effect and a protective effect on slow-wave sleep. Further large-scale studies are needed to confirm these initial findings.