In a trial lasting four weeks patients responded equally well to imipramine (150 mg daily) or to L-tryptophan (9 gm daily). Patients who received a small dose of L-triiodothyronine (T3, liothyronine sodium (25μg daily for the first two weeks of treatment) in addition to imipramine showed a significantly better therapeutic response than patients who received either imipramine or tryptophan alone. Liothyronine did not enhance the therapeutic response to L-tryptophan. None of the treatments tested seemed to benefit any particular symptom of depression differenntially. In particular, L-tryptophan had no specific effect on the sleep deficit of the syndrome. Liothyronine appeared to diminish the side effects of both imipramine and L-tryptophan in both men and women.
Coppen A, Whybrow PC, Noguera R, Maggs R, Prange AJ. The Comparative Antidepressant Value of L-Tryptophan and Imipramine With and Without Attempted Potentiation by Liothyronine. Arch Gen Psychiatry. 1972;26(3):234-241. doi:10.1001/archpsyc.1972.01750210042009