A double-blind comparison was made between amitriptyline alone and amitriptyline with added L-triiodothyronine (T3, liothyronine sodium at two dose levels, in cases of depression seen in general practice. Assessments were made initially, and at 3, 7, 10, 14, and 21 days, using Hamilton's Depression Scales and the NIMH Self-Rating Scales. Significant differences in favor of the two regimes with added liothyronine were obtained at 14 days on both scales (P < .01) and on the Self-Rating Scales at ten days (P < .05). Results were better with the higher dose of liothyronine, particularly in females where the difference was significant at three days (P < .05).
Wheatley D. Potentiation of Amitriptyline by Thyroid Hormone. Arch Gen Psychiatry. 1972;26(3):229-233. doi:10.1001/archpsyc.1972.01750210037008