Thyroid hormone, synthetic T3
Synthetic form of triiodothyronine (T3), increases metabolic rate and enhances neurotransmitter sensitivity, potentially accelerating antidepressant effects
Hypothyroidism
Augmentation in treatment-resistant depression
Oral tablets, injectable formulations (rarely used)
Start at 25 mcg p.o. daily; titrate as clinically indicated, typically 25–50 mcg/day for augmentation
25–50 mcg/day for augmentation
Rapid onset of action; half-life approximately 1–2 days; metabolized peripherally
Palpitations, anxiety, tremor, sweating, insomnia
Cardiac arrhythmias, exacerbation of underlying cardiac disease
Monitor thyroid function tests including TSH, free T3, and free T4 every 6–12 weeks when initiating or adjusting dose
None
Use cautiously in elderly patients due to increased risk of cardiac adverse effects; careful monitoring is essential in those with cardiovascular disease or arrhythmias.