Phenylalanine is an essential amino acid that converts to tyrosine. It follows the catecholamine pathway and is a precursor to thyroid hormone. Phenylalanine--Tyrosine--Norepinephrine --Epinephrine. It should not be used with MAO inhibitors or tricyclic antidepressants, or those who have PKU or hypertension.
vegetarian capsule, L-leucine