Brands Classes Brand name Synthroid, Levoxyl, Levothroid, Eltroxin, Thyrox, Thyronorm Generic name Levothyroxine Chemical class Levoisomer of thyroxine Therapeutic class Thyroid hormone Avail forms Tablets - Oral 25 mcg, 50 mcg, 75 mcg, 88 mcg, 100 mcg, 112 mcg, 125 mcg, 137 mcg, 150 mcg....