Tiromel T3 Detailed
Thyroid hormone drugs are natural or synthetic preparations
containing tetraiodothyronine (T4, levothyroxine) sodium or
triiodothyronine (T3, liothyronine) sodium or both. T4 and T3 are
produced in the human thyroid gland by the iodination and coupling of
the amino acid tyrosine T4 contains four iodine atoms and is formed by
the coupling of two molecules of diiodotyrosine (DIT). T3 contains
three atoms of iodine and is formed by the coupling of one molecule of
DIT with one molecule of monoiodotyrosine (MIT). Both hormones are
stored in the thyroid colloid as thyroglobulin.
Thyroid hormone
preparations belong to two categories (1) natural hormonal preparations
derived from animal thyroid, and (2) synthetic preparations. Natural
preparations include desiccated thyroid and thyroglobulin. Desiccated
thyroid is derived from domesticated animals that are used for food by
man (either beef or hog thyroid) and thyroglobulin is derived from
thyroid glands of the hog. The United States Pharmacopeia (USP) has
standardized the total iodine content of natural preparations. Thyroid
USP contains not less than (NLT) 0.17 percent and not more than (NMT)
0.23 percent iodine, and thyroglobulin contains not less than (NLT) 0.7
percent of organically bound iodine. Iodine content is only an indirect
indicator of true hormonal biologic activity.