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There is a brief description of the T3/T4 med discussed in the article about Thyroid Hormone replacement.
ARMOUR THYROID ORAL
Pharmacology & Chemistry
The principal pharmacologic effect of exogenous thyroid hormones is to increase the metabolic rate of body tissues. Thyroid hormones are also involved in the regulation of cell growth and differentiation. Although the precise mechanism of action by which thyroid hormones affect metabolism and cellular growth and differentiation is not clearly established, it is known that these physiologic effects are mediated at the cellular level, principally via triiodothyronine; a major portion of triiodothyronine is derived from thyroxine by deiodination in peripheral tissues. Thyroxine is the major component of normal secretions of the thyroid gland and is therefore the principal determinant of normal thyroid function.
Chemistry
In one study of commercially available thyroid preparations, the mean levothyroxine and liothyronine concentrations in each 60 mg of thyroid ranged from 8.8 to 59 mcg and 7.9 to 18 mcg, respectively. Current USP standards specify the measurable amounts of levothyroxine and liothyronine as 38 and 9 mcg, respectively, in each 65 mg of thyroid; however, because of difficulty in measuring the actual hormonal content of thyroid USP, these measurable amounts may be less than the clinical equivalent. Each 60—65 mg of thyroid is approximately clinically equivalent to 100 mcg or less of levothyroxine sodium or to 25 mcg of liothyronine sodium. In guiding dosage adjustment, the clinical equivalent and not the measurable amount should be used.
ARMOUR THYROID ORAL
Pharmacology & Chemistry
The principal pharmacologic effect of exogenous thyroid hormones is to increase the metabolic rate of body tissues. Thyroid hormones are also involved in the regulation of cell growth and differentiation. Although the precise mechanism of action by which thyroid hormones affect metabolism and cellular growth and differentiation is not clearly established, it is known that these physiologic effects are mediated at the cellular level, principally via triiodothyronine; a major portion of triiodothyronine is derived from thyroxine by deiodination in peripheral tissues. Thyroxine is the major component of normal secretions of the thyroid gland and is therefore the principal determinant of normal thyroid function.
Chemistry
In one study of commercially available thyroid preparations, the mean levothyroxine and liothyronine concentrations in each 60 mg of thyroid ranged from 8.8 to 59 mcg and 7.9 to 18 mcg, respectively. Current USP standards specify the measurable amounts of levothyroxine and liothyronine as 38 and 9 mcg, respectively, in each 65 mg of thyroid; however, because of difficulty in measuring the actual hormonal content of thyroid USP, these measurable amounts may be less than the clinical equivalent. Each 60—65 mg of thyroid is approximately clinically equivalent to 100 mcg or less of levothyroxine sodium or to 25 mcg of liothyronine sodium. In guiding dosage adjustment, the clinical equivalent and not the measurable amount should be used.
