NP Thyroid 90

Generic name:levothyroxine, liothyronine
Dosage form: tablet
Drug class:Thyroid drugs

Medically reviewed by Drugs.com. Last updated on Oct 22, 2021.

Disclaimer: This drug has not been found by FDA to be safe and effective, and this labeling has not been approved by FDA. For further information about unapproved drugs, click here.

NP Thyroid (thyroid tablets, USP) for oral use is a natural preparation derived from porcine thyroid glands. They contain both tetraiodothyronine sodium (T4 levothyroxine) and triiodothyronine sodium (T3 liothyronine) providing 38 mcg levothyroxine (T4) and 9 mcg liothyronine (T3) per grain of thyroid. The inactive ingredients are calcium stearate, dextrose monohydrate, maltodextrin and mineral oil.

CLINICAL PHARMACOLOGY: The steps in the synthesis of the thyroid hormones are controlled by thyrotropin (Thyroid Stimulating Hormone, TSH) secreted by the anterior pituitary. This hormone’s secretion is in turn controlled by a feedback mechanism effected by the thyroid hormones themselves and by thyrotropin releasing hormone (TRH), a tripeptide of hypothalamic origin. Endogenous thyroid hormone
secretion is suppressed when exogenous thyroid hormones are administered to euthyroid individuals in excess of the normal gland’s secretion. The mechanisms by which thyroid hormones exert their physiologic action are not well understood. These hormones enhance oxygen consumption by most tissues of the body, increase the basal metabolic rate, and the metabolism of carbohydrates, lipids, and proteins. Thus, they exert a profound influence on every organ system in the body and are of particular importance in the development of the central nervous system. The normal thyroid gland contains
approximately 200 mcg of levothyroxine (T4) per gram of gland, and 15 mcg of liodothyronine (T3) per gram. The ratio of these two hormones in the circulation does not represent the ratio in the thyroid gland, since about 80 percent of peripheral triiodothyronine comes from monodeiodination of levothyroxine. Peripheral monodeiodination of levothyroxine at the 5 position (inner ring) also results in the formation of reverse triiodothyronine (T3), which is calorigenically inactive. Triiodothyronine (T3) levels are low in the fetus and newborn, in old a.