Anterior pituitary drugs
The protein hormones produced in the anterior pituitary gland regulate growth, development, and sexual characteristics by stim-ulating the actions of other endocrine glands. Anterior pituitarydrugs include:
§ adrenocorticotropics, which include corticotropin, corticotro-pin repository, corticotropin zinc hydroxide, and cosyntropin
§ somatrem and somatropin, growth hormones
§ gonadotropics, which include chorionic gonadotropin and menotropins
§ thyrotropics, which include thyroid-stimulating hormone, thy-rotropin, and protirelin.
Anterior pituitary drugs aren’t given orally because they’re de-stroyed in the GI tract. Some of these hormones can be adminis-tered topically, but most require injection.
Usually, natural hormones are absorbed, distributed, and metab-olized rapidly. Some analogues, however, are absorbed and me-tabolized more slowly. Anterior pituitary hormone drugs are metabolized at the receptor site and in the liver and kidneys. The hormones are excreted primarily in urine.
Anterior pituitary drugs exert a profound effect on the body’s growth and development. The hypothalamus controls secretions of the pituitary gland. In turn, the pituitary gland secretes hor-mones that regulate secretions or functions of other glands.
The concentration of hormones in the blood helps determine hor-mone production rate. Increased hormone levels inhibit hormone production; decreased levels raise production and secretion.
Anterior pituitary hormone drugs are used for diagnostic and ther-apeutic purposes:
· Corticotropin and cosyntropin are used diagnostically to differ-entiate between primary and secondary failure of the adrenal cortex.
· Corticotropin is also used to treat adrenal insufficiency.
· Somatrem is used to treat growth hormone deficiency.
Anterior pituitary drugs interact with several types of drugs:
§ Administering immunizations to a person receiving cortico-tropin increases the risk of neurologic complications and may re-duce the antibody response.
§ Corticotropin reduces salicylate levels.
§ Enhanced potassium loss may occur when diuretics are taken with corticotropins.
§ Barbiturates, phenytoin, and rifampin increase the metabolism of corticotropin, reducing its effects.
· Estrogen increases the effect of corticotropin.
· Taking estrogens, amphetamines, and lithium with cosyntropin can alter results of adrenal function tests.
· Concurrent use of amphetamines and androgens with somatrem may promote epiphyseal closure (closure of the cartilaginous bone growth plate).
· Concurrent use of somatrem and corticosteroids inhibits the growth-promoting action of somatrem. (See Adverse reactions toanterior pituitary drugs.)