Anterior pituitary drugs

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.

Pharmacokinetics

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.

Absorption, distribution, and metabolism

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.

Pharmacodynamics

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.

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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.

Pharmacotherapeutics

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.

Drug interactions

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 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.)