Glucocorticoids can cause sodium absorption from the kidney that result in
water retention, potassium loss, and increased blood pressure. Cortisol, the pri-
mary glucocorticoid, has anti-inflammatory, anti-allergic, and antistress effects.
Glucocorticoid therapy is used in trauma, surgery, infections, emotional upsets,
and anxiety. Most glucocorticoid drugs are synthetically produced and are admin-
istered orally, IM, IV, topically (see Chapter 20), intranasally (see Chapter 14),
and as aerosol inhalers (see Chapter 14).
Glucocorticoid drugs include beclomethasone dipropionate (Vanceril), beta-
methasone (Celestone), cortisone acetate (Cortone Acetate), dexamethasone
(Decadron), fludrocortisone acetate (Florinef Acetate), hydrocortisone
(Hydrocortone), methylprednisoline (Medrol, Solu-Medrol, Depo-Medrol),
prednisolone, and prednisone. The adrenal medulla synthesizes, stores, and
releases epinephrine and norepinephrine. Hypersecretion causes prolonged or
continual sympathetic nervous system responses. A lack of secretion from the
adrenal medulla has no significant effects.
DRUGS AND THE THYROID GLAND
The thyroid gland secretes two hormones that regulate protein synthesis, enzyme
activity, and stimulate mitochondrial oxidation. These are thyroxine (T4) and tri-
iodothyronine (T3). The thyroid gland secretes 20% of the circulating T3. The
remaining 80% comes from degradation of T4 hormone. Approximately 40% of
T4 is degraded and becomes T3.
T3 and T4 are carried in the blood by thyroxine-binding globulin (TBG) and
albumin, which protects the hormones from being degraded. T3 is more potent than
T4. Only unbound free T3 and T4 are active and produce a hormonal response.
A decreased amount of T3 and T4 is produced in a condition called hypothy-
roidism. This is caused by a disorder of the thyroid gland or a secondary lack of
TSH secretion. Hyperthyroidism is an increase in circulatory T4 and T3 caused
by an overactive thyroid gland or an excessive output of thyroid hormones.
Hypothyroidism
Primary hypothyroidism is characterized by a decrease in T4 and an increase in
TSH levels. Primary hypothyroidism is caused by acute or chronic inflammation
of the thyroid gland, radioiodine therapy, excess intake of antithyroid drugs,
and surgery.
Myexedema is severe hypothyroidism characteristic by lethargy, apathy,
memory impairment, emotional changes, slow speech, deep coarse voice, edema
CHAPTER 21 Endocrine Medications^389