McKenna's Pharmacology for Nursing, 2e

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C H A P T E R 3 6 Adrenocortical agents

Hypothalamus

Exogenous corticosteroids

CRH

Block CRH and ACTH release

Inhibitory

HPA

FIGURE 36.1  A. Normal controls of adrenal gland. The hypothalamus releases corticotropin-releasing hormone (CRH), which causes release of corticotropin (ACTH) from the anterior pituitary. ACTH stimulates the adrenal cortex to produce and release corticosteroids. Increasing levels of corticosteroids inhibit the release of CRH and ACTH. B. Exogenous corticosteroids act to inhibit CRH and ACTH release; the adrenal cortex is no longer stimulated and atrophies. Sudden stopping of steroids results in a crisis of adrenal hypofunction until hypothalamic–pituitary axis (HPA) controls stimulate the adrenal gland again.

Anterior pituitary

No stimulation to adrenal glands

ACTH

A

B

Adrenal cortex

Inhibitory

Gland atrophies and does not produce corticosteroids

Adrenocortical steroids

ADRENOCORTICAL AGENTS There are three types of corticosteroids: androgens (discussed in Chapter 41), glucocorticoids and mineralo- corticoids. Not all adrenocortical agents are classified as only glucocorticoids or mineralocorticoids. Hydrocortis­ one, cortisone and prednisone also have glucocorticoid and some mineralocorticoid activity and affect potas- sium, sodium and water levels in the body when present in high levels (Table 36.2). Box 36.2 discusses their use in different age groups. Figure 36.2 displays the sites of action of the glucocorticoids and the mineralocorticoids. G lucocorticoids Glucocorticoids (Table 36.3) are so named because they stimulate an increase in glucose levels for energy. They also increase the rate of protein breakdown and decrease

the rate of protein formation from amino acids, another way of preserving energy. Glucocorticoids also cause lipogenesis, or the formation and storage of fat in the body. This stored fat will then be available to be broken down for energy when needed. Several glucocorticoids are available for phar- macological use. They differ mainly by route of administration and duration of action. Glucocorticoids include beclomethasone ( Beconase, Qvar ), betameth- asone ( Celestone , Diprosone and others), budesonide ( Entocort , Pulmicort , Rhinocort , Symbicort and others), cortisone ( Cortate ), dexamethasone ( Dexmethsone and others), hydrocortisone ( Sigmacort, Solu-Cortef , and others), methylprednisolone ( Advantan , Depo-Medrol , Depo-Nisolone ), prednisolone ( Panafcortelone , Predsol , Redipred and others), prednisone ( Lodotra , Panafcort , Sone ) and triamcinolone ( Aristocort , Kenacomb , Tri- cortone and others).

■■ TABLE 36.2 Selected corticosteroids: equivalent strength, glucocorticoid and mineralocorticoid effects and duration of effects Drug Equivalent dose (mg) Glucocorticoid effects Mineralocorticoid effects Duration of effects (hours)

Short-acting corticosteroids cortisone

25 20

+ +

++++ ++++

8–12 8–12

hydrocortisone

Intermediate-acting corticosteroids prednisone  5

++++ ++++

++ ++ — —

18–36 18–36 18–36 18–36

prednisolone triamcinolone

 5  4  4

+++++ +++++

methylprednisolone

Long-acting corticosteroids dexamethasone

0.75 0.75

+++++++++ +++++++++

— —

36–54 35–54

betamethasone