Toxicity - Synthetic Corticosteroids

Toxicity

The benefits obtained from glucocorticoids vary considerably. Use of these drugs must be carefully weighed in each patient against their widespread effects on every part of the organism. The major undesirable effects of glucocorticoids are the result of their hor-monal actions, which lead to the clinical picture of iatrogenic Cushing’s syndrome (see later in text).When glucocorticoids are used for short periods (< 2 weeks), it is unusual to see serious adverse effects even with moderately large doses. However, insomnia, behavioral changes (primarily hypoma-nia), and acute peptic ulcers are occasionally observed even after only a few days of treatment. Acute pancreatitis is a rare but seri-ous acute adverse effect of high-dose glucocorticoids.

A. Metabolic Effects

Most patients who are given daily doses of 100 mg of hydrocorti-sone or more (or the equivalent amount of synthetic steroid) for longer than 2 weeks undergo a series of changes that have been termed iatrogenic Cushing’s syndrome. The rate of development is a function of the dosage and the genetic background of the patient. In the face, rounding, puffiness, fat deposition, and plethora usu-ally appear (moon facies). Similarly, fat tends to be redistributed from the extremities to the trunk, the back of the neck, and the supraclavicular fossae. There is an increased growth of fine hair over the face, thighs and trunk. Steroid-induced punctate acne may appear, and insomnia and increased appetite are noted. In the treat-ment of dangerous or disabling disorders, these changes may not require cessation of therapy. However, the underlying metabolic changes accompanying them can be very serious by the time they become obvious. The continuing breakdown of protein and diver-sion of amino acids to glucose production increase the need for insulin and over time result in weight gain; visceral fat deposition; myopathy and muscle wasting; thinning of the skin, with striae and bruising; hyperglycemia; and eventually osteoporosis, diabetes, and aseptic necrosis of the hip. Wound healing is also impaired under these circumstances. When diabetes occurs, it is treated with diet and insulin. These patients are often resistant to insulin but rarely develop ketoacidosis. In general, patients treated with corticoster-oids should be on high-protein and potassium-enriched diets.

B. Other Complications

Other serious adverse effects of glucocorticoids include peptic ulcers and their consequences. The clinical findings associated with certain disorders, particularly bacterial and mycotic infections, may be masked by the corticosteroids, and patients must be carefully monitored to avoid serious mishap when large doses are used. Severe myopathy is more frequent in patients treated with long-acting glucocorticoids. The administration of such compounds has been associated with nausea, dizziness, and weight loss in some patients. It is treated by changing drugs, reducing dosage, and increasing potassium and protein intake.

Hypomania or acute psychosis may occur, particularly in patients receiving very large doses of corticosteroids. Long-term therapy with intermediate- and long-acting steroids is associated with depression and the development of posterior subcapsular cataracts. Psychiatric follow-up and periodic slit-lamp examina-tion is indicated in such patients. Increased intraocular pressure is common, and glaucoma may be induced. Benign intracranialhypertension also occurs. In dosages of 45 mg/m²/d or more of hydrocortisone or its equivalent, growth retardation occurs in children. Medium-, intermediate-, and long-acting glucocorticoids have greater growth-suppressing potency than the natural steroid at equivalent doses.

When given in larger than physiologic amounts, steroids such as cortisone and hydrocortisone, which have mineralocorticoid effects in addition to glucocorticoid effects, cause some sodium and fluid retention and loss of potassium. In patients with normal cardiovas-cular and renal function, this leads to a hypokalemic, hypochloremic alkalosis and eventually to a rise in blood pressure. In patients with hypoproteinemia, renal disease, or liver disease, edema may also occur. In patients with heart disease, even small degrees of sodium retention may lead to heart failure. These effects can be minimized by using synthetic non-salt-retaining steroids, sodium restriction, and judicious amounts of potassium supplements.

C. Adrenal Suppression

When corticosteroids are administered for more than 2 weeks, adrenal suppression may occur. If treatment extends over weeks to months, the patient should be given appropriate supplementary therapy at times of minor stress (two-fold dosage increases for 24–48 hours) or severe stress (up to ten-fold dosage increases for 48–72 hours) such as accidental trauma or major surgery. If corti-costeroid dosage is to be reduced, it should be tapered slowly. If therapy is to be stopped, the reduction process should be quite slow when the dose reaches replacement levels. It may take 2–12 months for the hypothalamic-pituitary-adrenal axis to function acceptably, and cortisol levels may not return to normal for another 6–9 months. The glucocorticoid-induced suppression is not a pituitary problem, and treatment with ACTH does not reduce the time required for the return of normal function.

If the dosage is reduced too rapidly in patients receiving gluco-corticoids for a certain disorder, the symptoms of the disorder may reappear or increase in intensity. However, patients without an underlying disorder (eg, patients cured surgically of Cushing’s disease) also develop symptoms with rapid reductions in cortico-steroid levels. These symptoms include anorexia, nausea or vomit-ing, weight loss, lethargy, headache, fever, joint or muscle pain, and postural hypotension. Although many of these symptoms may reflect true glucocorticoid deficiency, they may also occur in the presence of normal or even elevated plasma cortisol levels, sug-gesting glucocorticoid dependence.