Corticosteroids, specific agents

Starting doses > 100 meg twice/day for adults and adolescents and 50 meg twice daily for children 4 to 11 years of age may be considered for patients with poorer asthma control or those who have previously required doses of inhaled corticosteroids that are in the higher range for that specific agent. ... 

These compounds vary in their specific mechanism of action and often have different effects on the individual patients. Thus, they are generally used in combinations, eg, corticosteroids with an alkylating agent, or an antimetaboUte with a plant alkaloid in a rotating schedule. 

Topical corticosteroids (Table 16-1) may halt synthesis and mitosis of DNA in epidermal cells and appear to inhibit phospholipase A, lowering the amounts of arachidonic acid, prostaglandins, and leukotrienes in the skin. These effects, coupled with local vasoconstriction, reduce erythema, pruritus, and scaling. As antipsoriatic agents, they are best used adjunc-tively with a product that specifically functions to normalize epidermal hyperproliferation. 

Achievement of efficacy by any therapeutic regimen requires days to weeks. Initial dramatic response may be achieved with some agents such as corticosteroids. However, sustained benefit with pharmacologically specific antipsoriatic therapy may require 2 to 8 weeks or longer for clinically meaningful response. 

Mechanism of Action Clioquinol is a broad-spectrum antibacterial agent but the mechanism of action is unknown. Hydrocortisone is a corticosteroid that diffuses across cell membranes, forms complexes with specific receptors and further binds to DNA and stimulates transcription of mRNA (messenger RNA) and subsequent protein synthesis of various enzymes thought to be ultimately responsible for the anti-inflammatory effects of corticosteroids applied topically to the skin Therapeutic Effect Alters membrane function and produces antibacterial activity Pharmacokinetics Clioquinol may be absorbed through the skin in sufficient amounts. 

The synthetic analogs of cortisol are useful in the treatment of a diverse group of diseases unrelated to any known disturbance of adrenal function (Table 39-2). The usefulness of corticosteroids in these disorders is a function of their ability to suppress inflammatory and immune responses and to alter leukocyte function, as previously described and as described in Chapter 55. These agents are useful in disorders in which host response is the cause of the major manifestations of the disease. In instances in which the inflammatory or immune response is important in controlling the pathologic process, therapy with corticosteroids may be dangerous but justified to prevent irreparable damage from an inflammatory response—if used in conjunction with specific therapy for the disease process. 

Corticosteroids potentially used in food-producing animals include a variety of compounds such as cortisone, cortisol, prednisone, prednisolone, methylpredniso-lone, betamethasone, dexamethasone, flumethasone, fluoroprednisolone, isoflu-predone, and triamcinolone. Corticosteroid administration to feedlots as growth-promoting agents has been recently introduced illicitly in animal production because of their ability to promote water retention in the body. This use has been strongly enhanced for commercial reasons, in order to produce meat more appealing to consumers, due to the juicy and lean look. It is therefore crucial to rely on accurate, sensitive and specific analytical methods to measure residues in biological samples. 

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