PHARMACOLOGY OF INHALED GLUCOCORTICOIDS

Abstract

The inhaled glucocorticoids are the most effective drugs currently available for the long-term control of persistent asthma and offer the broadest array of anti-inflammatory activity. 7 The inhaled glucocorticoids were developed to provide the beneficial effects of glucocorticoids without the unwanted adverse effects. To achieve improved local or topical selectivity, physicochemical modifications of the basic steroid structure were made that result in both enhanced topical potency and diminished systemic activity. The structural changes have also produced differences in pharmacokinetics and potency among the various products. 7,14,20,37 As a result, the recently published National Asthma Education and Prevention Program (NAEPP) guidelines for asthma treatment provide a dosage table of approximately comparative clinical dosages for the available inhaled glucocorticoids (Table 1). 44 This table assumes that, aside from potency differences, only minimal differences in topical selectivity exist among products. Since the NAEPP guidelines were published, a number of comparative clinical trials have confirmed the existence of clinically significant differences in potency among the inhaled glucocorticoids. 37,48 There is some suggestion that significant differences in topical selectivity may also exist. This article evaluates how the clinical pharmacologic differences among the inhaled glucocorticoid products might translate into significant differences in their clinical effectiveness. The clinical trials that concurrently evaluate safety and efficacy are reviewed to confirm clinically important differences among products.