Topical activity of some corticosteroids on different inflammatory responses

Abstract

In recent years, the search for new topical corticosteroids has been generally focused on the potency of action and based on tests which set in evidence the vascular component of inflammation, such as cutaneous vasoconstriction, skin stripping, irritant induced ery thema, etc. (1-4). Since steroid-responsive dermatoses include disorders in which the predominant reaction is either vascular (e.g. acute eczema, contact dermatitis) or cellular (e.g. chronic eczema, dry eczema), we compared the effects of three different corticosteroids on both the vascular and cellular components of inflammation in some common laboratory tests.Betamethasone, a fluorinated corticosteroid, hydrocortisone, a non fluroinated corti costeroid and the hydrocortisone-bendazac ester were studied, the latter being included in the study on account of its unusual spectrum of activity (5). Carrageenin paw edema and cotton pellet granuloma were used as inflammatory responses; the former represents a model in which the vascular component prevails, the latter a model in which cellular proliferation prevails.Long Evans rats of both sexes, weighing 150-180 g, were used. The animals were given a standard diet and water ad libitu m. Betamethasone valerate, hydrocortisone acetate and the hydrocortisone-bendazac ester were used. The carrageenin paw edema was induced according to the method Winter et al. (6). The paw was measured 2 hr after injection of the drugs suspended in carrageenin (0.05 ml of a I % solution). The cotton pellet granuloma test was performed according to the method of Meier et al. (7). Two sterile cotton pellets were symmetrically implanted into the back of each rat. One pellet was soaked with 0.5 ml of an ethanol solution of the products, the other with the solvent alone. Before implantation, the pellets were dried (40'C for 24 hr). Three days later, the animals were sacrificed and the granulomata removed, dried (60'C for 24 hr) and weighed. Since the regression curves were not parallel, the potency ratios for each drug in the carrageenin and cotton pellet tests were calculated on the basis of the minimal effective concentration (MEC).The effects of various concentrations of betamethasone, hydrocortisone and hydro cortisone-bendazac ester on carrageenin paw edema are reported in Figure 1. All drugs