Why hydrocortisone or hydrocortisone acetate in a cream?

P class = "P1" > The general rule is that the esters of corticosteroids are a better form for dermal application of the cortico-alcohol. P class = "P1" > Here are some values for hydrocortisone and ester derivatives: P = permeabilieitscoefficient by isolated skin and PC the distribution coefficient between ether and water, which is a measure of lipoophilism.   P class = "P1" >                                                             P (CM/h)               PC P class = "P1" > span style = "line-height: 1.6 em;" > hydrocortisone                                     1.6 x 10 -4           span style = "line-height: 1.6 em;" >   1.4   P class = "P1" > hydrocortisone-21-acetate                 1.7 x 10-3             27   P class = "P1" > hydrocortisone-21-propionate             9.8   x   10-3         95   P class = "P1" > hydrocortisone-21-butyrate                 4.3 x 10-2           300   P class = "P1" > You see that the strongest derivative is the butyrate ester, which is found in Locoid Crelo.   P class = "P1" > I do not exclude that provided that a special formulation of the excipient also hydrocortisone is absorbed. After all, the cutaneous absorption is a complex mechanism in which many parameters play a role.   P class = "P1" > but generally, hydrocortisone is reserved for oral intake (see TMF).