Verenigbaarheid en keuze crème erythromycine, nystatine en prednisolone

STABILITY OF PREDNISOLONE AND PREDNISOLONE TOPICAL PREPARATIONS ACETATE IN VARIOUS VEHICLES USED IN SEMI-SOLID TOPICAL PREPARATIONS

The effect of the lipophilic vehicles on steroid degradation was only examined with prednisolone, as prednisolone acetate is unlikley to be hydrolysed in this type of vehicle under the conditions studied. The almond oil and beeswax used in this study did not appear to affect the prednisolone stability, which agrees with investigations using two other lipophilic vehicles, namely silicone fluid (3) and petrolatum (6). This could be expected as it has been shown that corticosteroid degradation mainly occurs in aqueous media with low or high pH or containing metal traces (2, 14). The amphiphilic excipients primarily affected the non-esterified compound, whereas prednisolone acetate was either unaltered or only slightly altered. This demonstrates that the ester group on C,, has a protective effect against the degradation process. In Lanettea N, which is a mixture (9+ 1) of cetylstearylalcohol and sodium cetylstearylsulphate, degradation might actually be induced by both constituents. Indeed, two similar substances, i.e. cetanol(7) and sodium laurylsulphate (3, have been reported to affect negatively the stability ofprednisolone and hydrocortisone. Moreover, Lanettea N contains up to 1.4% unspecified inorganic salts, which might also have an effect. Cremophora RH 40, on the other hand, is a polyethoxylated castor oil which contains polyethyleneglycol, ethoxylated glycerin, polyethoxylated glycerylhydroxystearate and polyethoxylated fatty acid esters. The adverse effect of this vehicle on steroid stability might be due to the ethoxyl groups or the polyethyleneglycol. Allen and Das Gupta (8) have shown that this last compound is an unsuitable vehicle for corticosteroid formulations.