Cushing's syndrome has been reported in infants and adults as a result of prolonged use of topical clobetasol propionate formulations. The following additional local adverse reactions have been reported with topical corticosteroids, and they may occur more frequently with the use of occlusive dressings and higher potency corticosteroids. These reactions are listed in an approximately decreasing order of occurrence: dryness, acneiform eruptions, hypopigmentation, perioral dermatitis, allergic contact dermatitis, secondary infection, irritation, striae, and miliaria.
Systemic absorption of topical corticosteroids has produced reversible hypothalamic-pituitary-adrenal (HPA) suppression and/or manifestations of Cushing's syndrome in some patients. Clobetasol propionate has been shown to suppress the HPA axis at doses as low as 2 g/day. Conditions which increase systemic absorption include application of high-potency corticosteroids, use over large surface areas, prolonged use, use in areas where the epidermal barrier is disrupted (., skin abrasion), use in pediatric patients, use in patients with hepatic disease, and the use of an occlusive dressing. Clobetasol propionate preparations should not be used with occlusive dressings. Patients receiving large doses of a potent topical corticosteroid like clobetasol should be evaluated periodically for evidence of HPA axis suppression and manifestations of Cushing's syndrome. If these effects are noted, an attempt should be made to withdraw the drug, to reduce the frequency of application, or to substitute a less potent corticosteroid. Recovery of HPA axis function is generally prompt and complete upon discontinuation. Infrequently, signs and symptoms of withdrawal may occur, requiring supplemental systemic corticosteroids. It is recommended that the administration of clobetasol creams, ointments, gels, or topical solutions be limited to no more than 14 days duration, in order to limit the risk of systemic effects. Clobetasol propionate emollient creams may be administered for up to 4 weeks duration if applied to no more than 5—10% of body surface area. The total weekly dose limit of 50 g or 50 mL of a % preparation should not be exceeded for any clobetasol preparation.
Steroid isolation , depending on context, is the isolation of chemical matter required for chemical structure elucidation, derivitzation or degradation chemistry, biological testing, and other research needs (generally milligrams to grams, but often more  or the isolation of "analytical quantities" of the substance of interest (where the focus is on identifying and quantifying the substance (for example, in biological tissue or fluid). The amount isolated depends on the analytical method, but is generally less than one microgram.  [ page needed ] The methods of isolation to achieve the two scales of product are distinct, but include extraction , precipitation, adsorption , chromatography , and crystallization . In both cases, the isolated substance is purified to chemical homogeneity; combined separation and analytical methods, such as LC-MS , are chosen to be "orthogonal"—achieving their separations based on distinct modes of interaction between substance and isolating matrix—to detect a single species in the pure sample. Structure determination refers to the methods to determine the chemical structure of an isolated pure steroid, using an evolving array of chemical and physical methods which have included NMR and small-molecule crystallography .  :10–19 Methods of analysis overlap both of the above areas, emphasizing analytical methods to determining if a steroid is present in a mixture and determining its quantity.