Anti-allergic, corticoids

The effect on the potency of steroids of adding the extra double in ring A has resulted in the incorporation of this structural feamre in the majority of anti-inflammatory and anti-allergic corticoids. This observation also holds true for inclusion of halogen atoms and most frequently fluorine in the structure. Fluorine at C9 and/or Cg is thus found in the majority of corticoids. The very versatile sequence for introducing fluorine discussed in Chapter 5 (Scheme 5.31) was most likely first developed and subsequently applied in the corticoid series. 

Corticosteroids do not heal illnesses, but they are widely used in various conditions when it is necessary to utilize their anti-inflammatory, immunosuppressant, and mineralo-corticoid properties. In addition, they are used in replacement therapy for patients who have adrenal insufficiency. Corticosteroids can be used in vital situations for asthma, severe allergic reactions, and transplant rejections. They are effective in noninfectious granulomatous diseases such as sarcoidosis, collagen vascular disease, rheumatoid arthritis, and leukemia. Steroids are used as lotions, ointments, etc. in treating a number of dermatological and ophthalmologic diseases. 

The introduction of a 16a-hydroxy group into 6a,9-difluoro-prednisolone led to a compound (fluocinolone) with the anticipated favorable biological spectrum, namely high anti-inflammatory activity (35-fold that of hydrocortisone, seven-fold that of triamcinolone) and - in contrast to the C-16 unsubstituted compound - no retention of sodium. The corresponding 16,17-acetonide (fluocinolone acetonide) exhibited 100-fold the anti-inflammatory activity of hydrocortisone, with no sodium retention. In clinical trials, 6a,9-difluoro-16a-hydroxyprednisolone was found to be a potent suppressor of inflammatory conditions such as rheumatoid arthritis, as well as allergic conditions such as asthma, whilst its acetonide proved to be highly effective as topical corticoid. 

Vasovagal reaction (bradycardia, pallor, and loss of consciousness) is related to pain rather than contrast medium. The lower limbs are elevated atropine is sometimes useful. Mild allergic accident (itching, urticaria) can be treated by corticoids and an anti-histaminic medication. 

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