Corticosteroids

Corticosteroids - The commonly used injectable corticosteroids are synthetic analogues of the adrenal glucocorticoid hormone Cortisol (hydrocortisone), which is secreted by the innermost layer (zona reticularis) of the adrenal cortex. Cortisol has many important actions, including effects on protein and glucose metabolism, but it also has anti-inflammatory activity, which is mediated by effects on polymorph and macrophage migration and suppression of the immunological response of lymphocytes2 6 , 2 7 , 1 9 7. When they were first administered systemically in the 1940s steroid drugs were hailed as the new 'universal panacea', but it soon became apparent that major side-effects greatly limited their systemic use2 8 . In 1951, Hollander, in the USA, reported the first use of local hydrocortisone injections for arthritic joints2'. Virtually insoluble steroid suspensions are used because intraarticular soluble steroids will rapidly clear into the systemic circulation.

The suspensions work by minute quantities of the active drug dissolving off the surface of the crystals when in contact with the inflamed tissue28. In joints, the steroid is taken up by the synovial cells before being gradually absorbed into the blood and cleared1 , 3 1 , 2 6 1 , 2 6 2. Corticosteroids exert their many effects on the cells involved in the immune and inflammatory responses primarily by modulating the transcription of a large number of genes. They act directly on nuclear steroid receptors to control the rate of synthesis of mRNA3 2 . However, they also influence the mechanisms by which proteins are synthesized, and thereby affect the production of a wide range of proinflammatory mediators including cytokines" and other important
enzymes.