Structural activities of the anti-inflammatory steroids and their relationship to osseous tissue

One hundred eighty young New Zealand White rabbits were treated for twenty days with graded doses of natural and synthetic anti-inflammatory steroids. The following drugs were used subcutaneously: Cortisol, corticosterone, paramethasone acetate, flumethasone, fluscinolone acetonide, triamcinolone, and triamcinolone acetonide. On days two and sixteen of the experiment the rabbits were given an I. M. injection of tetracycline to label the bones at sites of formation. Three skeletal sites, the proximal tibia, femoral diaphysis and fourth lumbar-vertebral body were sampled. A number of growth parameters were studied in each site and potency ratios, fiducial limits and lambda values were determined for the various drugs employed. Soft tissue changes in spleen, thymus, adrenal and body weight were also evaluated. In general soft tissue effects paralleled those in the skeleton but most closely resembled the pattern of response in the tibia. The femoral cortex was the most sensitive with the lumbar vertebral body intermediate and tibia the least sensitive site in response to corticosteroids. Of the seven hormones studied flumethasone proved to be the most potent. In decreasing order of potency in the tibia are? paramethasone acetate, Cortisol, and corticosterone. Flumethasone, paramethasone acetate, triamcinolone, Cortisol and corticosterone caused graded responses in the vertebral body parameters. All of the hormones reduced accretion rates in the three envelopes" of the femoral cortex. Endochondral growth in the proximal tibia was best correlated with primary spongiosa thickness, osteoblasts of the primary spongiosa, and body weight change