Collagen fibril formation in the presence of dexamethasone disodium phosphate.

Dexamethasone disodium phosphate was found to inhibit in vitro fibrillogenesis in a buffered collagen solution that otherwise formed in vivo like fibrils. A nonlinear relationship was observed between the steroid salt concentration and the kinetic parameter half transition time. Full fibril inhibition occurred at dexamethasone phosphate concentrations above 15 mM. At lower concentrations, sample buffers that also contained inorganic phosphate were not different from the control in activation energy of 224.3 +/- 29.3 kJ/mol (53.6 +/- 7.0 kcal/mol). The idea is advanced that the soluble steroid salt associates directly to the collagen and prevents the formation of lateral, hydrophobic interactions between adjacent collagen aggregates.