Pharmacokinetic and adrenal interactions of IL-10 and prednisone in healthy volunteers

The pharmacokinetic and adrenal interactions of recombinant human interleukin-10 and prednisolone were examined in this open-label, randomized, four-way crossover study in 12 healthy adult male volunteers. Single doses of IL-10 (8 μg/kg SC), IL-10 with prednisone (15 mg PO), placebo with prednisone, or placebo were administered on four separate occasions with at least 3-week interceding washout periods. Measurements included plasma prednisone, prednisolone and cortisol, unbound prednisolone, and serum IL-10 concentrations. Pharmacokinetic parameters were determined using noncompartmental and model-fitting analysis, while area analysis and an indirect response model were used to assess cortisol dynamics. IL-10 exhibited prolonged serum concentrations owing to dual-absorption processes that were largely unaffected by prednisone. The C(max) values were about 3 ng/mL, while the t(max) occurred at 7 to 9 hours. Prednisolone exhibited rapid systemic kinetics with a C(max) of 235 ng/mL, t(max) at 1.11 hours, and t(1/2) of 2.54 hours with no significant alterations owing to IL-10. Both prednisolone and prednisolone/IL-10 caused marked suppression of cortisol concentrations with similar magnitude and IC₅₀ values; however, IL-10 alone significantly increased the 24-hour AUC of cortisol by 20%. Thus, IL-10 and prednisolone do not interact in disposition or adrenal suppression to a clinically significant degree. (C) 1999 the American College of Clinical Pharmacology.