Aliment. Pharmacol.Ther. (1992) 6, 351-357. Pharmacokinetics and absolute rectal bioavailability of hydrocortisone acetate in distal co litis i' .,\, O. PETITJEAN", J. L. WENDLING", M. TOD", K. LOUCHAHI", P. NICOLAS", G. PERRET" & A. ASTIER§ "Département de Pharmacotoxicologie, Hôpital Avicenne, 93009 Bobigny Cedex, France, :j:Département de Gastroenterologie, Institut Gustave-Roussy, 94800 Villejuif, France, § Département de Pharmacie, Hôpital Henri-Mondor, 94000 Créteil, France Accepted for publication 10 February 1992 .l "- SUMMARY The hydrocortisone pharmacokinetic profiles of hydrocortisone acetate foam (Proctocort) administered rectally was assessed in healthy volunteers and patients with ulcerative colitis or X-irradiation colitis. Endogenous production of hydrocortisone was suppressed by dexamethasone. Comparison of these data with those obtained after intravenous administration enabled assessment of absolute bioavailability, which was 30.0:t 15.1% in healthy volunteers vs. 16.4:t 14.8% in patients (P = 0.09). Maximal concentrations of hydrocortisone were also decreased in patients, 277:t215 nmoljL vs. 610:t334 nmoljL (P = 0.03). There was a nonsignificant tendency to faster absorption of hydrocortisone in patients vs. healthy volunteers, as the times to peak concentration were, respectively, 2.5 :t 1.2 h vs. 2.8:t 0.8 h (P = 0.64), and the mean absorption times were 1.96:t 1.45 h Ys.2.54:t 1.62 h (P = 0.46). Thus, rectal inflammation resulted in a lower absorption of "'" Co Correspondence to: Dr M. Tod, Département de Pharmacotoxicologie, Hôpital Avicenne, 125 route de Stalingrad, 93009 Bobigny Cedex, France. 351 23 BAP 6