Pharmacokinetics of budesonide enema in patients with distal ulcerative colitis or proctitis.

Pharmacokinetic data obtained after one dose of a 2-mg budesonide enema were compared with data obtained after the last dose of four weeks of daily treatment in 24 patients with active distal ulcerative colitis or proctitis. This open multicentre study involved 28 eligible patients. Sigmoidoscopy and biopsy scores improved significantly (P < 0.002) during the four-week treatment period. Maximal plasma concentration (Cmax) of budesonide was 2.1 nmol/L 1.3 h after the first dose and 2.5 nmol/L 1.2 h after the last dose; the difference was not significant. The area under the curve (AUC) of plasma concentration vs. time was after the first dose 9.7 nmol h/L and after the last dose 11.6 nmol h/L (P < 0.03). The small increase in AUC may be attributed to improved absorption. During the last dose interval, minimal plasma concentration was below the limit of quantitation in most subjects. The Cmax and AUC of budesonide increased slightly after four weeks of treatment, but budesonide did not accumulate. Mean morning plasma cortisol values did not change significantly during treatment (P = 0.083), although a small change in cortisol levels between the first visit (pre-treatment) and last visit was positively correlated to the Cmax of budesonide measured at the last visit (P = 0.012).