British Journal of Anaesthesia, 1993, Vol. 71, No. 6 827-834
© 1993 The Board of Management and Trustees of the British Journal of Anaesthesia
research-article |
INFLUENCE OF CROHN'S DISEASE ON THE PHARMACOKINETICS AND PHARMACODYNAMICS OF ALFENTANIL
Department of Anaesthesiology, University Hospital Leiden P.O. Box 9600, 2300 RC Leiden, The Netherlands
We have compared the dose requirements, pharma cokinetics and pharmacodynamics of alfentanil in 12 patients with Crohn's disease and 10 control patients undergoing abdominal surgery. Plasma concentrations of
1-acid glycoprotein (AAG) and alfentanil protein binding were also measured. Anaesthesia was induced with aifentanil 100 µg kg1 and thiopentone, and maintained with nitrous oxide in oxygen and aifentanil 25200 µg kg1 h1 Arterial blood samples were obtained before and after each change in the aifentanil infusion rate and for 6 h after stopping the infusion. Pharmacokinetic data were derived using non-compartmental methods. Alfentanil concen trationeffect data were evaluated by non-linear regression, where effect was either response or no response to surgical stimulation. Mean intra operative aifentanil requirement was greater in patients with Crohn's disease (2.48 µg kg1 min1) than in control patients (1.35 µg kg1 min1) (P< 0.01). Mean elimination half-life, total plasma clearance and steady state distribution volume in patients with Crohn's disease were comparable to those in control patients (80 vs 81 min, 5.7 vs 6.4 ml kg1 min1 and 0.70 vs 0.68 litre kg1, respectively). Mean plasma concentration at which the probability of no response was 50% for the intra-abdominal period of surgery was greater in the Crohn group (359 ng ml1) than in the control group (199 ng ml1 (P<0.02). Plasma AAG concentrations were greater in the Crohn group, but the free fraction of aifentanil was similar in both groups. This study indicates that the increased alfentanil requirement in patients with Crohn's disease may be attributed to a change in pharmacodynamics. (Br. J. Anaesth. 1993; 71: 827834)