DISPOSITION OF INFUSIONS OF ATRACURIUM AND ITS METABOLITE, LAUDANOSINE, IN PATIENTS IN RENAL AND RESPIRATORY FAILURE IN AN ITU

A study of plasma atracurium and laudanosine concentrationswas undertaken in 14 critically ill patients who received abolus dose of atracurium 0.6 mg kg^–1 followed by an infusionof 0.6mg kg^–1 h^–1 for a period of 11–47 h.Seven of the patients had normal renal function and seven werein acute renal failure. In both groups plasma concentrationsof atracurium reached a plateau of approximately 1300 ng ml^–1within30 min of the bolus dose. The drug disappeared from the plasmawithin 120 min after discontinuation of the infusion. Therewas no difference between the two groups with respect to thepharmacokinetic parameters derived for atracurium. In the patientswith normal renal function, plasma laudanosine concentrationreached a plateau of apprpximately 1200ng ml^–1 within10h. In patients with renal failure there was a greater variationin the plasma laudanosine concentration: the highest value recordedwas 4300 ng ml^–1. Patients with renal failure had a significantlylonger mean elimination half-life for laudanosine (1418 minv. 375min; P < 0.05) and Vd (4.52 litre kg^–1 v. 240litre kg^–1; P < 0.01) than the patients with normalrenal function. ^*Present address: Southport General Hospital, Scarisbrick NewRoad, Southport, Merseyside PR8 6LF.