Elimination kinetics of L-alanyl-L-glutamine in ICU patients.

A randomised, double blind, placebo-controlled study was performed giving 0.5 g x kg(-1) x day(-1) of undiluted alanyl-glutamine (20%) or saline in a peripheral vein during 4 hours in ICU patients (n = 20). During the infusion period a steady state in plasma concentration was reached for alanyl-glutamine, but not for alanine, glutamine or glutamate. On the other hand there was no accumulation of any of the amino acids, as the pre-infusion concentrations were reached within 8 hours after the end of infusion. The half-life of the dipeptide was 0.26 hours (range, 0.15-0.63 h). The distribution volume of alanyl-glutamine was larger than the extracellular water volume, indicating a rapid hydrolysis of the dipeptide. There was no detectable alanyl-glutamine in the urine of any of the patients. All patients had excretion of small amounts of amino acids in urine, but the renal clearance of alanine, glutamine and glutamate were not different between the two groups.