ORNITHINE ALPHA-KETOGLUTARATE METABOLISM AFTER ENTERAL ADMINISTRATIONIN BURN PATIENTS - BOLUS COMPARED WITH CONTINUOUS-INFUSION

Ornithine alpha-ketoglutarate (OKG) has been successfully used as an e nteral supplement in the treatment of catabolic states, including burn injury. However, specific questions remain unanswered concerning burn patients, including OKG metabolism and metabolite production, appropr iate mode of administration, and dose. We thus performed akinetic stud y and followed plasma ornithine and OKG metabolite concentrations on d ay 7 postburn in 42 (35 men, 7 women) consecutive burn patients aged 3 3 +/- 2 y with a mean (+/- SEM) total burn surface area (TBSA) of 31 /- 1%. Patients were randomly assigned to receive OKG as a single bolu s (10 g, n = 13) or in the form of a continuous gastric infusion (10, 20, or 30 g/d over 21 h; n = 13) or an isonitrogenous control (n = 16) . Plasma pharmacokinetics of ornithine followed a one-compartment mode l with first-order input (r = 0.993, P < 0.005). OKG was extensively m etabolized in these patients (absorption constant = 0.028 min(-1), eli mination half-life = 89 min), with the production of glutamine, argini ne, and proline; proline was quantitatively the main metabolite [in OK G bolus, area under tile curve (AUC)(0-7h): proline, 41.4 +/- 5.6 mmol . min / L; glutamine, 20.4 +/- 5.7 mmol . min / L, and arginine, 7.3 +/- 1.9 mmol . min / L]. Proline production was dose dependent and qua ntitatively similar between modes of OKG administration. Glutamine and arginine production were not dose-dependent and were higher in the bo lus group than ill the infusion group. Overall, the bolus mode of OKG administration appeared to be associated with higher metabolite produc tion compared with continuous infusion in burn patients, especially fu r glutamine and arginine.