[Selenium supplementation in critically ill patients: pharmacological issues and current evidence].

High dose intravenous selenium may be associated with a significant reduction in mortality among critically ill patients with systemic inflammation. Currently, parenteral selenium as sodium selenite seems to be a cornerstone of the antioxidant defence in the critically ill. So far, several clinical trials have evaluated the effects of selenium in monotherapy or as part of a multi-micronutrient approach, on relevant clinical end points for critically ill patients. Nonetheless, the results from these studies have sometimes been contradictory. We now have a better understanding of the pharmacokinetics of the initial and transient pro-oxidant effect of an intravenous bolus followed by the antioxidant effect of continuous infusion, which seems efficacious and safe among critically ill patients. Clinical confirmation of the potentially advantageous synergism between selenium and glutamine may soon be forthcoming but the most appropriate and the optimum time of supplementation remains undetermined. Short-term intravenous selenite (bolus injection plus continuous infusion) has shown to be safe and capable of optimizing serum selenium and antioxidant selenoenzymes activities. However, additional dose-ranging trials are necessary to elucidate an optimal and safe posology with confirmed pharmacokinetic profiles before more definitive phase III trials can be conducted.