L-glutamine supplementation in home total parenteral nutrition patients: stability, safety, and effects on intestinal absorption.

A study was conducted to determine safety and efficacy of L-glutamine when added to total parenteral nutrition (TPN) solutions of patients receiving TPN in the home. Stability studies were first performed on various concentrations of L-glutamine in TPN solutions mixed by the Pharmix method. These showed that glutamine was stable in home TPN solutions for at least 22 days. The daily home TPN solutions of seven stable patients were then supplemented with glutamine at a dose of 0.285 g/kg of body weight for 4 weeks. The glutamine-TPN solutions were prepared weekly. Five patients received the full 4 weeks of glutamine-TPN. In two patients, administration of glutamine-TPN mixtures was stopped at the end of week 2 and week 3 because of elevations in liver enzymes. A third patient's liver enzymes rose at the end of week 4. These abnormalities subsided after discontinuation of the glutamine-TPN solution. Plasma levels of glutamine increased during the first 3 weeks of supplementation but these increases were not statistically significant. D-Xylose absorption studies performed before and after the administration of glutamine-TPN did not reveal any improvement in small-bowel absorptive capacity. In conclusion, stable glutamine-TPN solutions for use by home TPN patients can be formulated. However, supplementation of home TPN solutions at this dose was associated with apparent hepatic toxicity and did not demonstrate a beneficial effect on intestinal absorptive capacity as measured by D-xylose absorption. Therefore, on the basis of this study, routine supplementation of home TPN solution with glutamine cannot be recommended.