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The addition of heparin to the PN solution at a concentration of 0.5 to 1 units per mL (36) maintains the patency of the venous catheter, reduces vein irritation, and enhances lipid clearance by improving lipoprotein lipase enzyme activity. Heparin should not be used in patients with bleeding or at risk for bleeding, or in patients with thrombocytopenia.

Histamine-2 receptor antagonists such as ranitidine, famotidine, and cimetidine are compatible with PN and may be added to the PN solution for stress ulcer prophylaxis.

Regular insulin is compatible with the PN solution. However, insulin therapy is difficult to regulate in infants, and intravenous insulin should be administered as a separate intravenous infusion to allow safe titration of the insulin dose in this circumstance.

Iron deficiency anemia may occur in PN-dependent patients. Iron is not routinely added to PN. Iron dextran is the most common parenteral iron available for use when oral iron absorption is unreliable or results in gastrointestinal intolerance. Because iron can be used as a substrate for bacterial proliferation, iron dextran should be avoided in infected patients.

Because severe anaphylactic side effects may occur with iron dextran, an intravenous test dose should be administered before the total dose is given. Although not recommend by manufacturers, its use during the first 4 months of life has been safely demonstrated by many qualified groups. Daily iron dextran doses up to 1 mg per kg have been added to neonatal PN to prevent iron-deficiency anemia. Iron replacement calculations are found in Table 7-6. The estimated total iron dextran dose can be equally divided into incremental doses and added to the daily supply of nonlipid-containing PN solution until the total replacement dosage is given. Iron dextran at therapeutic doses is incompatible with lipid emulsions (37). Another, potentially safer intravenous iron preparation is sodium ferric gluconate (Ferrlecit, R&D Laboratories, Marina Del Rey, CA). The use of this has been predominately in renal failure patients, but it also appears effective in children (38).