Parenteral Nutrition Formulations, Compounding, and Administration
Components
PN includes dextrose, amino acids, lipids (separate or combined as 3-in-1), electrolytes, vitamins, trace elements, and sometimes insulin or heparin. Dextrose provides most non-protein calories; lipid emulsions provide essential fatty acids and calories. Standardized commercial products improve safety versus custom compounding.
Compounding and compatibility
Key stability issues: calcium-phosphate precipitation (risk rises with high calcium, phosphate, and low amino acid concentration, and with temperature), lipid emulsion stability (avoid excessive divalent cations, low pH, and high osmolality), and drug compatibility. Use standardized order sets, limit additives, and follow USP <797> for sterile compounding.
Administration
Central PN for high-osmolality formulas; peripheral PN limited to lower osmolality. Use infusion pumps, dedicated lines when possible, and taper when discontinuing long-term PN to avoid hypoglycemia. Lipid emulsions may be given separately or combined; monitor triglycerides.
Monitoring
Check glucose, electrolytes, renal function, liver enzymes, triglycerides, and fluid balance. Watch for catheter-related complications and metabolic derangements.
Worked rule of thumb
Before ordering a compounded PN with calcium and phosphate, verify amino acid concentration and total divalent content; if precipitation risk is high, use a standardized bag or separate administration.