DOSAGE AND ADMINISTRATION
The objective of nutritional management of patients with liver disease is the provision of sufficient amino acid and caloric support for protein synthesis without exacerbating hepatic encephalopathy.
The total daily dose of HepatAmine depends on daily protein requirements and on the patient's metabolic and clinical response. The determination of nitrogen balance and accurate daily body weights, corrected for fluid balance, are probably the best means of assessing individual protein requirements. Dosage should also be guided by the patient's fluid intake limits and glucose and nitrogen tolerances, as well as by metabolic and clinical response.
The recommended dosage is 80–120 grams of amino acids (12–18 grams of nitrogen) as HepatAmine® (8% Amino Acid Injection) per day. Typically, 500 mL of 8% HepatAmine appropriately mixed with 500 mL of 50% dextrose supplemented with electrolytes and vitamins is administered over an 8–12 hour period. This results in a total daily fluid intake of approximately 2–3 liters. Patients with fluid restrictions may only tolerate 1–2 liters. Although nitrogen requirements may be higher in severely hypercatabolic or depleted patients, provision of additional nitrogen may not be possible due to fluid intake limits, nitrogen, or glucose intolerance.
In many patients, provision of adequate calories in the form of hypertonic dextrose may require the administration of exogenous insulin to prevent hyperglycemia and glycosuria. To prevent rebound hypoglycemia, a solution containing 5% dextrose should be administered when hypertonic dextrose solutions are abruptly discontinued.
Fat emulsion coadministration should be considered when prolonged (more than 5 days) parenteral nutrition is required in order to prevent essential fatty acid deficiency (E.F.A.D.). Serum lipids should be monitored for evidence of E.F.A.D. in patients maintained on fat free TPN.
The provision of sufficient intracellular electrolytes, principally potassium, magnesium, and phosphate, is required for optimum utilization of amino acids. Approximately 60–180 mEq of potassium, 10–30 mEq of magnesium, and 10–40 mmole of phosphate per day appear necessary to achieve optimum metabolic response. In addition, sufficient quantities of the major extracellular electrolytes sodium, calcium, and chloride, must be given. In patients with hyperchloremic or other metabolic acidoses, sodium and potassium may be added as the acetate salts to provide bicarbonate precursor. The electrolyte content of HepatAmine must be considered when calculating daily electrolyte intake. Serum electrolytes, including magnesium and phosphorus, should be monitored frequently.
Use of HepatAmine in pediatric patients is governed by the same considerations that affect the use of any amino acid solution in pediatrics. The amount administered is dosed on the basis of grams of amino acids/kg of body weight/day. Two to three g/kg of body weight for infants with adequate calories are generally sufficient to satisfy protein needs and promote positive nitrogen balance. Solutions administered by peripheral vein should not exceed twice normal serum osmolarity (718 mOsmol/L).
Hypertonic mixtures of amino acids and dextrose may be safely administered by continuous infusion through a central venous catheter with the tip located in the superior vena cava. Initial infusion rates should be slow, and gradually increased to the recommended 60–125 mL/hr. If administration rate should fall behind schedule, no attempt to "catch up" to planned intake should be made. In addition to meeting protein needs, the rate of administration, particularly during the first few days of therapy, is governed by the patient's glucose tolerance. Daily intake of amino acids and dextrose should be increased gradually to the maximum required dose as indicated by frequent determinations of glucose levels in blood and urine.
For patients in whom the central venous route is not indicated and who can consume adequate calories enterally, 8% HepatAmine may be administered by peripheral vein with or without parenteral carbohydrate calories. Such infusates can be prepared by dilution of 8% HepatAmine with Sterile Water for Injection or 5%–10% dextrose to prepare isotonic or slightly hypertonic solutions for peripheral infusion. It is essential that peripheral infusion be accompanied by adequate caloric supplementation. In pediatric patients, the final solution should not exceed twice normal serum osmolarity (718 mOsmol/L).
Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit.
Care must be taken to avoid incompatible admixtures. Consult with pharmacist.