What is the recommended use of Aminoven (amino acid solution) in preterm neonates?

Aminoven Use in Preterm Neonates

Start Aminoven (amino acid solution) at 1.5 g/kg/day on the first postnatal day, then increase to 2.5-3.5 g/kg/day from day 2 onwards with adequate non-protein energy (>65 kcal/kg/day) to achieve optimal growth and prevent protein catabolism. 1, 2

Dosing Algorithm by Postnatal Age

Day 1 of Life

• Initiate amino acids at minimum 1.5 g/kg/day as soon as possible after birth to prevent the metabolic shock from interruption of continuous intrauterine feeding 1, 2
• This early administration achieves positive nitrogen balance and increases protein synthesis without decreasing proteolysis 1
• Starting within the first 24 hours is associated with improved weight gain and fewer infants falling below the 10th percentile at 36 weeks post-conceptual age 3

Day 2 Onwards

• Advance to 2.5-3.5 g/kg/day of amino acids (strong recommendation, Level of Evidence 1+) 1, 2
• Must be accompanied by non-protein energy intake >65 kcal/kg/day 1, 2
• Ensure minimum 30-40 kcal per 1 gram of amino acids to guarantee proper utilization 1, 2

Maximum Dosing Limits

• Do not exceed 3.5 g/kg/day in routine clinical practice 1
• Doses above 3.5 g/kg/day should only be administered as part of clinical trials, as evidence shows no additional benefit and potential for amino acid imbalances 1, 2

Specific Amino Acid Requirements

Essential Supplementation

• Cysteine: 50-75 mg/kg/day (bioavailable form) - higher amounts do not improve outcomes 1, 2
• Tyrosine: minimum 18 mg/kg/day for preterm infants 1, 2
• Taurine: should be included in the amino acid solution, though specific limits are not firmly established 1, 2

Conditional Supplementation

• Arginine supplementation may be considered for prevention of necrotizing enterocolitis (NEC) in preterm infants (Level of Evidence 1, Grade B) 1, 2
• Glutamine should NOT be supplemented additionally in infants up to two years of age (strong recommendation, Level of Evidence 1++) 1, 2

Standard vs. Individualized Solutions

Use standard parenteral nutrition solutions for the majority of preterm infants, including very low birth weight (VLBW) infants (Level of Evidence 2, conditional recommendation) 1

When to Use Standard Solutions

• Stable preterm neonates without metabolic complications 1
• Standard solutions are nutritionally adequate, promote safer administration, and ensure consistent adherence to guidelines 1, 4
• Associated with cost savings without compromising growth outcomes 1

When to Use Individualized Solutions

• Switch to individualized formulations when:
  • Very sick and metabolically unstable patients 1
  • Abnormal fluid and electrolyte losses 1, 5
  • Short bowel syndrome or prolonged PN requirement 1, 5
  • Standard formulations cannot meet specific nutritional requirements 1

Critical Monitoring Parameters

Clinical Assessment

• Weight gain trajectory - target to prevent falling below 10th percentile at 36 weeks post-conceptual age 3
• Nitrogen balance - aim for positive balance with minimum 1.5 g/kg/day 1
• Glucose control - higher amino acid intakes may improve glucose stability 1

Laboratory Monitoring

• Plasma amino acid levels, particularly tyrosine and cystine 6, 7
• Electrolytes and mineral metabolism - high amino acid intakes can affect these parameters 1
• Liver function tests - monitor for cholestasis with prolonged PN 5
• Blood urea nitrogen - assess for excessive protein load 1

Common Pitfalls to Avoid

Timing Errors

• Never delay amino acid administration beyond the first day of life - this results in protein catabolism, negative nitrogen balance, and poor growth outcomes 1, 2, 3
• Delaying beyond 24 hours is associated with significantly worse weight gain 3

Dosing Errors

• Do not provide amino acids without adequate non-protein calories - minimum 30-40 kcal per gram of amino acids is required for proper utilization 1, 2
• Insufficient energy intake impairs amino acid incorporation into protein synthesis 1
• Avoid exceeding 3.5 g/kg/day - no evidence of benefit and increased risk of metabolic complications 1, 2

Composition Errors

• Do not use solutions lacking cysteine supplementation - preterm infants cannot synthesize adequate amounts 1, 6
• Ensure tyrosine content meets minimum 18 mg/kg/day - deficiency is common with standard solutions 1, 6, 7
• Never add glutamine supplementation in infants under 2 years - strong evidence against this practice 1, 2

Special Population Considerations

• In critically ill preterm infants, withholding PN for up to 1 week while providing micronutrients can be considered, though this remains controversial 1
• For infants with NEC, maintain bowel rest but ensure adequate amino acid intake (minimum 1.0 g/kg/day) once PN is resumed 8

Product-Specific Considerations for Aminoven

Aminoven contains N-acetyl-L-tyrosine and N-acetyl-L-cysteine, which improve stability and solubility compared to non-acetylated forms 6. However, approximately 38% of N-acetyl-L-tyrosine and 53% of N-acetyl-L-cysteine are excreted in urine unchanged 6. When using Aminoven specifically, monitor plasma levels of both acetylated and non-acetylated forms, as acetylated amino acids accumulate to higher plasma concentrations than their non-acetylated counterparts 6. The estimated cysteine intake should be 500 μmol/kg/day to achieve plasma levels comparable to normal term breast-fed neonates 6.